Category Archives: Astronomy

G C ANUPAMA, president, Astronomical Society of India (ASI), Saturday said India needs more observational facilities and telescopes in order to do competitive research at par with the global community.

She was delivering the presidential address at the 40th ASI meet hosted at IIT-Roorkee and jointly organised with Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital.

India is lagging in observational facilities, thus making us dependent for data on other (global) facilities. This is not a happy situation. India needs to improve the observational facilities and have access to multi-wavelength and multi-messenger facilities, said Anupama. The Giant Metrewave Radio Telescope in Pune, she said, remains among the few world-class facilities available in India. Apart from some telescope facilities working between the 1 metre to 4 metre class, India otherwise does not have telescopes in the optical and infra-red spectra that function in ranges between the 8 metre to 10 metre class for doing competitive science, she said.

According to Anupama, Astronomy, over the recent decades, has grown with a lot of synergy present now in doing science. With Indias participation in the mega science projects like the Thirty Metre Telescope, Laser Interferometer Gravitational Wave Observatory and the Square Kilometre Array projects, a stronger astronomy community was required.

India with a unique longitudinal positioning and places like Ladakh hold promising locations to set up suitable telescopes in future, proposals for which are under consideration, she said. We need to expand also to the submillimetre region the area of star formation. There is a need to upgrade and network the existing telescope facilities with the global ones, especially for studying transient objects, she said.Earlier in the day, the ASI 2022 was formally inaugurated by Professor K Vijay Raghavan, Principal Scientific Adviser to the Government of India. I urge the Indian astronomy community to plan forward-looking and futuristic research plans which will help India make significant contribution in global mega science projects, he said.

In his virtual address, he further elaborated on artificial intelligence (AI) and machine learning (ML) and their growing uses.

Anupama talked about the current areas of research and mentioned that Astronomy was among the top areas included in the Mega Science Vision Document 2035, an effort led by the office of Principal Scientific Advisor. This document will be a roadmap for deciding future course of research covering nuclear science, high energy physics, astronomy and astrophysics, accelerator-based science and technology and climate research, ecology and environment.

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India needs more world-class telescopes to do competitive research in Astronomy: Anupama - The Indian Express

April 8 Star Gaze with Oakland Astronomy Club in Oakland Twp.

April 8 Star Gaze with Oakland Astronomy Club in Oakland Twp.

Share safe telescopic views of the Winter night sky with the Oakland Astronomy Club. See details of lunar craters and the colorful gases of the star nursery in Orion. Find the Big Dipper and Leo the Lion and enjoy the colorful stars of the Winter sky before they disappear for the season!

April 8th, 8-9:30 for adults to teens, at Marsh View Park,3100 E Clarkston Rd, Oakland, MI 48363. Register online at: https://oaklandtownship.recdesk.com/Community/Program/Detail?programId=677

April 9th, 8-9:30 for star gazers of all ages, at Independence Oaks County Park, 501 Sashabaw Rd., Clarkston, MI 48348. Register via phone with Oakland County Parks during weekday business hours at248-858-0916.

More info: http://oaklandastronomy.net/event.html

For more things to do, visit the Oakland County Times Event Page! To submit event info email editor@oc115.com .

Thank you to Jim Shaffer & Associates Realtors for sponsoring this section!

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April 8 Star Gaze with Oakland Astronomy Club in Oakland Twp. Oakland County Times - Oakland County Times

Basic structure of our home galaxy, edge-on view. The new results from ESA's Gaia mission provide for a reconstruction of the history of the Milky Way, in particular of the evolution of the so-called thick disc. (Stefan Payne-Wardenaar / MPIA via ESA)

Scientists have discovered that parts of the Milky Way galaxy are actually older than previously thought at least by two billion years.

Data collected by the European Space Agencys (ESA) Gaia mission was analyzed by astronomers from the Max-Planck Institute for Astronomy in Heidelberg, Germany, and compared to earlier datasets from Gaias observation of the motion of stars in the outskirts of our galaxy, also known as the anticentre, in 2020.

In addition, astronomers received data from Chinas Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) for roughly 250,000 stars to derive their ages, according to an agency news release.

Combining this information, astronomers were able to determine that stars within the "thick disc" part of our galaxy began forming 13 billion years ago, around 2 billion years earlier than expected, and just 0.8 billion years after the Big Bang, according to the ESA.

So, our beautiful galaxy is made up of billions of components, but to keep things simple, well narrow it down to the disc and the halo.

If one were to hypothetically look at our galaxy and it laid flat, you would be able to see a bulge in the center of the disc, which is essentially the center of our galaxy.

Surrounding that disc is the stellar halo, which is the outermost part of our galaxy and was originally believed to be the oldest part of the Milky Way, the ESA said.

The halo has a radius of about 100,000 light-years and contains isolated stars as well as many globular clusters, which are basically clusters of millions of stars packed into one area.

The galactic disc is made up of both thick and thin discs. The thin disc, which is about 700 light-years high in comparison to the galactic disc, contains most of the stars we humans can see. Its often photographed as a misty streak across the night sky and dotted with stars.

The thick disc, which is about 3,000 light-years high, contains fewer stars but this is the area where astronomers were able to find their surprising discovery, thanks to Gaia, according to the ESA.

An artists impression of our Milky Way galaxy, a roughly 13 billon-year-old barred spiral galaxy that is home to a few hundred billion stars. (NASA/JPL-Caltech; right: ESA; layout: ESA/ATG medialab)

Determining a stars age is one of the most difficult things to decipher, according to the ESA.

"It cannot be measured directly but must be inferred by comparing a stars characteristics with computer models of stellar evolution. The compositional data helps with this," according to the ESA.

Astronomers must take into account the matter of which a star is made in its early stages which includes hydrogen and helium. Once a star is born, it will continue to develop and create metals within itself. These metals are expelled out into space as a star grows older, according to the ESA.

So, to make a very complicated method easy to understand: The fewer metals a star has, the older it is.

"Together, the brightness and metallicity allow astronomers to extract the stars age from the computer models," the ESA said.

The Milky Way was formed in two phases, according to the ESA.

The first phase was the Big Bang which happened around 0.8 billion years ago, scientists believe.

The aforementioned "thick disk" began to form at this time. Astronomers also believe other parts of the galaxy, such as the inner parts of the stellar halo which basically encircles the entirety of the Milky Way galaxy, began to form as well.

Then, the Gaia-Sausage-Enceladus, which was a dwarf galaxy hurtling through space, collided with the Milky Way and rapidly accelerated the formation of our galaxy, according to Carnegie Mellon University.

This collision gave birth to millions of stars, according to the ESA.

During the second phase of the galaxys formation, a thinner disc developed as all of the space matter began to form together and thats when Earths sun and subsequent planets were formed.

This story was reported out of Los Angeles.

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Parts of Milky Way are older than expected, astronomers say - FOX 6 Milwaukee

Growing up, Jesse Stout remembers learning about astronomy from his dad.

"When I was younger my father used to take us out camping and that was probably the first time I was introduced to astronomy," he said.

"We used to look up at the stars and my father used to point out things I'm not too sure how accurate he was."

But a life-changing workplace accident in 2018 saw him rethink how he saw himself, and rediscover an old interest.

"A lot of my hobbies before my accident were very, very active, so camping, going to the beach or surfing," he said.

"The ASV has allowed me to explore my new hobby and be positive about a new element in my life I think that's a very, very hard thing to express when you've got a disability."

Late last year, as he recovered from a second surgery on his back, Jesse's partner and family decided to pool their money to buy him a telescope.

Excited to try it out, Jesse soon discovered having to manoeuvre himself around the equipment came with a very painful drawback, that could leave him in pain for days afterwards.

Looking around for groups to join, he found the Astronomical Society of Victoria's (ASV) Pathways to the Planets project, trying to raise funds to make their sites and equipment more accessible for people with varying levels of mobility.

With around 12 per cent of its members having some sort of disability, ASV Vice president Mark Iscaro said it was stories like Jesse's that inspired them.

"The sky belongs to everyone," he said.

"If there are people who've got sight issues, they should still be able to feel the night sky, whether that's through 3D-printed star maps, and those with mobility issues shouldn't be prevented from coming up and seeing the stars."

Now, in the year of their 100th anniversary, the society has opened an all-abilities accessible observatory at the Leon Mow dark sky site near Heathcote, north of Melbourne, with features such as better-lit and widened pathways, a motorised entry gate and accommodation for those staying overnight.

There are also plans to build remote-controlled astrophotography observatories for people who can't physically travel to the site, or use an eyepiece.

The main attraction is a specially designed telescope, altered to make the eyepiece the axis so it stays at the perfect height for a viewer sitting down.

ASV President Chris Rudge said traditional astronomical equipment wasn't always easy for everyone to use.

"Unfortunately, to use those large telescopes you have to go up a ladder, but this new telescope we've specially built so that you can sit down and look at the night sky," he said.

"We have many older members these days, including myself, who may be mobility-limited, they can just sit down and enjoy the night sky at their leisure."

The telescope is the second in Victoria, with the first being in the regional town of Ballarat.

But the ASV is hoping their larger member base and more widely accessible facilities will attract more keen astronomers in the future.

Jesse was just looking forward to enjoying his hobby pain-free.

"I'll be able to use the telescope and I'll be able to look at the stars and not have to worry about the next day that I'm going to be bedridden because of the pain from bending down or moving around or adjusting my body slightly," he said.

And it has reminded him of what he loves about looking up at the skies.

"There's a huge element of mystery behind astronomy," he said.

"Being able to look up into the sky and realising you're finding something new each time you look and the fact that a telescope can bring you even closer to finding something."

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A new all-abilities accessible observatory in Heathcote is opening up new worlds for Victorians - ABC News

The Sun is literally the closest star to us in the entire Universe, but theres a lot about it thats still pretty mysterious.

For example, nearly 150 years ago, the astronomer Angelo Secchi first observed narrow, towering fingers of material stretching vertically away from the Sun. Called spicules, these can grow to a height of 12,000 kilometers nearly the diameter of the Earth but tend to be only 1/10th that wide. They grow in a matter of minutes, shooting upwards at tens of thousands of kilometers per hour, then collapse back down.

There are millions of spicules on the Sun at any given moment, and they look like grass or shag carpeting. Time-lapse video of them is entrancing and eerie:

And while theyre known to be associated with strong magnetic fields typical of phenomena on the Sun even after all this time its not clear what causes them. Paper after paper has been published over the years, with varying degrees of success in explaining these weird features.

A few years ago, a study showed that they may be due to the way the magnetic field interacts with both electrically neutral and charged particles on the Suns surface. However, a different team of solar astronomers wondered if there might be a more fundamental piece of physics going on with them. They noticed how fluids can dance when vibrated by the sound waves from a speaker heres a good video of that and thought there might be a connection. When the surface of a fluid is vibrated you can get neat patterns in it as waves get pumped up by them, but as the frequency gets higher theres a critical frequency when the surface starts to create jets of water shooting up. This type of motion is called Faraday excitation or Faraday waves. Usually in water or other liquids the top of the jet breaks off into a droplet that then falls back to the surface.

This type of event is common in nature; in fact alligators use a low-frequency mating call that can cause it to happen in the water around them, shown in this video about 20 seconds in.

The Suns surface is a plasma, mostly hydrogen thats so hot the atoms have lost an electron, and is dense enough to act like a fluid. Also, there are plenty of sources of vibrations in the solar surface. Deep inside the Sun theres a layer where extremely hot material rises buoyantly, and when it gets to the surface it cools and falls back down. This is called convection, and there are many towering convective conveyor belts transporting material up and down in the Sun. This causes a continuous rumble on the surface at a frequency that could excite Faraday waves.

The new research [link to paper] first shows that the physics of Faraday waves in the Sun and in a fluid dancing on a speaker are similar. They then experimented in the lab with various fluids to see if they could mimic spicules. They found that a diluted mixture of a polymer (specifically polyethylene oxide) when placed over a speaker can create jets very similar to spicules, and when diluted at the right amount the droplet creation is suppressed as well. Spicules dont make droplets, so given that the math is similar to describe both effects, there could be some physical similarities.

They then turned to software that simulates the behavior of the solar plasma. Using the known physics of how it behaves, the code can be tweaked to see if certain behaviors can be reproduced. Without any real detailed inputs just using the vibrations of the solar surface created from sound waves of certain harmonic frequencies their code reproduced spicule-like structures. Thats encouraging! They also found the driving frequency doesnt need to be harmonic (that is, sound waves of evenly divisible frequencies, like say 440 and 220 and 110 Hertz), but can be quasi-periodic; mostly periodic but with some randomness thrown in. Thats good too, as the Suns surface is a cacophony of different frequencies that dont always create harmonic chords.

When they added a simple vertical magnetic field to their code they found they got even more spicule-like behavior, with about the right heights and widths. The speed of growth was similar, too. The magnetic field introduces an anisotropy, a non-symmetric nature to the surface that helps squeeze the plasma into narrow towers. This is similar for the need of the polymeric fluid to be diluted; that also is an anisotropy that helps the jets form.

The overall conclusion is that they found a more fundamental reason spicules might be produced on the Sun without the need for lots of special circumstances. This doesnt mean earlier research was wrong, necessarily, but it can be nice to reach for more basic physics sometimes to see what it contributes, and then add layers to it.

And, like the earlier attempts to explain spicules, its hard to know if this is the right answer. Just because the experiments and code make something that looks like spicules doesnt mean thats whats going on.

As I like to point out, this is the nature of science. We usually wind up with lots of ideas to explain a phenomenon, and it can take a while to weed out which ones are actually involved and which arent. The Sun is a nightmare of complexity, and a lot of its behavior is incredibly difficult to understand. But we now have observatories like Hinode and Solar Dynamics Observatory and the Inouye Solar Telescope that can see the Sun in high resolution and at wavelengths of light our eyes cant see, and all these observations help the theorists figure out whats what.

As time goes on, well understand the Sun better and better. That too is how science works.

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Bad Astronomy | Spicules on the Sun may be due to Faraday waves | SYFY WIRE - Syfy

There are thousands of near-Earth asteroids in the inner solar system, as depicted in this graphic. Some known and some unknown. Another asteroid discovered by the same astronomer to discover 2022 EB5 in early March made a close pass with Earth in the early hours of March 25, 2022. Image via NASA/ JPL-Caltech/ Wikimedia Commons.Another asteroid whizzes past Earth overnight

Overnight on March 24-25, 2022, another small asteroid raced toward Earth, unseen until hours before its closest approach. Hungarian astronomer Krisztin Srneczky, same astronomer who first spotted asteroid 2022 EB5 earlier this month hours before it hit Earth near Iceland, found this new asteroid, too. He caught it just hours before it sped by Earth. This asteroid is labeled Sar2594. Its close encounter with Earth came at 8:10 UTC or 3:10 a.m. CDT.

This time, instead of a collision, the space rock slipped through Earths shadow.

It passed at a distance of about 5,400 miles (8,700 km). Thats in contrast to the moons distance of 238,900 miles (384,000 km).

Sar2594 is categorized as a Near-Earth Object, or NEO. It raced by at about 40,265 miles an hour (18 km/s).

Sar2594 now has an official designation: 2022 FD1. Srneczky says the asteroid is about 2-4 meters in size. This could put it in the running for the smallest asteroid known. The current record holder is 2015 TC25, which is approximately 6 feet or 2 meters in diameter.

The asteroids flyby of Earth changed its course. Srneczky and Tony Dunn share charts and simulations of 2022 FD1s inclination:

Bottom line: Another asteroid whizzes past Earth hours after discovery. The asteroid, Sar2594, was discovered by the same astronomer, Krisztin Srneczky, who discovered 2022 EB5, which impacted near Iceland earlier this month.

Kelly Kizer Whitt has been a science writer specializing in astronomy for more than two decades. She began her career at Astronomy Magazine, and she has made regular contributions to AstronomyToday and the Sierra Club, among other outlets. Her childrens picture book, Solar System Forecast, was published in 2012. She has also written a young adult dystopian novel titled A Different Sky. When she is not reading or writing about astronomy and staring up at the stars, she enjoys traveling to the national parks, creating crossword puzzles, running, tennis, and paddleboarding. Kelly lives with her family in Wisconsin.

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Whoa! Another asteroid whizzes past Earth hours after discovery - EarthSky

image:An artistic impression of the high-frequency retrograde (HFR) vorticity waves. These waves appear as swirling motions near the equator of the Sun. The rotation in the north is always anti-symmetric to the rotation in the southern hemisphere. These mysterious waves move in the opposite direction to the sun's rotation, which is to the right, three times faster then what is allowed by hydrodynamics alone. view more

Credit: NYU Abu Dhabi

Abu Dhabi, UAE: Researchers from NYU Abu Dhabis (NYUAD) Center for Space Science have discovered a new set of waves in the Sun that, unexpectedly, appear to travel much faster than predicted by theory.

In the study, Discovery of high-frequency-retrograde vorticity waves in the Sun, published in the journal Nature Astronomy, the researchers led by Research Associate Chris S. Hanson -- detailed how they analyzed 25 years of space and ground-based data to detect these waves. The high-frequency retrograde (HFR) waves - which move in the opposite direction of the Suns rotation - appear as a pattern of vortices (swirling motions) on the surface of the Sun and move at three times the speed established by current theory.

The interior of the Sun and stars cannot be imaged by conventional astronomy (e.g. optical, x-ray etc.), and scientists rely on interpreting the surface signatures of a variety of waves to image the interiors. These new HFR waves may yet be an important puzzle piece in our understanding of stars.

Complex interactions between other well known waves and magnetism, gravity or convection could drive the HFR waves at this speed. If the HFR waves could be attributed to any of these three processes, then the finding would have answered some open questions we still have about the Sun, said Hanson. However, these new waves dont appear to be a result of these processes, and thats exciting because it leads to a whole new set of questions.

This research was conducted within NYUADs Center for Space Science in collaboration with the Tata Institute of Fundamental Research (TIFR) and New York University, using NYUAD and TIFRs computational resources. By studying the Suns interior dynamics - through the use of waves - scientists can better appreciate the Sun's potential impact on the Earth and other planets in our solar system.

The very existence of HFR modes and their origin is a true mystery and may allude to exciting physics at play, said Shravan Hanasoge, a co-author of the paper. It has the potential to shed insight on the otherwise unobservable interior of the Sun.

Image caption: An artistic impression of the high-frequency retrograde (HFR) vorticity waves. These waves appear as swirling motions near the equator of the Sun. The rotation in the north is always anti-symmetric to the rotation in the southern hemisphere. These mysterious waves move in the opposite direction to the sun's rotation, which is to the right, three times faster then what is allowed by hydrodynamics alone.

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About NYU Abu Dhabi

http://www.nyuad.nyu.edu

NYU Abu Dhabi is the first comprehensive liberal arts and research campus in the Middle East to be operated abroad by a major American research university. NYU Abu Dhabi has integrated a highly selective undergraduate curriculum across the disciplines with a world center for advanced research and scholarship. The university enables its students in the sciences, engineering, social sciences, humanities, and arts to succeed in an increasingly interdependent world and advance cooperation and progress on humanitys shared challenges. NYU Abu Dhabis high-achieving students have come from over 115 countries and speak over 115 languages. Together, NYU's campuses in New York, Abu Dhabi, and Shanghai form the backbone of a unique global university, giving faculty and students opportunities to experience varied learning environments and immersion in other cultures at one or more of the numerous study-abroad sites NYU maintains on six continents.

Discovery of high-frequency-retrograde vorticity waves in the Sun

24-Mar-2022

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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NYU Abu Dhabi researchers discover a mysterious, new type of wave in the Sun whose speed defies explanation - EurekAlert

Dr. Amruta Jaodand;Division of Physics, Mathematics and Astronomy,California Institute of Technology

Transitional millisecond pulsars (tMSPs) switch between a low-mass X-ray binary (LMXB) and a radio millisecond pulsar (RMSP) state, establishing a firm evolutionary link between the two source classes. tMSPs provide a great avenue to study the low-level accretion processes that spin-up pulsars to millisecond periods. Systematic, multi-wavelength observational campaigns over the last decade have resulted in surprising finds such as: i) persistent, multi-year-long, low-level (Lx <10^34 ergs/s) accretion state with coherent pulsations; ii) extremely stable, bi-modal X-ray light curves; iii) radio outflows, and iv) uninterrupted pulsar spin down in the X-rays. In this unique state, we have now found the first known UV millisecond pulsar with a dedicated multi-wavelength campaign involving the Hubble space telescope. In my talk I will review observational understanding of tMSPs while highlighting key finds which reveal how these systems have altered our understanding of low level accretion and pulsed emission in neutron stars.

Biography:Dr. Amruta Jaodand is a postdoctoral reseacher in the NuSTAR group at Caltech's Division of Physics, Mathematics and Astronomy. Previously, she did her PhD at University of Amsterdam. She works on observational investigations of various neutron stars such as millisecond pulsars, magnetars, gravitational wave engines and X-ray binaries with a deeper expertise in transitional millisecond pulsars and multi-wavelength gravitational wave follow up. As a PI, she has won observational time and funding for ~30 proposals spanning observatories such as XMM, NuStar, Swift, Green Bank Telescope, ZTF and VLA etc. Another interest of hers is astroinformatics in the era of large scale datasets. To that effect she has worked for the past five years in bringing together EU and American astronomers through multiple conferences to probe machine learning and visualisation approaches.

22 MAR 2022: Physics and Astronomy Colloquium3:30pm, Online via ZoomZoom Link:https://uiowa.zoom.us/j/94392147007Meeting ID: 943 9214 7007, No passcode

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Physics & Astronomy Colloquium - Dr. Amruta Jaodand | Physics and Astronomy | The University of Iowa - The University of Iowa

An IDAS LPS-D2 filter suitable for two-inch push-fit telescope camera accessories with an M48 0.75 connection thread. The filter has male and female threads on either side, hence it is stackable with other filters and M48 adaptors. The LPS-D2 is also available in 52mm and Canon APS-C clip-filter formats. All images: Ade Ashford.At a glance

Type: light-pollution suppression filter for low-/high-pressure sodium vapour and LED lightsCoating technology: Ion-Gun Assisted Deposition (IGAD)Suitability: DSLR and astro camerasConnection thread: M48 0.75 (male and female on either side, hence stackable)Substrate thickness: 2.5mmDiameter of filter glass: 49mmPrice: 175 (M48 and 52mm); 185 (Canon APS-C clip filter)Manufacturer: ICAS Enterprises, JapanSupplier: rothervalleyoptics.co.uk

Light pollution is a regrettable fact of life for most of us. By night, the sky over our cities and towns even villages is increasingly awash with the glare of unnecessary or misdirected artificial light. This is not only a tremendous waste of energy, but it upsets nocturnal ecosystems and harms human health, disturbed sleep patterns and the disruption of natural circadian rhythms.

For almost three decades, Tokyo-based ICAS Enterprises IDAS Division has been responsible for manufacturing some of the worlds most respected interference filters for suppressing light pollution for astronomers. Their LPS-D1 filter made its debut in 1991 at a time when the main sources of artificial illumination in our towns and cities were low- and high-pressure sodium vapour and mercury vapour lamps. Fortunately for astronomers, both sodium (Na) and mercury (Hg) vapour lamps share a common characteristic: they typically emit light in specific and largely narrow wavelength bands of the spectrum so-called emission lines that can be removed by an interference filter.

The LPS-D1 was designed for one-shot CCD/CMOS colour cameras and DSLRs to eliminate the glow from low-pressure sodium and high-pressure mercury street lights, while substantially reducing the peak intensities of high-pressure sodium light emissions. Both the IDAS D1 and P2 filters pass the desirable spectral lines of hydrogen-beta, oxygen-III, hydrogen-alpha light from nebulae, plus diatomic carbon (C2, the so-called Swan bands) from comets. The LPS-P2 is virtually identical to the D1 except for a slightly greater red sensitivity encompassing sulphur-II emissions.

As many of us up and down the United Kingdom and around the world are now acutely aware, the nature of street lighting is rapidly changing. The mellow yellow glow of low-pressure sodium light is being replaced with the energy-efficient yet brilliant white glare of light-emitting diodes (LEDs). I never thought that I would lament the passing of sodium street lights, but at least their light was relatively easy to mitigate. White LEDs, on the other hand, emit what is largely a continuous spectrum across a swathe of wavelengths (or colours, if you prefer) which is far harder to filter out.

If you consult the accompanying graph that shows the spectral profile of a typical white LED in blue, you will see immediately that it emits its greatest intensity of light almost 98 per cent transmittance in a well-defined peak at a wavelength close to 463 nanometres (nm), which is 4.63 107 metres, or 0.000463mm. Thus, the peak emission of a typical white LED is actually in the violet end of the blue region of the visible spectrum, at wavelengths that research has shown disrupts human circadian rhythms by keeping our brains in an awake state.

After the initial peak intensity, the white LEDs transmittance rapidly drops to around nine per cent at a wavelength of about 486nm in the bluegreen part of the spectrum. Thereafter, the transmittance rises steeply to a secondary, broader peak intensity of 53 per cent at about 560nm in the yellow part of the visible spectrum before gradually tailing off to zero in the far-infrared. If we were to use a conventional IDAS LPS-D1 or P2 filter on a white LED, then its peak intensity and much of its broader secondary intensity would not be filtered out. Clearly, we need another type of interference filter.

I was able to obtain data for the LPS-D2 filter based on a laboratory analysis rather than just rely on the design specification. The accompanying graph is a plot of the filters transmission versus wavelength in yellow, superimposed with that of a typical white LED in cyan. Where the white LEDs light intrudes into the D2 filters transmission curve is shown in green. Furthermore, the graphic shows the emission spectra of desirable nebula light (vertical dashed green lines), plus residual sources of light pollution that we wish to remove or mitigate (vertical red dashed lines). At the top and bottom of the graphic we see a continuous spectrum showing the approximate colour that corresponds to a specific wavelength; V = violet, B = blue, G = green, and so on.

The IDAS LPS-D2 is clearly very effective at removing the initial and most intense transmission spike from a typical white LED centred around 463 nanometres. However, when we come to capturing the desirable emission spectra of nebulae and comets in the blue green part of the spectrum hydrogen-beta, oxygen-III and diatomic carbon the intrusion of the LEDs light rises from a transmission of nine per cent at the hydrogen-beta line to around 30 per cent at the Swan bands of diatomic carbon. Note that some high-pressure mercury light pollution at 436nm and 546nm will also be passed by the LPS-D2 filter. Similarly, the second transmission peak of the LPS-D2 encompasses some of the white LEDs secondary peak light at around 52 per cent transmittance, so your white balance will have some strong green dominance. Fortunately, low-pressure sodium light pollution is fully suppressed and by the hydrogen-alpha and sulphur-II emission lines the white LEDs transmission is down to just 18 and 13 per cent, respectively.

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Beating the LED streetlights: IDAS light-pollution suppression LPS-D2 filter Astronomy Now - Astronomy Now Online

A mysterious, repeating radio signal in the Milky Way that baffled astronomers could be an object so rare, only one other has ever been tentatively identified.

According to a paper by astrophysicist Jonathan Katz of Washington University at St. Louis, uploaded to preprint server arXiv, and yet to be peer-reviewed, the signal named GLEAM-X J162759.5523504.3 could be a white dwarf radio pulsar.

"Since the early days of pulsar astronomy there has been speculation that a rotating magnetic white dwarf might show pulsar-like activity," Katz wrote in his paper.

"The recently discovered periodic radio transient GLEAM-X J162759.5523504.3 is a candidate for the first true white dwarf pulsar. It has a period of 18.18 minutes (1091 s) and its pulses show low frequency (72215 MHz) emission with a brightness temperature 1016 K implying coherent emission. It has no binary companion with which to interact. It thus meets the criteria of a classical pulsar, although its period is hundreds of times longer than any of theirs."

When a star dies, there are a range of outcomes, once it has ejected its outer material and core, no longer supported by the outward pressure of fusion, it collapses under its own gravity.

If the precursor star is over around 30 times the mass of the Sun, the core collapses into a black hole.

A precursor star between eight and 30 times the mass of the Sun results in a neutron star, around 20 kilometers (12 miles) across and up to around 1.4 times the mass of the Sun.

The core of a precursor star less than eight times the mass of the Sun will collapse into a white dwarf, packing mass up to 1.5 times that of the Sun into a ball between the sizes of Earth and the Moon.

Pulsars are a subset of neutron stars. They're neutron stars that rotate insanely fast, and angled in such a way that beams of bright radio waves shooting from the magnetic poles sweep past Earth on every rotation on the scale of seconds down to milliseconds. (Here's what that sounds like transcribed into audio.)

Scientists have wondered if similar behavior might be observed in white dwarf stars, and in 2016, they seem to have come close,with a star called AR Scorpii. Locked in a binary system with a red dwarf star, AR Scorpii flashes on a timescale of minutes.

However, as Katz notes, its binary orbit is closer than those of neutron star pulsars in binary systems, and the periodic signal lacks coherence. This means that the physical processes that produces the signal might be very different from traditional radio pulsars.

This brings us back to GLEAM-X J162759.5523504.3, located roughly 4,000 light-years away from Earth. From January to March of 2018, data collected by the Murchison Widefield Array in the Australian desert showed it pulsing brightly for roughly 30 to 60 seconds, every 18.18 minutes one of the most luminous objects in the low-frequency radio sky.

It matched the profile of no known astronomical object, but the research team that discovered it thought it might be a hypothetical object known as an ultra-long-period magnetar. That's a neutron star with an extraordinarily powerful magnetic field, but the explanation still didn't quite fit.

"Nobody expected to directly detect one like this because we didn't expect them to be so bright," astrophysicist Natasha Hurley-Walker of the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Australia explained at the time. "Somehow it's converting magnetic energy to radio waves much more effectively than anything we've seen before."

A pulsar was considered as a possibility, but there are two major problems: the first is that long rotation period, and the second is that the pulses were too bright for a neutron star pulsar. Both these problems, Katz lays out, are resolved if the object is a white dwarf.

If this is the case, it would be the first white dwarf discovered that shares the physics and radiation mechanism of traditional radio pulsars. This means that GLEAM-X J162759.5523504.3 could be a promising target for optical observations; although white dwarfs are very dim, and we might not be able to pick up any visible light at its distance. Nevertheless, given the possibility, it's worth a shot.

And astronomers could also examine other white dwarfs, to see if they match any of the properties of GLEAM-X J162759.5523504.3.

"If it were bright enough, optical observations could also determine its magnetic field, spectroscopically or polarimetrically," Katz explained.

"The fast-rotating, strongly magnetized, white dwarves would be promising targets for low frequency radio observations to determine if any of them are white dwarf pulsars."

The paper has been uploaded to preprint server arXiv.

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Mysterious Signal Coming From Our Galaxy Could Be One of The Rarest Known Objects - ScienceAlert