Category Archives: Astronomy

February 16, 2022 marked the 66th death anniversary of Indian astrophysicist Meghnad Saha, who is widely renowned for his 'Saha ionisation equation', mainly used to describe physical and chemical conditions in stars. It is also thanks to Saha's work astronomers can accurately relate the spectral classes of stars to their actual temperatures.

The late astrophysicist's research work on the thermal ionisation of elements led him to come up with what is now known as the Saha equation. As per the equation, it is the basic tool for interpreting the spectra of stars in astrophysics. Through the study of the ranges of various stars, one can find their temperature and, using Saha's equation, determine the ionisation state of the various elements making up the star. His work was also soon extended by Edward Arthur Milne and Ralph H. Fowler, as per Wikipedia.

Meghnad Saha also was the one who invented an instrument to measure the pressure and weight of solar rays and assisted in building numerous scientific institutions, such as the Institute of Nuclear Physics in Calcutta and the Physics Department in Allahabad University. The late astrophysicist founded the journal Science and Culture and was also the editor until he passed away.

Furthermore, Saha was also the leading spirit in organising several scientific societies, such as the Indian Institute of Science (1935), the Indian Physical Society (1934), National Academy of Science (1930). The visionary Indian was also the Director at the Indian Association for the Cultivation of Science between 19531956. Founded in 1943, the Saha Institute of Nuclear Physics in Kolkata is named after him as well.

Born on October 6, 1893, in Shaoratoli, a small village near Dhaka, in the former Bengal Presidency of British India (now Bangladesh), Meghnad Saha struggled to rise in life and was forced to leave Dhaka Collegiate School due to his participation in the Swadeshi movement.

Saha died on February 16, 1956, at the age of 62, due to a cardiac arrest in New Delhi while he was on his way to the office of the Planning Commission in Rashtrapati Bhavan. He reportedly collapsed a few yards away from there and passed away on the way to the hospital at 10:15 a.m. (IST).

Furthermore, reports also revealed that he had been suffering from hypertension for ten months before his death. His remains were cremated at the Keoratola crematorium in Kolkata the following day.

Also Read: Drones Made By IIT-Delhi-Incubated Startup Lit Up Sky At Beating Retreat Ceremony

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Meghnad Saha: Indian Astrophysicist Who Revolutionised Astronomy With His Saha Ionisation Equation - The Logical Indian

University of Arizona astronomy students are tracking the object projected to crash into the Moon later this spring.

UA planetary sciences professor Vishnu Reddy says his students met the challenge of confirming the object is a spent booster stage of a Chinese rocket launched in 2014.

We observed it with a telescope on campus and were able to compare similar boosters left in Earth orbit by other missions," explained Reddy. "We compared one from Space X and one from the Chinese mission and it turns out we got a pretty good match.

Scientists predict the rocket stage will impact the far side of the Moon in early March.

It wont be visible from Earth, but Reddy says astronomers are aiming to get photographs of the eventual crash site from the Lunar Reconnaissance Orbiter already circling the Moon.

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University of Arizona astronomy researchers track space junk to the Moon - Arizona Public Media

Representative Image

A team of astronomers using the European Southern Observatory's Very Large Telescope (ESO's VLT) in Chile have found evidence of another planet orbiting Proxima Centauri, the closest star to our Solar System.

Proxima Centauri is located over four light-years away. The newly discovered planet, named Proxima d, orbits Proxima Centauri at a distance of about four million kilometres, less than a tenth of Mercury's distance from the Sun.

This candidate planet is the third detected in the system and the lightest yet discovered orbiting this star. At just a quarter of Earth's mass, the planet is also one of the lightest exoplanets ever found.

These findings are published in Astronomy & Astrophysics journal.

"The discovery shows that our closest stellar neighbour seems to be packed with interesting new worlds, within reach of further study and future exploration," said Joao Faria, a researcher at the Instituto de Astrofisica e Ciencias do Espaco, Portugal, in a statement.

Proxima d orbits between the star and the habitable zonethe area around a star where liquid water can exist at the surface of a planetand takes just five days to complete one orbit around Proxima Centauri.

The star system is already known to host two other planets: Proxima b, a planet with a mass comparable to that of Earth that orbits the star every 11 days and is within the habitable zone, and candidate Proxima c, which is on a longer five-year orbit around the star.

Proxima b was discovered a few years ago using the HARPS instrument on ESO's 3.6-metre telescope.

The discovery was confirmed in 2020 when scientists observed the Proxima system with a new instrument on ESO's VLT that had greater precision, the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO).

It was during these more recent VLT observations that astronomers spotted the first hints of a signal corresponding to an object with a five-day orbit. As the signal was so weak, the team had to conduct follow-up observations with ESPRESSO to confirm that it was due to a planet, and not simply a result of changes in the star itself.

"After obtaining new observations, we were able to confirm this signal as a new planet candidate," Faria said.

At just a quarter of the mass of Earth, Proxima d is also the lightest exoplanet ever measured using the radial velocity technique, surpassing a planet recently discovered in the L 98-59 planetary system.

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The above article has been published from a wire source with minimal modifications to the headline and text.

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Astronomers Discover New Planet Orbiting Sun's Closest Star | The Weather Channel - Articles from The Weather Channel | weather.com - The Weather...

Science | UW News blog

February 9, 2022

Starlink Satellites pass overhead near Carson National Forest, New Mexico, photographed soon after launch.M. Lewinsky

For many people, the night sky is a beautiful sight. But to astronomers, the night sky is becoming louder, brighter and busier to the point of drowning out the cosmos that they seek to study.

Satellite constellations are one of the main culprits. These are networks of satellites launched in recent years into low Earth orbit for applications such as broadband networks. The satellite constellations in place are already interfering with astronomical observations, with private companies planning to hoist thousands more in the coming decade.

At a press conference on Feb. 3, the International Astronomical Union launched the Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference to be hosted jointly by the National Science Foundations NOIRLab and the U.K.-headquartered Square Kilometre Array Observatory. The center will coordinate collaborative multidisciplinary international efforts with institutions and individuals including researchers at the University of Washingtons Data Intensive Research in Astrophysics and Cosmology Institute, or DiRAC Institute and will work across multiple geographic areas to help mitigate the negative impacts of satellite constellations on ground-based optical and radio astronomy observations as well as humanitys enjoyment of the night sky.

Satellite constellations introduce large amounts of noise into images and data collection runs by Earth-based observatories. For example, they reflect sunlight, and appear as streaks across images of cosmic objects. That does more than ruin a good picture: The streaks can obscure objects and reduce the scientific utility of astronomical images. In addition, their uplink and downlink transmissions can interfere with radio astronomy.

Were witnessing a new era as skies fill with thousands of bright satellites, said Meredith Rawls, a research scientist with the Vera C. Rubin Observatory and the DiRAC Institute at the UW. In just the last two years, astronomers have realized this will impact our ability to achieve science goals from ground-based facilities like Rubin Observatory.

DiRAC is a supporter of the new center, and Rawls spoke at the press conference about the critical need to understand the impact satellite constellations will have on astrophysical research and other endeavors, such as identifying and tracking potentially hazardous near-Earth asteroids.

There is no limit on the number or brightness of satellites streaking across the night, and as a result, not only is science impacted, but so are astronomers careers and the shared human experience of a dark sky, said Rawls.

This image of Venus and the Pleiades shows tracks from Starlink satellites. The reflective surfaces of the satellites, coupled with the fact that they are orbiting around Earth, mean that astronomical observations that require very long exposures capture tracks of the satellites in their images.T. Hansen/IAU OAE

In 2020, Rawls began studying interference from SpaceXs Starlink satellites, which are part of a network to market broadband access to underserved regions. She leads the Trailblazer Project, which will be an online repository for images with satellite interference. Dino Bekteevi, a UW graduate student in astronomy, is working with Rawls on the project, along with undergraduate students at the UW and other institutions. Trailblazer will contribute to one of the new centers core aims: the creation of a SatHub platform to coordinate the sharing, analysis and dissemination of images with streaks and other interference caused by satellites.

We are building Trailblazer to be an open data repository for astronomical images with satellite streaks, with two goals: giving astronomers with messed-up images something useful to do with them; and enabling studies of how the rapidly-changing satellite population is actually impacting ground-based optical/near-infrared astronomy, said Rawls.

The center has other hubs for community engagement and advocating for new policies and regulations, as well as for interfacing with private companies and government agencies.

The International Astronomical Union called for the establishment of the center in 2021. It aims to bring together astronomers, satellite operators, regulators and the wider community and acts as a bridge among all stakeholders to protect the dark and quiet skies. The center builds on the vast amount of work carried out by the two host institutions, along with other supporting institutions across the world like the DiRAC Institute.

The new center is an important step towards ensuring that technological advances do not inadvertently impede our study and enjoyment of the sky, said IAU President Debra Elmegreen. I am confident that the center co-hosts can facilitate global coordination and bring together the necessary expertise from many sectors for this vital effort.

The vision of the center is to become the leading voice for astronomical matters that relate to the protection of the dark and quiet sky from satellite constellations and to act as a hub of information and resources for stakeholder groups.

Continuing to preserve a dark and quiet sky is essential for both astronomy and for sustaining the curiosity of future generations, who find inspiration from simply looking up, said Matt Mountain, president of AURA, which operates NOIRLab under a cooperative agreement with the NSF.

For more information, contact Rawls at mrawls@uw.edu.

Adapted from a press release by NSFs NOIRLab.

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New IAU center to focus on solutions to satellite interference in astronomical observations - UW News

Home Technology Web Space Telescope will create an age of astronomy where observation leads the theory : Dong-A Science February 15, 2022 Interview with Senior Researcher Sang-mo Som, at the US Space Telescope Research Center, If you send a robot to L2 within 10 to 20 years, the life of the telescope could be extended further

If robots are sent to L2 within 10 to 20 years, the lifespan of telescopes may be further extended

Until now, astronomy has been an era in which theory drives observation and advances observations. We are cautiously anticipating that in the future, the Webb Space Telescope will transform into an era in which observations drive theory.

Sangmo Som, a senior researcher at the US Space Telescope Research Institute (STScI), who participated in the James Webb Space Telescope (Web Space Telescope) development project, which went into space on December 25 last year, revealed this prospect in an email interview with Yonhap News on the 15th.

The Hubble Space Telescope (operated since 1990) has had a profound impact on the development of modern astronomy, said Sohn, senior researcher.

He emphasized, If an appearance or phenomenon in the universe that astronomers did not expect at all (via the Web Space Telescope) is observed, it can serve as an opportunity to establish a new theory to explain it.

After graduating from Yonsei Universitys Department of Astronomy and Space, he received his masters and doctoral degrees from the University of Virginia, USA.

Currently, he is responsible for the mirror alignment of the Webb Space Telescope.

(Seoul = Yonhap News) Web space telescope mirror made of 18 pieces [NASA/Chris Gunn ]

The Webb Space Telescopes mirror consists of 18 pieces glued together in a honeycomb shape. Mirror alignment refers to precisely moving these pieces to act like a single mirror with a diameter of 6.5m.

STScl, where he works, is a space telescope specialized research institute that is in charge of the operation of NASAs giant space telescope project. He has been responsible for the operation of the Hubble Space Telescope for the past 30 years, and all operations after the launch of the Webb Space Telescope are also managed by STScl.

It was the most memorable day of my life, said senior researcher Sohn, who worked on the Hubble Space Telescope team and joined the Webb Space Telescope project in 2019.

He recalled, It was Christmas morning, and I was more excited than my two children who received Christmas presents.

Senior Researcher Sohn said, When the Webb Space Telescope arrived at the target orbit of the 2nd Lagrange point (L2) on the 25th of last month, the researcher was engulfed in a very encouraging atmosphere. Were working hard on one, he said of STScls mood.

According to his explanation, the current Webb Space Telescope has successfully completed solar panels, sun shields, and mirror deployments, and has passed an important hurdle before stable observations can be made.

The Webb Space Telescope is very busy performing the mirror alignment process, he said. On the back of each sculpted mirror, a device that enables fine adjustment with precision in the order of 10 nanometers (nm) is installed, which requires a high degree of precision. It is a very complex task, so it takes place over a long period of three months.

He said that the Webb Space Telescope is going through a very smooth process after launch, but this is the result of overcoming numerous difficulties and obstacles several times.

He said he was very frustrated at the thought of having to start all over again whenever a launch was delayed, and mentally exhausted as all teams had to re-plan for that date when a new launch date was announced, he said.

(AFP = Yonhap News) The National Aeronautics and Space Administration (NASA) announced on the 24th (local time) that the James Webb Telescope (JWST), which was launched on a rocket at the end of last year, successfully entered its target orbit 1.6 million km away from Earth. announced. This next-generation Webb telescope, which will provide the furthest and deepest look into space, is expected to play an important role in confirming the appearance of the universe immediately after the Big Bang and in finding exoplanets that may contain life. Pictured is an image of the James Webb Telescope placed in space observation orbit. [NASA ] 2022.1.25 [emailprotected]

After launch, there were 344 single points of failure (an element that stops the whole if one of the components does not work) while the Webb Space Telescope flew to the L2 point, including the launch, said senior researcher Sohn. There were a lot of team members who breathed a sigh of relief every time, he said.

He predicted that as the Webb Space Telescope went up to the sky after thorough preparation, its lifespan would be longer than expected, and it could produce results beyond imagination.

The Webb Space Telescopes near-perfect entry into its target orbit saved fuel as much as possible, and recent calculations have increased its life expectancy to more than 20 years, he said. I need a dog, but I installed six in case of a breakdown.

He also said, It is still too early to have hope, but there is talk of whether NASA will send a robot to L2 orbit within 10 to 20 years to further extend the lifespan of the Webb telescope, he said.

He emphasized the importance of continuous interest and support for space science and astronomy, saying that the development of the space telescope has created various technologies that improve the quality of our real life as well as the development of pure science.

He said, The universe is not a vague object of admiration, but a space where anyone can realize a specific dream through a scientific method. expected.

yunhap news

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Web Space Telescope will create an age of astronomy where observation leads the theory : Dong-A Science - The Times Hub

The number of planets discovered beyond our Solar System has grown exponentially in the past twenty years, with 4,919 confirmed exoplanets (and another 8,493 awaiting confirmation)! Combined with improved instruments and data analysis, the field of study is entering into an exciting new phase. In short, the focus is shifting from discovery to characterization, where astronomers can place greater constraints on potential habitability.

In particular, the characterization of exoplanet atmospheres will allow astronomers to determine their chemical makeup and whether they have the right characteristics to support life. In a new study led by the University of Lund, an international team of researchers characterized the atmosphere of one of the most extreme exoplanets yet discovered. This included discerning what could be several distinct layers that have particular characteristics.

The study, which recently appeared in the journal Nature Astronomy, was conducted by researchers from the Lund Observatory (University of Lund), the National Centre of Competence in Research (NCCR) PlanetS, the Max Planck Institute for Extraterrestrial Physics, the National Institute for Astrophysics (INAF), the European Southern Observatory (ESO), and multiple universities and research institutes from the UK, Canada, and Chile.

As Earths atmosphere demonstrates, planetary atmospheres do not consist of a single uniform envelope but many layers, each with characteristic properties. The lowest layer of our atmosphere, which extends from sea level to the highest mountain peaks (the troposphere), is where most meteorological phenomena occur since it contains the most water vapor of any layer. Above that is the stratosphere, which contains the ozone layer that shields the surface from potentially harmful ultraviolet radiation.

Next is the mesosphere, which is very thin and cold but still dense enough that meteors will burn up as they pass through it. The thermosphere is next, where temperatures increase again with altitude (due to Solar heating).The uppermost layer is the exosphere, which is too thin for any meteorological phenomena to occur. However, the Aurora Borealis and Aurora Australis sometimes occur in the lower part of the exosphere, overlapping into the thermosphere.

For the sake of their study, the international team examined the exoplanet known as WASP-189b, a Hot Jupiter located 322 light-years from Earth. This planet was discovered in 2018 using the Wide-Angle Search for Planets (WASP) consortium, while extensive follow-up observations were conducted in 2020 using the ESAs CHaracterising ExOPlanets Satellite (CHEOPS). These revealed a planet about twice the radius of Jupiter that orbits its host star 20 times closer than Earth orbits the Sun leading to daytime temperatures of 3,200 C (5,790 F).

Using more recent observations with the High Accuracy Radial velocity Planet Searcher (HARPS), a spectrograph integrated with the 3.6-meter telescope at the ESOs La Silla Observatory, the team was able to examine the atmosphere of this Hot Jupiter for the first time. These spectral observations revealed an atmosphere with the chemical fingerprints of iron, chromium, vanadium, magnesium, and manganese.

As Lund doctoral student Bibiana Prinoth (who was the lead author on the study) explained in a University of Bern press release:

We measured the light coming from the planets host star and passing through the planets atmosphere. The gases in its atmosphere absorb some of the starlight, similar to Ozone absorbing some of the sunlight in Earths atmosphere, and thereby leave their characteristic fingerprint. With the help of HARPS, we were able to identify the corresponding substances.

In addition to the previously-mentioned minerals, the team was interested to find traces of titanium oxide gas. This substance has a melting point of 1,843 C (3350 F) and is very scarce on Earth, where it is typically used as a pigment known as titanium white. Because of its particular properties, this gas may play an important role in the atmosphere of WASP-180b similar to how ozone played an important role in the evolution of Earths atmosphere.

Like ozone, Titanium oxide absorbs short-wave electromagnetic radiation, including ultraviolet light. Therefore, the detection of this compound could indicate that there is a layer in WASP-189 bs atmosphere that interacts with stellar radiation the same way the Earths Ozone Layer does. Already, researchers have found hints of this and other layers on the ultra-hot Jupiter-like planet. As Prinoth explains:

In our analysis, we saw that the fingerprints of the different gases were slightly altered compared to our expectation. We believe that strong winds and other processes could generate these alterations. And because the fingerprints of different gases were altered in different ways, we think that this indicates that they exist in different layers similarly to how the fingerprints of water vapour and ozone on Earth would appear differently altered from a distance, because they mostly occur in different atmospheric layers.

These results may change how astronomers investigate exoplanets. In the past, astronomers tended to assume that the atmosphere of exoplanets existed as uniform layers and tried to characterize them as such. But these latest results demonstrate that even the atmospheres of extreme planets like ultra-Hot Jupiters have complex three-dimensional structures. AS co-author Kevin Heng, a professor of astrophysics at the University of Bern and a member of the NCCR PlanetS, concludes:

We are convinced that to be able to fully understand these and other types of planets including ones more similar to Earth, we need to appreciate the three-dimensional nature of their atmospheres. This requires innovations in data analysis techniques, computer modelling and fundamental atmospheric theory.

Further Reading: Bern University, Nature Astronomy

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Astronomers Measure the Layers of an Exoplanet's Atmosphere - Universe Today

Bill Wren remembers exactly where he was when he was first called the Angel of Darkness.

He doesn't remember the year, but it was at a Texas Star Party, an annual gathering of 500 or so amateur astronomers held at the Prude Ranch in Fort Davis, Texas. Wren, a longtime advocate for the dark skies movement against light pollution as a staffer at UT's McDonald Observatory, was well known by that point, so a Texas Star Party attendee introduced him to a crowd with a new heavy metal-sounding nickname.

"It got a real nice laugh, and it got repeated," Wren says. "The media picked it up."

Wren is good-natured talking about the stark sobriquet even though if it's not his favorite. But if it gets people talking about the necessary steps to keep the night sky dark and the stars bright, he'll make the sacrifice.

"I'm willing to go along with just about anything, but I don't care for the moniker very much. I can do without it," Wren laughs. "Whatever works, you know?"

Earlier this week, Wren retired from the McDonald Observatory, where he made dark skies education and advocacy his work for 32 years.

"The skies over McDonald Observatory are among the darkest of any professional observatory in the United States, in no small measure thanks to Bill Wren," Taft Armandroff, director of McDonald Observatory, said in a statement upon Wren's retirement.

Wren says it was time for him to pack it in, to give someone else a chance to take the baton and run with it. "Life is short. I was past due. The pandemic made things a little less fun, working from home all the time," he says.

That home was university housing at the observatory. The University of Texas at Austin, which operates the McDonald Observatory, chose West Texas' Davis Mountains for its site in 1933 because its skies are some of the darkest in the United States. Since then, light pollution has worsened, especially with drilling rigs cropping up in West Texas during oil booms. Every time that happens, bright lights shine into the night skies, which is detrimental to both the enjoyment of the cosmic view and the scientific work conducted by astronomers at the McDonald Observatory.

USA, Texas, Fort Davis, McDonald Observatory. Houses 430 inch Hobby-Eberly Telescope. Elevation 6791 feet.

A self-taught astronomer, Wren grew up in the hills of Missouri, where, he says, "the starry sky was splendid, almost like wallpaper." He moved to Houston at 15, and noticed that the sky looked different in the city after dusk. On a hunch, he drove out on 290 toward Hempstead. He was awestruck by the stars in the dark night sky.

"Wow, you know, you couldn't see that when I looked at yesterday," Wren remembers thinking. "And it's certainly gotten a lot worse."

That realization led to a lifelong interest in amateur astronomy, beginning with spotting Saturn's rings and Jupiter's moons from his backyard. He eventually bought a larger telescope and started traveling more with his Peterson Field Guide,learning the night sky over the course of a few years. While working at a runaway shelter in Austin and helping a state agency start its suicide hotline, he tutored astronomy students at UT Austin using his self-taught knowledge. He met Frank Bash, UT astronomy professor and the director of the McDonald Observatory, who was impressed with Wren and let him know that the visitor's center had a job opening.

"Thirty days later I pulled the plug on my counseling career in Austin and moved to West Texas," Wren says. "March 1, 1990 was just in time for spring break. It was baptism by fire."

During Wren's second month in Fort Davis, he was encouraged to attend a meeting of the International Dark Sky Association at the University of Arizona campus. He learned that areas could be well-lit without polluting the sky, that people were wasting light and ruining beautiful sights and complicating research for astronomers.

"I wouldn't call it a born-again experience because it's almost like being evangelized," Wren says. "It was just like wow, this is I need to help spread the word on this."

So that's what he did.

The summer Milky Way rises over the McDonald Observatory near Fort Davis, Texas.

In addition to hosting Star Parties and giving tours, Wren gave talks on dark skies for years. It was around 2011, during the oil and gas boom in the Permian Basin, he realized he needed to work directly with companies to keep the skies dark. It wasn't just the drilling sites, but from the adjacent commerce hotels, new housing, chain stores that comes with oil exploration. He remembers giving a presentation to San Antonio-based Pioneer Energy Services, whose president owned a ranch outside Marathon.

"He was waxing poetically about seeing the Milky Way horizon-to-horizon," Wren says. "He said, 'Yes, this is worth protecting, here's our fleet of drilling rigs. See what you can do with the lighting."

Around that time Wren stopped most of his other work at the observatory to focus on dark skies full time. He worked with many oil and gas companies to alter their lighting systems to reduce light pollution, he says, without much pushback at all. In fact, in most cases the sites became safer and with higher visibility and reduced glare, a true win-win for each side.

"And they do recognize the value in the night sky," Wren says. "Many of them do ... well, probably many of them don't. But there are people that get it."

Though light pollution can be reversed, dark skies are disappearing around the country as fewer locations with high visibility remain truly remote. Even though Wren is retiring, he is still staying active in the dark skies community from his new home in Cloudcroft, New Mexico.

"The places where people can go to see an actually dark night sky are rapidly shrinking and becoming fewer and farther between," Wren says. "And it's becoming the case that McDonald Observatory in particular, but the Big Bend region in general, is being recognized as a dark sky destination, a place where people can take in the night sky something with which most of us have lost track of the wonder, the splendor of it all. We're trying to get people to buy into preserving the night skies in far West Texas."

Wren says the best way for people to get the picture is to get a visual demonstration. He says that once you see the effects of light pollution on dark skies, you can't unsee it.

"Being able to do a demonstration or being able to point it out to someone so they can see it with their own eyes can be a very powerful, life altering thing," Wren says. "For some pool souls, it'll be cursing my name til the day they die."

Such is the blessing and the curse of the Angel of Darkness.

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They called him the Angel of Darkness. But this astronomer just wanted to keep West Texas skies pure. - mySA

A team of astronomy researchers has discovered a surprising fact from the first couple of billion years of the universe: there were at least some large groups of galaxies that were already burning out at the time, contrary to the general pattern of galaxies having vigorous star formation then.

The massive grouping of at least 38 young galaxies that was discovered, called protocluster MAGAZ3NE J0959, is about 11.8 billion light-years away from Earth, and was found using the W. M. Keck Observatory in Hawaii. At the center of MAGAZ3NE J0959 is an ultra-massive galaxy with more than 200 billion suns.

The discovery of this protocluster with a population dominated by ultra-massive galaxies with halted star-formation activity was surprising, said Danilo Marchesini, a Tufts professor of astronomy who was part of the research team. It shows that even in the early universe there was already a great range of diversity in terms of the properties of galaxies.

We were not expecting this, and this finding raises new exciting questions, said Marchesini, who was joined on the project by Tufts postdoctoral researcher Marianna Annunziatella.

One issue is if the censuses of distant protoclusters are biased or incomplete, he said. The fact that previously reported protoclusters at this epoch were found to contain mostly star-forming galaxies may be evidence that our view of dense environments in the early universe is at least incomplete, or most likely biased, as finding distant quiescent galaxies is much harder than finding actively star-forming galaxies.

The research team, led by University of California at Riverside astronomers Ian McConachie and Gillian Wilson, reported their findings in the Astrophysical Journal. In marked contrast to protoclusters previously reported at this epoch which have been found to predominantly contain star-forming members, MAGAZ3NE J0959 was found to have an elevated fraction of quiescent galaxies, the research team wrote. This suggests that protoclusters exist in a diversity of evolutionary states in the early Universe.

Looking ahead, the researchers note in the paper that future ground and space telescopes with the capability to survey significantly wider areas, such as the James Webb Space Telescope . . . will undoubtedly facilitate the discovery of larger samples, allowing better insight into the uniqueness of MAGAZ3NE J0959, and helping to propel our understanding of the formation of UMGs [ultra-massive galaxies] and protoclusters into the even earlier Universe.

Taylor McNeil can be reached at taylor.mcneil@tufts.edu.

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Astronomers Find Burned Out Galaxies in Ancient Universe - Tufts Now

Stochastic Processes and Dual Pairs of Operators

Abstract. A new harmonic analysis for Krein-Feller operators is presented. We first show that a Krein-Feller operator is associated to pairs of measures assumed positive, sigma-finite, and non-atomic. Our approach to the problem is via dual pairs of operators, referring to the corresponding pairs of L^2 Hilbert spaces.The operator pairs used for our Krein-Feller analysis consist of two specific densely defined (unbounded) operators, each one contained in the adjoint of the other. We show how this approach yields a rigorous analysis of the corresponding Krein-Feller operators as closable quadratic forms. For given measures, including the case of fractal measures, we compute the associated diffusion, Markov processes, semigroups, Dirichlet forms, and generalized heat equations. Key tools for our analysis are the use of associated reproducing kernel Hilbert spaces (RKHSs), time-change, and Gaussian fields.

ZOOM ID:965 4759 0309

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Operator Theory Seminar - Professor Palle Jorgensen; Univ of Iowa | Physics and Astronomy | The University of Iowa - Iowa Now

Completeness and complex probabilities in descrete systems

Abstract: I discuss a general real-time path integral treatment of discrete systems motivated by Jorgensen and Nathanson's treatment of real time path integrals based on complex probabilities. For imaginary times in the continuum theory there is a path measure that can be alternatively considered as a probability measure; while for real time there is no countably additive measure on the cylinder sets of paths, the probability interpretation survives if the notion of probability is properly extended to complex probabilities. In the discrete case the complex probability arises from the completeness relation, there are no Fresnel integrals, and the space of paths are cylinder sets of paths that take on discrete values of complementary pairs of observables at different time slices. The cylinder sets of discrete paths are in 1-1 correspondence with ordered sequences of transition amplitudes involving complementary pairs of operators. I will discuss a trivial application to quantum field theory.

ZOOM ID:956 5927 4425

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Math Physics Seminar - Professor Wayne Polyzou | Physics and Astronomy | The University of Iowa - Iowa Now