It was over 100 years ago that Einstein put forth, in its final form, the General theory of Relativity. The old Newtonian conception of gravitation where two massive objects attracted one another, instantaneously, with a force proportional to their masses and inversely proportional to the square of the distance between them disagreed with both the observations of Mercurys orbit and the theoretical requirements of special relativity: where nothing could travel faster than light, not even the force of gravity itself.

General Relativity replaced Newtonian gravity by instead treating spacetime as a four-dimensional fabric, where all the matter and energy traveled through that fabric: limited by the speed of light. That fabric wasnt simply flat, like a Cartesian grid, but rather had its curvature determined by the presence and motion of matter and energy: matter and energy tells spacetime how to curve, and that curved spacetime tells matter and energy how to move. And whenever an energy-containing object moved through curved space, one inevitable consequence is that it would emit energy in the form of gravitational radiation, i.e., gravitational waves. Theyre everywhere in the Universe, and now that weve begun to detect them, theyre about to open up the future of astronomy. Heres how.

Numerical simulations of the gravitational waves emitted by the inspiral and merger of two black holes. The colored contours around each black hole represent the amplitude of the gravitational radiation; the blue lines represent the orbits of the black holes and the green arrows represent their spins. The physics of binary black hole mergers is independent of absolute mass, but depends heavily on the relative masses and spins of the merging black holes.

The first two things you need to know, in order to understand gravitational wave astronomy, is how gravitational waves are generated and how they affect quantities that we can observe in the Universe. Gravitational waves are created whenever an energy-containing object passes through a region where the spacetime curvature changes. This applies to:

In all of these cases, the energy distribution within a particular region of space changes rapidly, and that results in the production of a form radiation inherent to space itself: gravitational waves.

These ripples in the fabric of spacetime travel at precisely the speed of light in a vacuum, and they cause space to alternately compress-and-rarify, in mutually perpendicular directions, as the peaks and troughs of the gravitational waves pass over them. This inherently quadrupolar radiation affects the properties of the space that they pass through, as well as all objects and entities within that space.

Gravitational waves propagate in one direction, alternately expanding and compressing space in mutually perpendicular directions, defined by the gravitational waves polarization. Gravitational waves themselves, in a quantum theory of gravity, should be made of individual quanta of the gravitational field: gravitons. While they might spread out evenly over space, the amplitude is the key quantity for detectors, not the energy.

If you want to detect a gravitational wave, you need some way to be sensitive to both the amplitude and frequency of the wave youre searching for, and you also need to have some way to detect that its affecting the region of space youre measuring. When gravitational waves pass through a region of space:

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Numerous detection schemes have been proposed, including vibrating bars that would be sensitive to the oscillatory motion of a passing gravitational wave, pulsar timing that would be sensitive to oscillatory changes of gravitational waves that passed through the pulses line-of-sight with respect to us, and reflected laser arms that span different directions, where the relative changes between the multiple path-lengths would reveal the evidence of a gravitational wave as it passed through.

When the two arms are of exactly equal length and there is no gravitational wave passing through, the signal is null and the interference pattern is constant. As the arm lengths change, the signal is real and oscillatory, and the interference pattern changes with time in a predictable fashion.

The last of these is precisely the first and thus far, the only method by which weve ever successfully detected gravitational waves. Our first such detection came on September 14, 2015 and represented the inspiral and merger of two black holes of 36 and 29 solar masses, respectively. As they merged together, they formed a final black hole of only 62 solar masses, with the missing three solar masses getting converted into pure energy, via E = mc, in the form of gravitational waves.

As those waves passed through planet Earth, they alternately compressed-and-rarified our planet by less than the width of a blade of grass: a minuscule amount. However, we had two gravitational wave detectors the LIGO Hanford and LIGO Livingston detectors that each consisted of two perpendicular laser arms, 4 km long, that reflected lasers back-and-forth over a thousand times before the beams were brought back together and recombined.

By observing the periodic shifts in the interference patterns created by the combined lasers, which themselves were caused by the passing gravitational waves through the space that the laser light was traveling through, scientists were able to reconstruct the amplitude and frequency of the gravitational wave that passed through. For the first time, wed captured these now-infamous ripples in spacetime.

GW150914 was the first ever direct detection and proof of the existence of gravitational waves. The waveform, detected by both LIGO observatories, Hanford and Livingston, matched the predictions of general relativity for a gravitational wave emanating from the inward spiral and merger of a pair of black holes of around 36 and 29 solar masses and the subsequent ringdown of the single resulting black hole.

Since that time, the twin LIGO detectors have been joined by two other ground-based laser interferometer gravitational wave detectors: the Virgo detector in Europe, and the KAGRA detector in Japan. By the end of 2022, all four detectors will combine to produce an unprecedented gravitational wave detector array, allowing them to be sensitive to lower-amplitude gravitational waves originating from across more locations on the sky than ever before. Later this decade, theyll be joined by a fifth detector, LIGO India, which will increase their sensitivity even further.

You have to realize that every gravitational wave that passes through Earth comes in with a specific orientation, and only the orientations that cause substantial shifts in both perpendicular laser-arms of an individual detector can lead to a detection. The twin LIGO Hanford and LIGO Livingston detectors are specifically oriented for redundancy: where the angles the detectors are at, relative to one another, is precisely compensated for by the curvature of the Earth. This choice ensures that a gravitational wave that appears in one detector will also appear in the other, but the cost is that a gravitational wave thats insensitive to one detector will also be insensitive to the other. In order to get better coverage, more detectors with a diversity of orientations including detectors sensitive to orientations that LIGO Hanford and LIGO Livingston will miss are necessary to win the Pokmon-esque game of catching them all.

The most up-to-date plot, as of November, 2021, of all the black holes and neutron stars observed both electromagnetically and through gravitational waves. While these include objects ranging from a little over 1 solar mass, for the lightest neutron stars, up to objects a little over 100 solar masses, for post-merger black holes, gravitational wave astronomy is presently only sensitive to a very narrow set of objects.

But even with up to five detectors, with four independent orientations between them, our gravitational wave capabilities will still be limited in two important ways: in terms of amplitude and frequency. Right now, we have somewhere in the ballpark of ~100 gravitational wave events, total, but all of them are from relatively low-mass, compact objects (black holes and neutron stars) that have been caught in the final stages of inspiraling and merging together. In addition, theyre all relatively nearby, with black hole mergers extended out a few billion light-years and neutron star mergers reaching perhaps a couple of million light-years. So far, were only sensitive to the black holes that are around 100 solar masses or under.

Again, the reason is simple: gravitational field strengths increase the closer you get to a massive object, but the closest you can get to a black hole is determined by the size of its event horizon, which is primarily determined by a black holes mass. The more massive the black hole, the larger its event horizon, and that means the greater the amount of time it takes for any object to complete an orbit while still remaining outside the event horizon. The lowest-mass black holes (and all of the neutron stars) allow for the shortest orbital periods around them, and even with thousands of reflections, a laser arm thats only 3-4 km long isnt sensitive to longer time periods.

Gravitational waves span a wide variety of wavelengths and frequencies, and requirea set of vastly different observatories to probe them. The Astro2020 decadal offers a plan to support science in every one of these regimes, furthering our knowledge of the Universe as never before. By the end of the 2030s, we can expect a fleet of various gravitational wave observatories that are sensitive to many different classes of gravitational waves.

Thats why, if we want to detect the gravitational waves emitted by any other sources, including:

we need a new, fundamentally different set of gravitational wave detectors. The ground-based detectors we have today, despite how fabulous they truly are in their realm of applicability, are limited in amplitude and frequency by two factors that cannot be easily improved. The first is the size of the laser arm: if we want to improve our sensitivity or the frequency range that we can cover, we need longer laser arms. With ~4 km arms, were already seeing just about the highest-mass black holes we can; if we want to probe either higher masses or the same masses at greater distances, wed need a new detector with longer laser arms. We might be able to build laser arms perhaps ~10 times as long as the current limits, but thats the best well ever be able to do, because the second limit is set by planet Earth itself: the fact that its curved along with the fact that tectonic plates exist. Inherently, we cant build laser arms beyond a certain length or a certain sensitivity here on Earth.

With three equally spaced detectors in space connected by laser arms, periodic changes in their separation distance can reveal the passing of gravitational waves of appropriate wavelengths. LISA will be humanitys first detector capable of detecting spacetime ripples from supermassive black holes and the objects that fall into them. If these objects are found to exist prior to the formation of the first stars, that would be a smoking gun for the existence of primordial black holes.

But thats okay, because theres another approach that we should begin taking in the 2030s: creating a laser-based interferometer in space. Instead of being limited by either the fundamental seismic noise that cannot be avoided as the Earths crust moves atop the mantle, or by our ability to construct a perfectly straight tube given the curvature of the Earth, we can create laser arms with baselines hundreds of thousands or even millions of kilometers long. This is the idea behind LISA: the Laser Interferometer Space Antenna, scheduled to be launched in the 2030s.

With LISA, we should be able to achieve pristine sensitivities at lower frequencies (i.e., for longer gravitational wave wavelengths) than ever before. We should be able to detected black holes in the thousands-to-millions of solar mass range, as well as highly mismatched black hole mass mergers. Additionally, we should be able to see sources that LIGO-like detectors will be sensitive to, except in much earlier stages, giving us months or even years of notice to prepare for a merger event. With enough such detectors, we should be able to pinpoint precisely where these merger events are going to occur, enabling us to point our other equipment particle detectors and electromagnetically-sensitive telescopes to the right location right at the critical moment. LISA, in many ways, will be the ultimate triumph for what we currently call multi-messenger astronomy: where we can observe light, gravitational waves, and/or particles originating from the same astrophysical event.

This illustration show how the Earth, itself embedded within spacetime, sees the arriving signals from various pulsars delayed and distorted by the background of cosmic gravitational waves that propagate all throughout the Universe. The combined effects of these waves alters the timing of each and every pulsar, and a long-timescale, sufficiently sensitive monitoring of these pulsars can reveal those gravitational signals.

But for even longer-wavelength events, generated by:

we need even longer baselines to probe. Fortunately, the Universe delivers us exactly such a way to do it, naturally, simply by observing whats out there: precise, accurate, natural clocks, in the form of millisecond pulsars. Found all throughout our galaxy, including thousands and tens-of-thousands of light-years away, these natural clocks emit precisely-timed pulses, hundreds of times per second, and are stable on the timescales of years or even decades.

By measuring the pulse periods of these pulsars precisely, and by stitching them together into a continuously-monitored network, the combined timing variations seen across pulsars can reveal these signals that no currently proposed human-created detector could uncover. We know there ought to be many supermassive black hole binaries out there, and the most massive such pairs could even be detected and pinpointed individually. We have lots of circumstantial evidence that an inflationary gravitational wave background should exist, and we can even predict what its gravitational wave spectrum should look like, but we do not know its amplitude. If were lucky in our Universe, in the sense that the amplitude of such a background is above the potentially detectable threshold, pulsar timing could be the Rosetta Stone that unlocks this cosmic code.

A mathematical simulation of the warped space-time near two merging black holes. The colored bands are gravitational-wave peaks and troughs, with the colors getting brighter as the wave amplitude increases. The strongest waves, carrying the greatest amount of energy, come just before and during the merger event itself. From inspiraling neutron stars to ultramassive black holes, the signals that we should expect the Universe to generate ought to span more than 9 orders of magnitude in frequency.

Although we firmly entered the era of gravitational wave astronomy back in 2015, this is a science thats still in its infancy: much like optical astronomy was back in the post-Galileo decades of the 1600s. We only have one type of tool for successfully detecting gravitational waves right now, can only detect them in a very narrow frequency range, and can only detect the closest ones that produce the largest-magnitude signals. As the science and technology underlying gravitational wave astronomy continues to progress, however, to:

were going to reveal more and more of the Universe as weve never seen it before. In combination with cosmic ray and neutrino detectors, and being joined by traditional astronomy from across the electromagnetic spectrum, its only a matter of time before we achieve our first trifecta: an astrophysical event where we observe light, gravitational waves, and particles all from the same event. It might be something unexpected, like a nearby supernova, that delivers it, but it might also come from a supermassive black hole merger from billions of light-years away. One thing thats certain, however, is that whatever the future of astronomy looks like, its definitely going to need to include a healthy and robust investment in the new, fertile field of gravitational wave astronomy!

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Why gravitational waves are the future of astronomy - Big Think

August is a big month if you enjoy stargazing or astronomy.

First things first - the final super moon of the year happens this month.

Unfortunately, that coincides with one of the bigger meteor showers of the year - the Perseids. The vibrant full moon will wash out all but the brightest meteors (still may be worth a shot to try and catch a few).

Pro tip: If you're interested in trying to catch some of the Perseids, try looking on a clear night away from the peak full moon.

Saturn reaches opposition around the middle of the month. This means that the Earth will be located between the Sun and Saturn. The ringed planet appears the biggest and brightest during this time of year.

The night of August 18, if weather permits, Saturn will be visible for most of the night. If you're interested in checking it out, grab your telescope to be able to see details of Saturn's rings and possibly some of the moons.

A little later in the month, the quarter Moon and Mars appear to 'meet' in the sky early on the morning of the 19.

For more on what you can see by looking up into the August night sky, click here.

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Celestial Events Happening This Month That You'll Want to Keep an Eye Out For - NBC Connecticut

One of my favorite galaxies in the sky is the Cartwheel, a very strange beast indeed located about 400 million light-years from Earth toward the constellation of Sculptor. Its about the same size as our Milky Way, over 100,00 light-years across. But its resemblance to our own home ends there

You may be familiar with spiral galaxies, ellipticals, and irregulars, but theres a small class called peculiar: Galaxies that have an overall shape, but that shape is strange. In this case, the Cartwheel is shaped like, well a cartwheel.

Its unusual for an astronomical object to have a nickname that really hits the mark, but in this case see for yourself:

That is a new JWST image of the Cartwheel, and holy wow is it spectacular! Its a combination of images taken by the Near-Infrared Camera, or NIRCam, and the Mid-infrared Instrument, or MIRI.

The bizarre structure of the Cartwheel is thought to be due to a collision it had with a smaller galaxy hundreds of millions of years ago. Small galaxies whack into bigger ones fairly often, but in this case it was a bullseye: The smaller one passed right through the center of a bigger spiral at high speed. The gravitational interactions under such circumstances are different than usual: The smaller galaxy created an expanding ring of gas and stars in the bigger galaxy very much like a rock dropped into a pond.

This splash expanded outward, creating the outer ring and riled up the inner hub of stars in the big spiral, creating the smaller inner ring. After the collision, the gas and stars in the disk of the bigger (now ex-) spiral still tried to rotate around the center, but the gravitational disturbance piled them up into thin lanes, creating the spokes you can see connecting the inner and outer rings. If youre curious, a few years back astronomers created a series of animations simulating the gravitational encounter between the two which you can find on their website. Our understanding of the collision has changed since then but these will give you an idea of what happened.

The NIRCAM images cover the wavelength range of about 0.9 microns a wavelength just longer than the human eye can see out to 4.44 microns, and are colored blue, green, yellow, and red. This shows older stars as well as the glow of dust from newborn stars, especially in the outer ring as the gas clouds there compressed and formed new stars by the millions.

MIRI sees farther into the infrared. In the first image thats shown in shades of orange, but here is a combination of MIRI images on its own:

Here blue is actually a wavelength of 7.7 microns, green 10 microns, yellow 12.8, and red 18 microns, well out into what we call the thermal infrared, where warm objects glow. You glow in IR, with a peak brightness at about 10 microns. Just sos you know.

Most luminous stars in visible light arent terribly bright at these wavelengths cooler red supergiants like Betelgeuse being an exception so stars dont show up well in MIRI images. Instead were seeing dust: tiny grains of silicates, or rocky material, and long chains of carbon molecules called polycyclic aromatic hydrocarbons, or PAHs. Think of them as soot, because thats basically what they are.

Dust is created in the atmospheres of dying stars and blown out into space in prodigious quantities; in 2020 when Betelgeuse dimmed so much it was because it blew a huge cloud of dust into space that partially blocked our view of it. Dust is opaque in visible light, the kind of light we see, but in thermal IR it glows. Thats what MIRI detects.

In the MIRI image you can see clumps of dust in the inner ring where bursts of star formation have created massive stars that burned through their fuel in only a few million years, turned into red supergiants, and blew out dust. Eventually those stars exploded as supernova, creating even more dust. These expanding clouds of dust collide and form long streamers, called dust lanes, in spiral galaxies, but in the Cartwheels outer ring it forms huge clumps. A recent supernova found just last year in the outer ring lends credence to this idea.

The spokes have a lot of dust too, created by stars that formed from gas compressed there as well, though its also possible the disk already present in the spiral galaxy before the collision had lots of dust, and those clouds were all gathered up in the gravitational wake of the intruder galaxy, creating the nearly radial features.

And speaking of the intruder galaxy, where is it? You might think its one of the two small galaxies on the left, but theyre actually just innocent nearby galaxies; they are at roughly the same distance from us as the Cartwheel so they may all be part of a small group. The intruder is actually a third nearby galaxy not seen in this relatively small section of sky observed by JWST. It can be seen in wider images, and in fact radio observations showing neutral hydrogen gas show the two are connected, a tail of gaseous debris left in the aftermath of the collision.

You can see why the Cartwheel is among my favorites. These images will help astronomers unravel what actually happened there. We already understand a lot about how collisions work, but each one is different. The more we observe the better well grok them, and JWST will be able to probe what occurs before, during, and after these immense cosmic train wrecks.

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Bad Astronomy | JWST observes the bizarre Cartwheel Galaxy | SYFY WIRE - Syfy

Imagine a childhood filled with telescopes, night skies and an ongoing fascination with the stars, planets, and galaxies. Robert Quimby lived it.

Its really all my parents fault. They were both amateur astronomers, so some of my earliest memories growing up are of looking through a telescope, says the professor of astronomy at San Diego State University and director of the Mount Laguna Observatory. We went on lots of star parties, which are basically camping trips with telescopes. I was independently driven, so I learned to star hop around and locate deep sky objects, like galaxies, myself.

On Friday, hell present a lecture highlighting some of the research being done at the observatory, along with some of the nonprofit work being done to reduce local light pollution. His presentation begins at 2 p.m. at the Alpine Library.

Quimby, 45, lives in the College Area with his wife, Mika, and their two girls. Hes received awards for his research and work from the Astronomical Society of the Pacific, the American Physical Society, and a share of the 2014 Breakthrough Prize in fundamental physics. He took some time to talk about his work, his first impressions of the breathtaking images from NASAs James Webb Space Telescope, and the time he played in a Reel Big Southern California ska band.

Q: In the description for your talk, the San Diego County Librarys website mentions the Hidden Skies Foundation, a nonprofit run by high school students based in Los Angeles, and its work to preserve dark skies for future generations. First, can you talk about light pollution?

A: Any human-made light that shines where it is not needed, is not helpful, or is just generally a waste, is light pollution. This could be a streetlight shining through a bedroom window that gives you a rough night of sleep, although astronomers usually use the term when discussing the light that spills onto the night sky and obscures the stars. No one sets out to hide the stars behind the glare of electric lights, but just as trash collects in our rivers and beaches, the natural beauty of the night sky can be destroyed by light indiscriminately cast by outdoor lighting.

Q: And what is significant about the work to preserve the darkness of night skies? Why does that lack of light in the sky matter?

A: Dark, star-filled skies give us connection to our past and hopefully our future. From a dark site, you might see the same stars that your great-great-great grandparents enjoyed on their first date, or that dazzled our ancient ancestors thousands of years before. Light pollution breaks this connection by hiding the stars. I have seen the thrill of San Diegans glimpsing their first view of the Milky Way while camping in Mount Laguna, and I would say it is worth protecting these views for future generations to enjoy as well.

We have great neighbors where we live in College Area. Several families welcomed us to the neighborhood soon after we moved here, and our kids became fast friends. There are lots of friendly waves when people walk or drive by. And, there are four taco shops within walking distance!

Q: Youve been director of SDSUs Mount Laguna Observatory since 2014. What have you come to learn about the surrounding area over the years and its place in the study of astronomy?

A: The Mount Laguna Observatory sits at 6,100 feet (500 feet higher than our colleagues to the north at Palomar Observatory, but whos counting!), so when the marine layer of clouds sets in in typical May-gray/June-gloom fashion, we are usually in the clear above the clouds. Better yet, the low clouds block some of the light pollution from the cities and make the nights even darker. Being near the coast we also get the gentle ocean breeze, which affords us much sharper views of the stars than the turbulent air further inland.

Q: What drew you to become interested in this area of study?

A: [Astronomy] remained a hobby of mine into college when it came time to decide on a major. I started with engineering since I liked figuring out how things worked, but I gravitated to physics and astronomy, at least in part because I thought the professors were more interesting people. One once plopped down a bunch of rock-climbing gear at the beginning of a lecture then proceeded to talk the whole period without ever mentioning it. He was just doing some rock climbing before class. These extra dimensions of personality really appealed to me.

Q: Why was this something you wanted to pursue professionally?

A: I figured its better than getting a real job. I love solving puzzles, but sometimes, when the puzzle is something you have to do, it can feel a lot like work. As an astronomer, there is a whole universe of puzzles for me to choose from.

Q: Earlier this month, most of us were in awe of the images of galaxies NASA shared from its James Webb Space Telescope. What initially went through your mind as you looked through those images?

A: I was really surprised at how awestruck I was. I have seen Stephans Quintet and the Carina Nebula before, but the James Webb telescope pictures convey them with such power and beauty. They are at once familiar and otherworldly.

Q: And how did you think about what you saw from your perspective as an astronomy professor and researcher?

A: The first images show how much we have been missing. The James Webb telescope offers, quite literally, a new way to look at our universe, and we are starting to see things we have never seen before. It was quite terrifying at times to wonder what would happen to the future of astronomy if this telescope failed; now that it has arrived and is working superbly, I, for one, am elated.

Q: Whats been challenging about your work in this field?

A: Like the universe itself, the field of astronomy is big and growing at an accelerated pace. It takes effort to stay on top of all of the new discoveries rolling in. It is also very competitive at times. Other groups are often working on projects similar to mine, so there is pressure to publish first.

Q: Whats been rewarding about this work?

A: Every once in a while, you make a breakthrough discovery. I discovered a new class of supernovae and later discovered the first supernova magnified by a strong gravitational lens. It is quite a rush when you put the pieces together and realize you have something that no one has ever seen before.

Q: What has this work taught you about yourself?

A: A big part of science is telling the story. We report our findings in scientific journals and give professional and sometimes public talks. I never considered myself particularly good at writing as a student, but I have come to realize that the storytelling is something I enjoy.

Q: What is the best advice youve ever received?

A: For anyone considering getting their Ph.D., take a year off between undergraduate and graduate school and do something totally different. One of my college professors gave me this advice, and it gave me the opportunity to broaden my world view and, ultimately, meet my wife. If, like me, you find academia calling you back, then you will know that graduate school is right for you, and you will be motivated to stick with it even when it gets tough (it will).

Q: What is one thing people would be surprised to find out about you?

A: Before becoming an astronomer, I played trombone in the ska band Reel Big Fish. It has been a while since I last picked up my horn, but I can still say, pick it up pretty fast.

Q: Describe your ideal San Diego weekend.

A: I have never done it before, but I would love to take a staycation at one of the local resorts in San Diego. Ideally, one with entertainment for the kids and relaxation for the parents. Barring that, I would enjoy a weekend featuring a hike in Mission Trails with my family and a trip to a new restaurant one day, followed by a relaxing day at the beach and a barbecue with friends and family the next day.

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Award-winning researcher and prof has stars in his eyes, will give astronomy talk in Alpine - The San Diego Union-Tribune

Astronomers have many tools for studying the cosmos: telescopes, satellites, interplanetary spacecraft, and more. The humble human eye is a critical part of this toolkit, too, as it can often spot patterns or aberrations that algorithms miss. And our visions scrutinizing power has been bolstered recently by virtual reality (VR) as well as by thousands of eyes working in tandem thanks to the crowdsourcing power of the Internet.

Researchers at NASAs Goddard Space Flight Center recently announced the discovery of 10 stars surrounded by dusty debris diskswhirling masses of gas, dust and rock left over after the earliest phases of planet formation. This result, enabled by VR and the help of citizen scientists, was recently published in the Astrophysical Journal. The findings could help astronomers piece together a time line of how planetary systems are built.

Debris disks encompass various stages of planet formation, including the youthful eras in which worlds are still embedded in the detritus from the messy, chaotic processes of their birth. Although astronomers have managed to see a few directly, most of these young planets are beyond the reach of current telescopes. Making a planetary system takes millions of years, so each debris disk observers see is just a brief snapshot of one moment in that systems life. To uncover the whole story, astronomers search for many disk-wreathed planetary systems at different stages of evolution, gathering multiple snapshots to piece together in a time line.

To hunt for debris disks, observers usually start by looking for stars that appear especially bright in the infrared; that abnormal brightness typically comes from a surfeit of starlight-warmed dust in a disk around a star. NASAs infrared telescope WISE (Wide-Field Infrared Survey Explorer) surveyed the entire sky, creating what in some respects is the most comprehensive catalog yet of stellar infrared measurements. With tens of thousands of data points to be analyzed and many debris disks likely hidden within the WISE catalog, whats a scientist to do?

Its a great example of how so much of modern astronomy involves searching massive data sets for the proverbial needle in the haystack, says Meredith Hughes, an astronomer at Wesleyan University, who was not involved in the study. Even with machine-learning algorithms, its still hard to train computers to do this complex work of identifying noisy patterns and noticing subtle deviations from expectations, which is where the collective brainpower of citizen science comes in.

A project called Disk Detective trained citizen scientistsregular people who want to help out on research in their spare timeto look at WISE images and compare them to those from other astronomical surveys, such as the SkyMapper Southern Sky Survey, the Pan-STARRS survey and the Two Micron All Sky Survey (2MASS), with the goal of confirming the presence of disks around each candidate star. Since the projects start in 2014, citizen scientists have found more than 40,000 disksthats 40,000 snapshots of the history of how planets form.

To put these into a time line, though, astronomers need to figure out where each snapshot belongs. In other words, scientists need to know the ages of each star and its debris disk. When we know the ages of stars and planets, we can place them in a sequencefrom baby to teen to adult, if you like, says Marc Kuchner, a NASA astrophysicist and co-author of the new study. That allows us to understand how they form and evolve.

Pinning down a stars age with any substantial precision is a notoriously tricky problem in astronomy. One solution is to match up a star to its siblings, in an association known as a moving group. Stars often form in clusters from one giant cloud of gas, but many of these once-close stellar families drift apart as they age, their individual members spreading out across the Milky Way. By carefully measuring stars locations and velocities, researchers can determine which stars display the telltale motions that, traced backward, reveal they were collectively born at the same time and place. Once astronomers know stars in a group are related, its straightforward to calculate their age based on established knowledge of how stars grow and evolve.

Finding new moving group members isnt easy. To do so, astronomers traditionally rely on analyzing preexisting lists of moving-group stars, flagging potential new members via sophisticated mathematical models. The team behind the new project wanted to try something different and more visceral: it used a VR program to zoom around the stars and get a clearer, three-dimensional perspective on how things move.

I thought I would scare [NASAs VR scientists] away when I said I wanted to visualize the positions and velocities of four million stars, Kuchner says. But they didnt bat an eyelash! To create this virtual stellar cornucopia, the team used data from Gaia, a European Space Agency satellite that provides the best available measurements for the positions and velocities of stars in our galaxy. The resulting VR simulation served as a sort of time machine, tooknowing how fast and in what direction a star was moving allowed Kuchner and colleagues to trace its movement backward and forward in time.

While serving as a visiting researcher at NASA, lead study author Susan Higashio strapped on a VR headset to fly around the simulations millions of stars. She examined where the stars with disks were in relation to known moving groups and extrapolated the stars motions forward and backward in time to test their potential associations. It was so exciting when the four million stars appeared in VR, but it felt a little dizzying when they all started to swirl around me, she recalls. It was a really fun and interactive way to conduct science.

Higashio traced 10 of the debris disks from Disk Detective back to their moving-group families. The team then found the estimated ages of these disks, which ranged from 18 million to 133 million years old. All of them were extremely young, compared with our home solar system, which is around 4.5 billion years old. The researchers also identified an entirely new moving group called Smethells 165, after its brightest star. Whenever we find a new moving group, thats a new batch of stars whose ages we know more precisely, Kuchner explains.

The astronomers also found one strange, extreme debris disk around a star nicknamed J0925 that doesnt quite fit into their expected time line of planet formation. Its much brighter in the infraredmeaning it has more dustthan expected for a star of its age. As debris disks get older, some of their dust spirals into the star or is blown away by stellar winds. J0925, however, seems to have just gotten a fresh new delivery of hot dust, possibly from a recent collision between two protoplanets. Hughes highlights this star as the most interesting object uncovered in the study. Extreme debris disks are still a bit mysterious, but they are probably similar to what our solar system would have looked like during the giant impact that formed the Earths moon.

Disk Detectives citizen-science work is still ongoing, now upgraded to use Gaias most recent batch of data. The team hopes to identify even more members of moving groups and new disks with their unique VR method. Lisa Stiller, one of the many citizen scientist co-authors of the study, offers encouragement for prospective volunteers. Dont hesitate to help out in a citizen-science project, she says. Your help will be needed in whatever form you choose or amount of time you choose to dedicate yourself.

Anyone with an Internet connection can still join the Disk Detective project, no experience needed. More than 30,000 citizen scientists have contributed, Kuchner says. The Disk Detectives are still working their way through hundreds of thousands of WISE imageswe still need your help.

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Planetary Debris Disks Discovered with Citizen Scientists and Virtual Reality - Scientific American

Myriam Alqassabs unique initiative got her discovering the world above

By Anu Prabhakar

Published: Thu 4 Aug 2022, 7:58 PM

On December 26, 2019, an annular solar eclipse was expected to occur and Myriam Alqassab decided to organise a public event to invite people to watch it. The eclipse started at 6:15am and ended at 8am, but our activity began at 4am. I thought no one would come I didnt think people would wake up early in the morning only to observe the sun, recalls the founder of the Bahrain Stargazers Astronomy Club. Myriam arranged 20 solar glasses and about five telescopes with solar filters for what she assumed would be a small, low-key event attended by citys astronomers and members of her club. We waited on Nurana Islands with our gear and cars began to arrive. Around 100 people ended up at the event, and I had no solar glasses to give them, she says. Her excitement is palpable as she recalls how shed asked them to hurry up so that everyone could share the glasses and watch the eclipse. Thank God there was no Covid then.

As she watched the place fill up with families one senior citizen climbed up a slope to watch the eclipse through the telescope Myriam felt hopeful. It also confirmed something that she had long suspected that the city was home to a sizeable population of astronomy enthusiasts, but that they had no opportunities to indulge their interest in astronomy.

In an interview via Google Meet, Myriam talks about forming the club in Bahrain, making the stars more reachable through on-ground stargazing activities, and her recent efforts to reduce light pollution.

Discovering astronomy

When Myriam felt a little lost in life at 16, she found Galileo. She chanced upon a documentary on the Italian astronomer, on YouTube. Back then, we had very little access to the Internet you had these cards, which you inserted into your computers for 20-30 minutes of access, she says. Id bought my first card and was using my friends computer at the time. By the end of the documentary, Myriam felt there was a cosmic connection between the two. His story touched my heart and I started to read more about stars, planets and astronomy.

She worked in the hospitality industry for a few years, although her heart was not in it. It was just a job to earn money to live, she says. Then I got pregnant and stopped working to look after my child. But I realised I didnt like being at home, doing nothing. Thats not me.

Meanwhile, she noticed other countries and regions robust participation in international astronomy events. But I didnt see the Middle East anywhere, she says. I wanted to get involved and wanted local stargazers to participate not only in local activities, but in international activities as well. So in 2016, she founded the Bahrain Stargazers Astronomy Club. It was an opportunity to meet other astronomy enthusiasts in the city so that we could learn from each other.

The early days were hard, but her organisational skills, thanks to her experience in the hospitality industry, helped. I did not know where to start or what to expect. I shared a link to register via WhatsApp and we received around 300 applications. I accepted all of them and then created a WhatsApp group for the members. Gradually, those who were only curious about the club went away and today, we have around 90 active members, she says.

As the founder of an astronomy club, she wanted to polish up her knowledge on the subject so she enrolled for an astronomy course that was being taught via distance education at Liverpool John Moores University. I am currently pursuing higher studies in astronomy at the University of Central Lancashire, she adds.

Teaching the young

Since 2019, she has organised around 10 webinars for schools, with space and astronomy experts as speakers. Our international speakers are from the US, Europe and India, she says. She has also been organising regular stargazing activities for club members at Nurana Island.

And then, there are the bigger events, like eclipses, comets and other such celestial spectacles for which she tries to organise public events. For instance, this year, when Mercury, Venus, Mars, Jupiter and Saturn aligned in the sky reportedly for the first time since 2004, Myriam spread the news through their social media accounts. People were welcome to join and use our equipment to observe the skies, she says.

They also organise workshops in collaboration with organisations like Hope Institute For Special Education and Al Kawther Society for Social Care Orphan Care. We taught the children how to use the telescope, about the solar system and Mother Earth. We want everyone to know about astronomy and have the opportunity to gaze through a telescope.

All this is funded by Myriam and the clubs devoted members a few of them also double up as volunteers. They arrange equipment like telescopes, and some members pay for papers, pens, water and utensils for our events.

Tackling light pollution

More recently, Myriam is focused on reducing light pollution in Bahrain by spreading information about it among the clubs members and then encouraging them to spread it among their friends, like gossip. When we go out to stargaze, our skies are not dark, they are orange. You cannot enjoy the stars, planets, she points out. I try my best to educate our society about how even the lights in their houses contribute to light pollution. In fact, Myriam plans to launch a free consultation service for those who would like to change their houses lights and design. I can show them the type of lights they can use, where and how to use them anything less than 1,000 kelvins is good for indoor lights and for outdoor lights, anything less than 3,000 kelvins is fine. Also, your lights should be covered by a shield, she says, adding that they had collaborated with IKEA to educate members and the public on how to choose lights.

Myriam is an International Dark Sky Association (IDA) delegate and advocate the association, which has local chapters, encourages delegates, advocates and volunteers to work with policymakers to reduce light pollution in public places. But its hard to change the system in the Middle East, which is why I am educating students right from kindergarten, because they can change the future, she says. She talks about light pollution in her webinars and also translated the IDAs brochure into Arabic and added it to the clubs social media accounts and websites. We also organise on-ground activities and teach participants to use the Globe at Night programme, where people look for stars and submit their observations through the app, she says. Globe at Night, then, puts these observations together and presents data about light pollution across the world, in the form of a map.

She is also the National Outreach Coordinator for the International Astronomical Union (IAU). My job is to provide the IAUs activities in my country and help our members participate in them, she elaborates. One of her standout memories is from the year 2020, when Myriam and the members enrolled in the International Asteroid Search Collaboration to discover asteroids in the asteroid belt. You have to stack four pictures together and put them in the software called Astrometrica to detect movement. She still remembers the surge of joy they felt when they noticed an asteroid moving. We jumped for joy and were over the moon, she smiles.

wknd@khaleejtimes.com

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How a Bahrain-resident is spreading awareness on light pollution through her astronomy club - wknd.

When you think of a galaxy, you probably picture some gorgeous, sprawling spiral-armed disk loaded with bright blue stars and pink/red clouds of gas dotted along the arms. And in truth many galaxies are like that, including our Milky Way, while others are elliptical, or irregular, or even peculiar.

The common denominator is that theyre loaded with stars, millions or billions of them, so many that from a distance they blur together into a milky glow.

But recently astronomers found some galaxies that dont look like this at all. Located billions of light-years from Earth, they seem to defy what we know about galaxy structure. Almost no starlight is seen from them, and most of the light they emit is in very long wavelengths, far outside what the human eye can see. Theyre dusty that is, they have clouds made up ofgrains of iron, rocky, or sooty (carbonaceous) material but that dust is a lot colder than youd expect for a normal galaxy.

These weird galaxies have been a mystery for a while, but now a team of astronomers thinks they have the answer: These galaxies arent just dusty, theyre choked with dust, so much that they completely block the starlight coming from inside them. In fact, these galaxies are positively bursting with star formation, but its buried so deeply in opaque dust that these galaxies are dark in the kind of light we see. If they didnt have all that dust these galaxies would be blazingly luminous [link to paper].

The galaxies were found in deep survey observations of the sky. Theyre practically invisible even when observed in the near-infrared, just outside the visible spectrum, but at progressively longer wavelengths, from mid-infrared out to radio waves, they get brighter. If these were normal galaxies with a normal amount of stars making light and warming up the dust around them, theyd be brighter at shorter wavelengths of infrared. But theyre not.

Four such galaxies were known previously. The astronomers observed six more, all very far away; their light took roughly 12 billion years to reach Earth. Typically, to measure the galaxies properties, astronomers make some basic assumptions. For example, they assume the dust in star-forming clouds is thick enough to block visible light, but lets infrared light through. Thats usually a decent assumption.

But when they did that for these 10 galaxies they get contradictions and physical properties that dont make sense. Thats usually a good sign one or more assumptions youve made is wrong. So they then changed that assumption, and redid the math assuming the dust is very, very thick; so dense that not even infrared light can get out.

And suddenly the physics started making sense.

These galaxies are absolutely jam-packed with dust, so much so that even in infrared were only seeing the surface of these clouds. Its not so much these galaxies have more dust than usual, but that theyre small, so the density of dust is far higher. Normally infrared light can escape even from deep within a dust cloud, but in this case theyre so dense theyre opaque to it.

And that in turn means that to explain the amount of light we do see, these galaxies are cranking out stars, dozens of times the rate at which the Milky Way makes them. These are true starburst galaxies, even though, bizarrely, they emit no optical light we can see. Theyre dark galaxies.

OK, so thats just objectively cool; galaxies so thick with dust they veil what theyre doing inside. But this is actually important to understand. We measure the star formation rates of galaxies in various ways, but its a great way to understand what a galaxy is doing, how much gas and dust it has, and so on. The rate at which stars are born tells us a lot about the galaxy and also what the Universe itself was doing when the light we see left that galaxy, so sometimes deep in the past.

The fact that there are galaxies prodigiously churning out stars yet have been completely overlooked because theyre dark means weve missed a big piece of the early Universe; the astronomers estimate as many as 10% of all dusty galaxies in the early Universe are so dusty theyre dark.

The next question to answer is why theyre this way. Are these examples of galaxy collisions in the early Universe? Are the stars forming there under different conditions than in the nearby Universe, such that they make more dust? With only 10 sample galaxies known this isnt clear.

What is clear is that were still learning about what the distant, early cosmos was like, and that sometimes what we want to see is hidden from us until we find a clever way to see it. In this case a big chunk of star-forming galaxies were invisible. What else is out there weve overlooked?

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In the early Universe, dark galaxies swarmed - Syfy

A newly released image of 30 Doradus, also known as the Tarantula Nebula, reveals thin spider-web-like strands of gas revealing a dramatic battle between gravity and stellar energy that could give astronomers an idea of how massive stars have shaped this star-forming region and why they continue to be birthed within this molecular cloud.

The high-resolution image of the Tarantula Nebula, located 170,000 light-years from Earth is made up of data collected by Atacama Large Millimeter/submillimeter Array (ALMA). Located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, the Tarantula Nebula is one of the most luminous star-forming regions in our galactic backyard. It is also one of the most active in terms of birthing new stars, some of which have masses more than 150 times that of the sun. At theits heart of the Large Magellanic Cloud lies a stellar nursery that has given rise to 800,000 stars, half a million of which are hot, young, and massive stars.

This makes the nebula a prime target for researchers who want to study star formation, and it has another unique property that makes it an exciting prospect for research study.

"What makes 30 Doradus unique is that it is close enough for us to study in detail how stars are forming, and yet its properties are similar to those found in very distant galaxies when the Universe was young," European Space Agency (ESA) scientist Guido De Marchi, a European Space Agency scientist and co-author of a paper describing the work, said in the statement. "Thanks to 30 Doradus, we can study how stars used to form 10 billion years ago, when most stars were born."

The "push and pull" researchers observed is created by the energy provided by its huge population of stars and gravity, with the former ripping gas clouds into strand-like fragments thus slowing star formation, and the latter attempting to bring gas clouds together to form stars.

These fragments may be the remains of once-larger clouds that have been shredded by the enormous energy being released by young and massive stars, a process dubbed feedback, Tony Wong, a professor from the Astronomy Department at the University of Illinois at Urbana-Champaign said in a European Southern Observatory (ESO) press release (opens in new tab).

The findings also showed that despite intense stellar feedback, gravity is still shaping the nebulawhich is located 170,000 light-years away from Earth and next to the Milky Wayand driving the continued formation of massive stars.

This contradicts the previous consensus on such star-forming regions which has suggested that thin strands of gas as seen in the Tarantula Nebula should be too disrupted by this feedback to allow gravity to pull it together and form new stars.

"Our results imply that even in the presence of very strong feedback, gravity can exert a strong influence and lead to a continuation of star formation," Wong continued.

Given its properties, it's unsurprising that the Tarantula Nebula has been well-studied. What makes this new research different is while previous studies have mostly focused on its center the site of the densest gas and thus the most rapid star formationastronomers are aware that stars are also being formed in other regions of the nebula this team collected high-resolution observations of a large region of the Tarantula Nebula rather than focusing on its heart. With this global approach to the nebula in mind they then dived it into clumps which revealed a surprising pattern.

"We used to think of interstellar gas clouds as puffy or roundish structures, but its increasingly clear that they are string-like or filamentary," Wong said in a National Radio Astronomy Observatory (NRAO) press release (opens in new tab). "When we divided the cloud into clumps to measure differences in density we observed that the densest clumps are not randomly placed but are highly organized onto these filaments."

Focusing on the light emitted by carbon monoxide gas allowed the researchers to map the large, cold gas clouds in the Tarantula Nebula that collapse to form infant stars. They also observed how these gas clouds change as those young stars release a tremendous amount of energy.

"We were expecting to find that parts of the cloud closest to the young massive stars would show the clearest signs of gravity being overwhelmed by feedback," Wong said. (opens in new tab) "We found instead that gravity is still important in these feedback-exposed regionsat least for parts of the cloud that are sufficiently dense."

Overlaying the data collected by ALMA and an infrared image of the Tarantula Nebula showing bright stars and glowing hot gas from the Very Large Telescope and from the Infrared Survey Telescope for Astronomy (VIS (opens in new tab)TA) creates a composite image that shows the extent of its gas clouds and their distinct web-like shape.

While the teams findings give an indication of how gravity affects star-forming regions, the research is a work in progress. "There is still much more to do with this fantastic data set, and we are releasing it publicly to encourage other researchers to conduct new investigations," Wong concluded.

Future studies will also focus on the differences between the Milky Way and the Tarantula Nebula including star-formation rateswhile our galaxy steadily forms stars, the Tarantula Nebula does so in boom and bust cycles.

The research on the Tarantula Nebula was presented at the 240th meeting of the American Astronomical Society (AAS) in Pasadena, California, on June 15. The findings are also presented in a paper in The Astrophysical Journal.

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Astronomers image the star-birthing web of a cosmic Tarantula Nebula - Space.com

A young astronomy-mad teenager who was visiting his grandparents fell off their balcony to his death while he was trying to see the stars.

Marcel Bruchal, 14, from Newham, East London, fell at 9.15pm on March 19, 2022, from his grandparents newly-refurbished maisonette at Sleaford House in Bow.

An ambulance was called at 9.13pm and arrived at the scene for 9.35pm finding Marcel in cardiac arrest, MyLondon reported.

READ MORE:Drivers risk 1,000 fines for cleaning car during UK hosepipe ban

Paramedics performed CPR and provided him with breathing equipment, however, efforts to resuscitate him were stopped at 10.09pm, shortly after arriving at Royal London Hospital.

Marcel attended the Oasis Academy Silvertown, in North Woolwich, where he was well-liked.

A heartbreaking statement from his grandmother, Iwona Wozniak, in the coroners report said that after a nice day eating together and playing ping pong, the family had "danced around".

"While we were dancing salsa Marcel left to go to the toilet for a while. [A family member] followed him out as he did not think he was coming back," she said.

He saw Marcel standing by the balcony and looking down. He described Marcel looking at it in a weird way."

She and Marcel then went to Tesco where Marcel was "joined at my hip", which she thought was weird at the time".

When they got back Marcel watched Jumanji and he then suggested karaoke after dinner.

"[He] went out and [another family member] said he was looking out in a weird way. I asked and he said he was looking down.

She continued: "I heard them shout 'Marcel no Marcel no Marcel why?' [He was] next to me shouting and crying but I could not make sense of what he was saying.

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They grabbed my hand and took me to the balcony... I saw two people and a car.

Then I saw someone laying there. My sight is not good but then I recognised Marcel's top. I was shouting 'Chris, Chris' and then 'Jesus Christ'.

"When I came out of the hallway Chris was already halfway down the stairs. I told him and he said 'what are you saying'. We went down in the lift.

We ran out of the block and we saw him laying there. He was not on the pavement, he was laying far from the building. He was bleeding from his mouth.

"My husband moved him around a bit. I was shouting hysterically, I was shaking. I told my husband not to touch him.

I could see he was dead, his legs were bent and he was not moving. He shouted for me to go get a towel and prop up his head.

I wanted to cover him up with the patchwork but at that point the ambulance turned up."

Coroner Mary Hassell said: "Some elements of how Marcel died are clear to me, but some are more difficult to understand. No other person was involved with that.

"Marcel must have climbed up onto the balcony in order to leave it. This was a safe balcony, he was a 14-year-old. This was not simply that the balcony was unsafe.

"All the evidence I have heard is that he was a very happy child. He was much loved, doing well at school.

Concluding, she said: "The likelihood is that he fell from the balcony and that this was an accident fall."

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Astronomy lover, 14, plummeted from grandparents' balcony trying 'to watch the stars' - Daily Star

Astronomers have witnessed a rare and important life event in the evolution of binary star couplings for the first time.

The team discovered a tight binary star surrounded by an expanding shell of material. This shell is matter is leftover from a stage in the stars' evolution called the common envelope phase.

This phase occurs when material from one star swells out and engulfs the other in a cosmic 'embrace.' This results in a mass transfer from the swelled star to its companion that can run out of control. The aftermath of this phase is something astronomers had not glimpsed until now.

Related: NASA's SOFIA flying telescope spots eclipse of odd binary star

"The common envelope phase is a missing link in the very long and complex chain of events making up the life of stars," Australian National University (ANU) associate professor Christian Wolf and part of the team that made the observations, said in a statement. (opens in new tab) "Now we are starting to fix that link."

Half of all stars in the universe come in binary pairs and though the initial stages of partnerships can be uneventful, when one star runs out of hydrogen for nuclear fusion things get interesting for the pairing.

The initial step in these events is the collapse of the hydrogen-exhausted core of the star while its outer layers 'puff out' a process that the sun will experience in around 5 billion years creating a red giant star. But, this proceeds differently for stars in binary pairs than it will for our lonely star.

"When one of the stars grows into a red giant, it does not just claim more empty space the way a single star will do," Wolf said. "Instead, it 'embraces' or engulfs its companion, and they appear as one star under an opaque envelope. That's when things get really exciting."

Wolf explains that friction created in the envelope caused by the motion of the stars within it has profound effects on the next step in the evolution of binary stars. "It not only causes heat but slows down the stars, so they spiral into an ever-tighter orbit; the envelope finally overheats and gets blown away," he said.

As a result of this, the stars can end up over 100 times closer together at the end of the common envelope phase than they were at its beginning after heat from the process causes the surrounding matter to be expelled in a violent 'blow-out.'

The blow-out for the binary stars observed by Wolf and colleagues occurred around 10,000 years ago. The researchers predict that the binary stars they observed, now a white dwarf and a hot subdwarf which will eventually evolve into a white dwarf itself, will continue to spiral together eventually merging.

The team's findings and the first glimpse of the aftermath of the common envelope phase of stellar evolution could help other researchers spot more binary stars in the critical stage of their lives.

"It may be easier to recognize them now we have a clearer idea of what to look for. There may be others that have been under our nose the whole time," Wolf said, adding that the findings could also have ramifications for other cosmic unions. "It could even help us better reconstruct gravitational wave events, such as black hole mergers."

The team's research was published in the journal Monthly Notices of the Royal Astronomical Society. (opens in new tab)

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Astronomers witness the rare break up of a star couple - Space.com

The University of Iowa Center for Advancement is posthumously honoring Professor Donald Gurnett with a Distinguished Alumni FacultyAward.

Donald Gurnett,62BSEE, 63MS, 65PHD, was a pioneer in the field of plasma wave research whose innovative instrumentation captured a profusion of data during more than 30 exceptional space research missions, including Voyager, Cassini, and Galileo.

A scientific scholar through and through, the longtime professor in the University of Iowa Department of Physics and Astronomywho died in January 2022also gave generously to ensure the future of space research at Iowa.

James Van Allen's discovery of Earth's radiation belts deepened Gurnett's interest in space plasma physics, inspiring him to join Van Allen's research group. Throughout his extraordinary 60-year career, Gurnett went on to establish the field of space plasma wave research, leading a team that developed numerous plasma wave instrumentsincluding one that proved Voyager I had entered interstellar space. He also mentored more than 60 graduate students and authored or co-authored two textbooks and more than 750 publications.

"Don made tremendous contributions to faculty life, student experience, and research at Iowa," says Philip Kaaret, professor and chair of the university's physics and astronomy department.

Physicists, astronomers, and scientists around the world admire Gurnett, who also was a member of the National Academy of Sciences. He and his wife generously established the Donald A. and Marie B. Gurnett Chair of Physics at the University of Iowa in 2015.

NASA senior advisor James L. Green (79PhD), Gurnet's former student, recognized his professor's leadership in international space researchand his dedication to students: "He advised and mentored an entire generation of graduate students. It is important to recognize his lifetime of excellence and achievements in space science, as well as the service he offered the UI, the planetary science community, and the nation."

Since 1963, the University of Iowa has annually recognized accomplished alumni and friends with Distinguished Alumni Awards. Awards are presented in seven categories: Achievement, Service, Hickerson Recognition, Faculty, Staff, Recent Graduate, and Friend of the University.

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Gurnett Named Distinguished Alumni | Physics and Astronomy - The University of Iowa - The University of Iowa

Yale astrophysicists have helped assemble an unprecedented census of the most powerful, growing supermassive black holes in the universe.

Using data from NASAs Swift satellite and a collection of ground-based telescopes including the ESO Very Large Telescope in northern Chile, the Hale telescope at Palomar observatory in southern California, and the Keck telescope in Hawaii scientists from the BASS Project have collected data for more than 850 growing black holes across the sky.

The BAT AGN Spectroscopic Survey (BASS) Project aims to create a highly complete census of key physical parameters of the supermassive black holes that power local active galactic nuclei (AGNs). Yale astronomers are part of the international group of scientists working on the project.

The new census includes detailed measurements of the emission lines, black hole masses, and distances from Earth for dozens of previously unrecognized systems. The BASS Project has unveiled much of the data in a special issue of the Astrophysical Journal that includes nine research studies drawn from the census.

We joined the BASS Project because of our keen interest in understanding the growth and evolution of supermassive black holes, said C. Megan Urry, the Israel Munson Professor of Physics and Astronomy in the Yale Faculty of Arts and Sciences and director of the Yale Center for Astronomy & Astrophysics. The great instrumentation at the Palomar and Keck telescopes has been crucial for obtaining estimates of black hole masses in this sample, which is by far the largest set of homogeneously selected, well-characterized supermassive black holes.

Supermassive black holes areas of space that have such intense gravity that not even light can escape them have masses between a million and billions of times that of the Sun and are found in the centers of essentially all developed galaxies. Fewer than 10% of these giant black holes are actively growing by swallowing gas from their immediate surroundings.

As the gas nears its final approach to a black hole, the gas heats up and releases intense radiation, which can be detected by astronomers.

Because black holes are found at the center of almost every galaxy, they influence the evolution of galaxies throughout the universe. And yet, particularly in the case of growing, supermassive black holes, they have been difficult to find.

The toughest challenge is that black hole growth is usually heavily obscured by gas and dust, hiding it from most telescopes, Urry said. However, the Burst Alert Telescope aboard the Swift satellite detects these objects at very high X-ray energies and is equally sensitive to obscured and unobscured black holes.

The new BASS dataset used hundreds of nights of data collection on more than 10 telescopes. More than 50 astronomers around the world worked on the project.

Yale contributors included Urry; Lea Marcotulli, a postdoctoral associate in physics; Mislav Balokovi, postdoctoral fellow at the Yale Center for Astronomy and Astrophysics and the Department of Physics; and former Yale graduate students Tonima Ananna, who is now at Dartmouth, and Meredith Powell, who is now at Stanford. Marcotulli is first author of another study that is also part of the collaboration.

Thanks to the large number of systems observed, and the highly complete nature of the survey, we were able to reconstruct the distributions of black hole mass and accretion rate for all sorts of accreting supermassive black holes, said Ananna. We knew for a while that the largest black holes, or those accreting at higher rates, are exceedingly rare, but now we accurately quantified how rare they are, and how common it is to find a more humble black hole, of only several dozen millions of solar masses.

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A new census of supermassive black holes that are growing - Yale News

Inflation will soar to astronomical levels over the next year forcing the Bank of England to raise interest rates higher and for longer than previously expected, according to a leading thinktank.

The National Institute of Economic and Social Research also forecast a long recession that would last into next year and hit millions of the most vulnerable households, especially in the worst-off parts of the country.

NIESR said gas price rises and the escalating cost of food would send inflation to 11% before the end of the year while the retail prices index (RPI), which is used to set rail fares and student loans repayments, is expected to hit 17.7%.

Stephen Millard, the institutes deputy director, said the economy would contract for three consecutive quarters, shrinking the 1% by the spring of next year.

He added there will be no respite for British households and businesses from astronomical inflation in the short term and we will need interest rates up at the 3% mark if we are to bring it down.

As the government faces calls to step in with further support for hard-pressed families, NIESR said average incomes would fall by a record 2.5% this year, leaving millions of families to use savings or expensive credit to pay essential heating and food costs this winter.

In its half-yearly economic health check, the thinktank said the number of households with no savings was set to double to 5.3 million by 2024. Families in the north-east, which rely heavily on public sector jobs, were the most likely to see their savings disappear after using them to pay for day-to-day bills.

The report painted a gloomier picture than most forecasts of the UK economy, which have tended to play down the likelihood of a long period of contraction.

Bank of England officials will give their verdict on the state of the economy on Thursday when the central banks monetary policy committee (MPC) will make its latest decision on interest rates and publish its quarterly review.

Most analysts have pencilled in a majority of the MPCs nine members voting for a 0.5 percentage point increase in the Banks base rate to 1.75%, pushing most mortgage rates to 3.5%.

Concern about the increase in the cost of living this year has become the top issue for households, according to recent polls by Ipsos Mori, and have dominated the debate between the two candidates vying for the leadership of the Conservative party.

In May, the Bank said inflation would rise slightly above 10% and fall quickly as interest rates of about 2% began to depress consumer demand.

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NIESR said it expected the Bank to continue hiking rates until they reached 3% and keep them in place for longer than previously expected to bring inflation down to 3% by the end of next year.

While about 80% of mortgage borrowers are on fixed rate products, millions of them will need to remortgage to higher interest rates over the next year. Higher mortgage rates also feed into private rental costs, which have already risen sharply in recent years.

The thinktank said below inflation wage rises would become entrenched and by 2026 would mean that real incomes, after inflation is taken into account, would be 7% below the pre-Covid trend.

Jagjit Chadha, the director of NIESR, said the incoming prime minister should focus economic policy on redistributing resources to the most financially vulnerable households and maintain public services.

He said it made economic sense to protect vulnerable families, renewing the institutes call for a rise in Universal Credit payments of 25 per week at a cost of 1.35bn from October 2022 to March 2023.

The government should also raise the energy grant from 400 to 600 for 11 million low-income households, at a total cost of 2.2bn, he said.

Chadha added that to turn some of the levelling up rhetoric into reality, the government should consider doubling the financial support for the Towns Fund from 4.8bn to 9.6bn and expand the remit of the UK Infrastructure Bank; increasing its capital from 14bn to 50bn.

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UK inflation will soar to astronomical levels over next year, thinktank warns - The Guardian

Astronomers have discovered a 'super-Earth' orbiting a red dwarf star just 37 light-years from our solar system.

The exoplanet Ross 508 b skims the so-called habitable zone of its parent star, the area in which surface temperatures are suitable to allow for the existence of liquid water, a key ingredient of life. The newly discovered exoplanet has about four times the mass of Earth and was discovered using a new infrared monitoring technique. The proximity of this super-Earth to our planet means it is ripe for atmospheric investigation, which could help researchers determine whether life could exist around low-mass stars.

"To have the very first planet discovered by this new method be so tantalizingly close to the habitable zone seems too good to be true and bodes well for future discoveries," team leader and Tokyo Institute of Technology professor Bun'ei Sato said in a statement.

Related: These 10 super extreme exoplanets are out of this world

Red dwarfs like Ross 508, which has about one-fifth of the mass of the sun, are small stars that account for around three-quarters of all stars in our galaxy, the Milky Way. These stars are especially abundant in the region around our solar system, making red dwarf stars and their systems ideal targets for the search for planets outside the solar system and the investigation of possible life elsewhere in the universe.

The fact that red dwarfs are small means that they are cool, with temperatures of between 2,000 and 3,500 Kelvin. Their relatively low temperatures make them dim in visible light, unlike larger stars, and means astronomers must study them in infrared.

In order to do this, the Astrobiology Center in Japan developed an infrared observational instrument called the InfraRed Doppler instrument (IRD) to mount on the Subaru Telescope in Hawai'i. With this instrument the world's first high-precision infrared spectrograph for an 8-meter class telescope the astronomers set about searching for signs of planets around red dwarf stars.

Specifically, the researchers looked for the tell-tale 'wobble' that an exoplanet causes in the orbit of its parent star; the wobble registers as a tiny shift in the wavelength of light from the star as it moves toward and away from Earth.

The discovery of Ross 508 b marks the first success for the project, which is officially named the IRD Subaru Strategic Program (IRD-SSP).

"It has been 14 years since the start of IRD's development," Sato said. "We have continued our development and research with the hope of finding a planet exactly like Ross 508 b."

Ross 508 b, just the third planet to be found around such a low-mass star, has an average distance from its parent star of just one-twentieth times the distance between Earth and the sun. The astronomers who discovered it believe that the planet's highly elliptical orbit carries it into Ross 508's habitable zone every 11 days.

"Ross 508 b is the first successful detection of a super-Earth using only near-infrared spectroscopy," Subaru Telescope researcher Hiroki Harakawa said in the statement. "Prior to this, in the detection of low-mass planets such as super-Earths, near-infrared observations alone were not accurate enough, and verification by high-precision line-of-sight velocity measurements in visible light was necessary." (Although super-Earths are larger than our own planet, most of the exoplanets scientists are currently detecting are much larger.)

Harakawa added that the study, for which he was the lead author, shows that even acting alone IRD-SSP is capable of detecting planets. He said the work especially demonstrates the advantage of IRD-SSP in its ability to detect planets with high precision even around late-type red dwarfs that are too faint to be observed with visible light.

The team's research was published June 30 in the journal Publication of the Astronomical Society of Japan (PASJ).

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Super-Earth planet zips through the habitable zone of red dwarf star - Space.com

Students can get a head start on an aerospace career by entering the 2023 CanSat Competition.

Not just a paper exercise, CanSat is an annual competition in which college and university teams from around the world participate in a scored and judged design-build-launch project to see who can best meet assigned mission requirements. From conceptual design, through integration, test, and flight, teams engineer, create, and actually launch payloads in a challenging and rewarding test of knowledge, skills, project management, and teamwork.

Since 2005, the CanSat Competition, organized by the American Astronautical Society (AAS) alongside the U.S. Naval Research Laboratory (NRL) has organized an annual student design-build-launch competition for space-related topics. Throughout the years, NRL has been devoted to supporting CanSat in its efforts to further students aerospace exploration through the development of aeronautical exploration and STEM education.

If you are interested in participating in the CanSat, please log onto:www.cansatcompetition.comor contact NRL Corporate Communications at (202)-480-3746 ornrlpao@nrl.navy.mil. The American Astronautical Society (AAS) contact is Jim Way atjimway@astronautical.org

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CanSat Annual Competition Open to Students | Physics and Astronomy - The University of Iowa - The University of Iowa

A sample dwarf galaxy (small box left) observed with the Ultraviolet Imaging Telescope on AstroSat. AstroSat detected extremely blue star-forming clumps on the galaxy's outer boundary (box on left)

Dwarf galaxies, made up of a few billion stars at most, have been the object of fascination for many astronomers. They offer a window into the evolution of the universe's early galaxies. Studying star formation and assembly in these small, irregular galaxies can offer insights into how modern-day galaxies, like our own Milky Way Galaxy, evolved.

But observing BCDs in their developmental phase is extremely challenging since they remain very faint and faraway, lost in the infinite cosmos. Now, an international team of researchers have managed to track the birth of new stars on the periphery of these faraway dwarf galaxies using the Indian Ultra-Violet Imaging Telescope AstroSatIndia's first dedicated multi-wavelength satellite telescope designed to investigate celestial sources.

Capturing the assembly process in dwarf galaxies is considered important because the diversity in their physical properties observed today challenge the current theoretical models of galaxy evolution. AstroSat/UVIT has been a remarkable addition to the list of UV observatories to date and has opened up promising windows to probe the understanding of the galaxy assembly process, explains Anshuman Borgohain, an astronomer from Tezpur University, Assam, and lead author of the study.

Professor Kanak Saha at Pune's Inter-University Centre for Astronomy and Astrophysics (IUCAA) conceived the study involving astronomers from India, the US and France. They have come one step closer to understanding how stars come to be in dwarf galaxies through this research. New stars in the distant dwarf galaxies, called Blue Compact Dwarf galaxies or BCDs, are known to migrate inwards towards their centre, contributing to the galaxies' mass and volume.

Using AstroSat, the scientists discovered these star production zones in eleven BCDs! The findings of this research showed how "extended star formation" plays a role in the formation of dwarf galaxies.

We are witnessing the live formation of these far-way dwarf galaxies! AstroSat's resolving power, and deep field imaging techniques have been the key to spotting some very young, large star-forming clumps. These form on the periphery and then spiral into the visible (optical) boundary of their galaxy within a billion years timescale, thus adding to the growth of the galaxy, said Prof Saha.

Further, this study reports the discovery of extensive far-ultraviolet (FUV) discs in distant dwarf galaxies for the first time. To simply put it, our home-grown AstroSat detects far-off objects using ultraviolet, X-ray, and visible light, while NASA's James Webb Space Telescope analyses distant galaxies in various infrared wavelengths.

**

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Indias AstroSat Telescope Helps Astronomers Observe Star Formation in Distant Dwarf Galaxies - The Weather Channel

We have all seen many kinds of clouds -- rain clouds, white puffy clouds, clouds with rainbows, even clouds of gnats and steam clouds from an old-fashioned locomotive I saw when I was a child.

Have you ever seen a cloud of stars? I have -- in the summer Milky Way.

Our galaxy is a spiral galaxy about 120,000 light-years across -- more or less -- it's hard to measure a galaxy when you are in the middle of it.

All spiral galaxies are dirty. That is, they contain a great deal of dust and gas that is not anything else but dust and gas. Sometimes the patches of dust are so black and dense they can block the stars behind them, just as the moon can be hidden by thick clouds.

Good photography of the Milky Way became possible around the turn of the 19th to the 20th century. When scientists began to photograph our galaxy, they noticed great dark patches that, in places, were very black.

A controversy arose as to what these black patches were. Two ideas competed. The first idea was that these dark patches were places where stars simply did not form. However, no one could imagine why stars did not form in these black spaces while enormous numbers of them formed right next to the black patches. A second idea was that the dark places were formed by enormous spots of dense dust and gas and these kept astronomers from seeing the stars behind them.

A very great American astronomer, E.E. Barnard, essentially self-taught, speculated about the dark patches and proposed that the dark patches were clouds of dense, black dust. Using a 10-inch camera and the fastest film, Barnard took images of a large number of these "dark nebula" and published several copies of his actual photographic prints bound as a book. (An original copy of Barnard's work is quite rare and valuable.)

Those scientists, including Barnard, who thought the dark patches were clouds of dust that hid the stars behind them, were correct. Obscuring nebula turn out to be present in all the spiral galaxies we can photograph now.

So, there are the clouds we see in the daytime, in our atmosphere, and there are clouds of stars and dust that can be seen with a telescope or photographed with a camera.

I have included an image of a cloud of stars I have made with a very fast telephoto lens. This cloud of stars has a name -- the Scutum Star Cloud. It is often photographed by amateurs because of its mysterious beauty. There are hundreds of thousands of stars in this image, making the cloud. Interwoven among these stars one can see lines and spots of obscuring dust.

If one stays up late, Saturn can be seen rising in the southeast. Staying up to about midnight, one can see Jupiter just at the eastern horizon. As the year moves on, these two planets, as well as Mars, can be seen in the mid-evening hours.

At a dark observing site, look for the Milky Way, nearly overhead. Get out those binoculars and see if you can see clouds of stars -- and dark clouds too.

Don't miss the Perseid Meteor Shower on the night of Aug. 12-13. All you need to do is stay up late and use just your eyes.

David Cater is a former faculty member of JBU. Email him at [emailprotected] The opinions expressed are those of the author.

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ASTRONOMY: Clouds Of Stars And Dust - Mdcp.nwaonline.com

As the stars move across the sky each night people of the world have looked up and wondered about their place in the universe. Throughout history civilizations have developed unique systems for ordering and understanding the heavens. Babylonian and Egyptian astronomers developed systems that became the basis for Greek astronomy, while societies in the Americas, China and India developed their own.

Ancient Greek astronomers' work is richly documented in the collections of the Library of Congress largely because of the way the Greek tradition of inquiry was continued by the work of Islamic astronomers and then into early modern European astronomy. This section offers a tour of some of the astronomical ideas and models from ancient Greece as illustrated in items from the Library of Congress collections.

By the 5th century B.C., it was widely accepted that the Earth is a sphere. This is a critical point, as there is a widespread misconception that ancient peoples thought the Earth was flat. This was simply not the case.

In the 5th century B.C., Empedocles and Anaxagoras offered arguments for the spherical nature of the Earth. During a lunar eclipse, when the Earth is between the sun and the moon, they identified the shadow of the Earth on the moon. As the shadow moves across the moon it is clearly round. This would suggest that the Earth is a sphere.

Given that opportunities for observations of a lunar eclipse do not come along that often, there was also evidence of the roundness of the earth in the experiences of sailors.

When a ship appears on the horizon it's the top of the ship that is visible first. A wide range of astronomy texts over time use this as a way to illustrate the roundness of the Earth. As the image suggests this is exactly what one would expect on a spherical Earth. If the Earth were flat, it would be expected that you would be able to see the entire ship as soon as it became visible.

Lunar eclipses also allowed for another key understanding about our home here on Earth. In 3rd Century B.C., Aristarchus of Samos reasoned he could figure out the size of the Earth based on information available during a lunar eclipse. The diagram at the right illustrates a translation of his work. The large circle is the sun, the medium circle is the Earth and the smallest circle is the moon. When the Earth is in-between the sun and the moon it causes a lunar eclipse and measuring the size of the Earth's shadow on the moon provided part of the information he needed to calculate its size.

Eratosthenes estimated Earth's circumference around 240 B.C. He used a different approach, measuring the shadows cast in Alexandria and Syene to calculate their angle relative to the Sun. There is some dispute on the accuracy of his calculations as we don't know exactly how long the units of measure were. The measurement however was relatively close to the actual size of the Earth. The Greeks were applying mathematics to theorize about the nature of their world. They held a range of beliefs about nature and the world but they were, in many cases, working to ground those beliefs in an empirical exploration of what they could reason from evidence.

In the tradition of Plato and Empedocles before him, Aristotle argued that there were four fundamental elements, fire, air, water and earth. It is difficult for us to fully understand what this meant as today we think about matter in very different terms. In Aristotle's system there was no such thing as void space. All space was filled with some combination of these elements.

Aristotle asserted that you could further reduce these elements into two pairs of qualities, hot and cold and wet and dry. The combination of each of these qualities resulted in the elements. These qualities can be replaced by their opposites, which in this system become how change happens on Earth. For example, when heated, water seemingly turns steam which looks like air.

In Aristotle's Cosmology, each of these four elements (earth, water, fire and air) had a weight. Earth was the heaviest, water less so, and air and fire the lightest. According to Aristotle the lighter substances moved away from the center of the universe and the heaver elements settled into the center. While these elements attempted to sort themselves out, to achieve this order, most of experience involved mixed entities.

While we have seen earth, fire, air and water, everything else in the world in this system was understood as a mixture of these elements. In this perspective, transition and change in our world resulted from the mixing of the elements. For Aristotle the terrestrial is a place of birth and death, based in these elements. The heavens are a separate realm governed by their own rules.

In contrast to the terrestrial, the celestial region of the heavens had a fundamentally different nature. Looking at the night sky the ancient Greeks found two primary kinds of celestial objects; the fixed stars and the wandering stars. Think of the night's sky. Most of the visible objects appear to move at exactly the same speed and present themselves in exactly the same arrangement night after night. These are the fixed stars. They appear to move all together. Aside from these were a set of nine objects that behaved differently, the moon, the sun and the planets Mercury, Venus, Mars, Saturn and Jupiter each moved according to a different system. For the Greeks these were the wandering stars.

In this system the entire universe was part of a great sphere. This sphere was split into two sections, an outer celestial realm and an inner terrestrial one. The dividing line between the two was the orbit of the moon. While the earth was a place of transition and flux, the heavens were unchanging. Aristotle posited that there was a fifth substance, the quintessence, that was what the heavens were made of, and that the heavens were a place of perfect spherical motion.

In Aristotle's words, "In the whole range of time past, so far as our inherited records reach, no change appears to have taken place either in the whole scheme of the outermost heaven or in any of its proper parts." It's important to keep in mind that in Aristotle's time there simply were not extensive collections of observational evidence. Things that looked like they were moving in the heavens, like comets, were not problematic in this model because they could be explained as occurring in the terrestrial realm.

This model of the heavens came with an underlying explanation. The celestial spheres were governed by a set of movers responsible for the motion of the wandering stars. Each of these wandering stars was thought to have an "unmoved mover" the entity that makes it move through the heavens. For many of the Greeks this mover could be understood as the god corresponding to any given entity in the heavens.

Claudius Ptolemy (90-168) created a wealth of astronomical knowledge from his home in Alexandria, Egypt. Benefiting from hundreds of years of observation from the time of Hipparchus and Eudoxus, as well as a set of astronomical data collected by the Babylonians, Ptolemy developed a system for predicting the motion of the stars that was published in his primary astronomical work, Almagest. Ptolemy's success at synthesizing and refining ideas and improvements in astronomy helped make his Almagest so popular that earlier works fell out of circulation. Translated into Arabic and Latin the Almagest became the primary astronomy text for the next thousand years.

The Almagest is filled with tables. In this sense the book is a tool one can use to predict the locations of the stars Compared to earlier astronomy the book is much more focused on serving as a useful tool than as presenting a system for describing the nature of the heavens. Trying to accurately predict the place of the stars over time resulted in creating a much more complicated model.

By the time of Ptolemy Greek astronomers had proposed adding circles on the circular orbits of the wandering stars (the planets, the moon and the sun) to explain their motion. These circles on circles are called epicycles. In the Greek tradition, the heavens were a place of perfect circular motion, so the way to account for perfection was with the addition of circles. This resulted in disorienting illustrations.

To escape the complicated nature of this extensive number of circles, Ptolomy added a series of new concepts. To accurately describe planetary motion, he needed to use eccentric circles. With the eccentric circle the center of the planets orbit would not be Earth but would instead be some other point. Ptolemy then needed to put the epicycles on another set of circles called deferents. So the planets moved on circles that moved on circular orbits. Ptolomy also needed to introduce equants, a tool that enabled the planets to move at different speeds as they moved around these circles. The resulting model was complex, but it had extensive predictive power.

Ptolemy came to represent a mathematical tradition, one focused on developing mathematical models with predictive power. Aristotle came to be known for putting forward the physical model of the heavens. Ptolemy was also interested in deploying his model of the heavens to describe its physical reality. However, his most important work was the mathematical models and data he used for predicting the motion of heavenly bodies. For a long time his name was synonymous with the model of the heavens.

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TEHRAN-The historical oasis city of Yazd is scheduled to host an astronomy tour on Saturday to mark the 5th registration anniversary of the city on the UNESCO World Heritage list, a local tourism chief has said.

The two-day tour will be held in the heart of the historical structure of the Iranian city and will be free for astronomy enthusiasts, Mehdi Mahajan explained on Friday.

Yazd's clear sky and desert environment make it an ideal destination for astronomical tourism, the official added.

Among the popular types of tourism, astronomical tourism has become more known and introduced in recent years, attracting both domestic and foreign tourists, he noted.

The economy of astronomical tourism can be very successful and attention and emphasis can be paid to its development as a way to grow and develop tourism in Yazd, he mentioned.

In July 2017, the historical structure of the city of Yazd was named a UNESCO World Heritage. Wedged between the northern Dasht-e Kavir and the southern Dasht-e Lut on a flat plain, the oasis city enjoys a very harmonious public-religious architecture that dates from different eras.

Yazd is usually referred to as a delightful place to stay, or a don't miss destination by almost all of its visitors. The city is full of mudbrick houses that are equipped with innovative badgirs (wind catchers), atmospheric alleyways, and many Islamic and Iranian monuments that shape its eye-catching city landscape.

It is a living testimony to the intelligent use of limited available resources in the desert for survival. Water is brought to the city by the qanat system. Each district of the city is built on a qanat and has a communal center.

Astronomical tourism represents a less-studied segment of sustainable tourism, where a dark night sky is an underlying resource, and this branch of tourism could lead to sustainable development in rural areas.

Illuminated only by the stars and having a clear sky, Iranian deserts are dream places for astronomy enthusiasts and sky lovers to experience dark night observatories.

The country is home to wide deserts in its central lands including UNESCO-tagged Lut Dessert as well as several historical caravanserais hosting astronomical tourists from ancient eras to the present.

ABU/MG

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Yazd to host astronomy tour to mark World Heritage registration anniversary - Tehran Times

A star has been found with the shortest known orbit around Sgr A*, the supermassive black hole in the center of our galaxy: It takes just four years to orbit the behemoth once.

The star, called S4716, is part of a cluster of massive stars only discovered relatively recently centered on the black hole in the Milky Ways heart. Over time, as these stars move in their orbits, their positions can be measured to determine their orbits, and from there key characteristics of the black hole itself can be found.

Sgr A*, you may recall, was the subject of a recent series of observations using radio telescopes across the world to get an image of the matter in an accretion disk swirling around it. That material is only about 60 million kilometers from the black hole not much farther than Mercury is from the Sun. The stars in the cluster, however, are many billions of kilometers from it at their closest, and range as far as about a tenth of a light year out, or roughly a trillion kilometers.

The individual stars in the S Cluster, as its called, are hard to observe for many reasons. One is simply due to how close they are together and how far they are from Earth. Even with our biggest telescopes the stars can appear to overlap, causing confusion. Theres also a lot of dust swirling around in the galactic center, dimming the view. Thats why astronomers tend to use telescopes designed to see in infrared light, which can penetrate the dust and give us a clearer view. Even then, observations like these are hard.

Making things worse is S2, the brightest star in the cluster, which tends to swamp the light of nearby stars. So finding stars that are fainter and close to the black hole is tough.

Using various cameras on the immense Keck and Very Large Telescopes, a team of astronomers looked at data taken over the past two decades of Sgr A* [link to paper]. Using sophisticated techniques to clean and sharpen the images, they see a previously undiscovered star they call S4716 in images taken over 16 different observation periods. The star can be seen to move around the black hole on a decently elliptical orbit (with an eccentricity of about 0.75 for you geometry nerds) with a period of about 4 years.

It passes as close as 1.5 billion kilometers from Sgr A*, which is pretty close about the distance of Saturn from the Sun and gets about 10 billion kilometers out at its farthest, which is roughly twice the distance of Neptune from the Sun.

Given the huge gravity of the black hole, that means the star moves at a staggering 28 million kilometers per hour at closest approach: Thats 2.6% the speed of light. Yegads.

Amazingly, thats actually not the fastest star orbiting Sgr A*! A star found a few years ago, called S4714, is on a very elliptical orbit that accelerates it to a speed of about 85 million km/hr, or 8% the speed of light. That stars orbit stretches very long, taking it much farther out from the black hole, and its period is more like 12 years long. So, for the moment, S4716 holds the record for shortest and most compact orbit of any star around Sgr A*.

S4716 is a big star, about four times the mass of the Sun and some 130 times as luminous; good thing or it would be impossible to spot. Its orbit depends on the mass of the black hole and its distance, so using the centuries-old equations for orbital motion they can calculate the mass of Sgr A*, and get a value of 4.023 0.087 million times the Suns mass, which is in line with previous measurements.

They can also get the distance to the black hole, and find it to be 26,170 650 light-years from us. That too is consistent with previous measurements. Thats nice to know. And these numbers are one reason astronomers are eager to spot these stars, as they can constrain what we know about the black hole.

The S Cluster itself is a mystery, too. Its not clear how it formed, since gas that close to the black hole would be heated too much to collapse and form massive stars. Its likely they formed farther out and dropped in closer to Sgr A* through close gravitational encounters with other stars, a process called mass segregation. The more stars found and analyzed in the cluster, the better well understand its history.

Observations like these are on the bleeding edge of what can currently be done. Its possible JWST will be able to help here; as an infrared telescope it can see past the dust, and its sharp vision may help with separating the mess of stars swirling in the galactic core.

The Milky Ways center is maelstrom of gas, dust, stars, powerful magnetic fields, and of course a monster black hole right at the very heart of it all. But, with persistence and patience, order is being teased out of the chaos.

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Newly discovered star takes just four years to orbit Sgr A*, our local supermassive black hole - Syfy