Category Archives: Astronomy

Where the heck is the neutron star that should be in the middle of the debris from Supernova 1987A?

It's one of the bigger mysteries of modern astronomical times. On the night of February 23/24, 1987 (essentially 34 years ago today, so happy anniversary!) the light from an exploding star reached Earth. Dubbed Supernova 1987A, it came from the Large Magellanic Cloud, a satellite galaxy of the Milky Way just 160,000 light years away. That's close enough that the supernova was visible to the naked eye, and it became one of the most well studied astronomical objects in history*.

The star that blew up was massive, probably about 20 times the mass of the Sun. When a star like that reaches the end of its life it blows a series of powerful winds of gas that surround it. Some tens of thousands of years later the core of the star collapses, setting up an immense explosion that blasts away its outer layers: Supernova.

The collapsing core of a massive star can become either a black hole or an incredibly dense neutron star. In this case, it should've formed the latter.

Newborn neutron stars have powerful magnetic fields and spin rapidly. They blast out beams of high-energy radiation like sweep around like a lighthouse beam, which we see when they pass over us. We get blips of radiation like pulses, so these young neutron stars are called pulsars. They're usually pretty obvious (like a baby screaming on an airplane; the source isn't too tough to spot). But in this case, despite intense searches for over three decades, no neutron star has been found.

However, in the past couple of years evidence is starting to come in. A blob of radio emission was seen recently that could be from the baby neutron star, but it's not 100% certain. Now, astronomers have gone over some archived X-ray observations taken from 2012 2014 and find that they too point toward the X-rays coming from the neutron star.

X-rays are a form of light, like the light we see but with far higher energies. It takes powerful events to create them. In a young supernova they could be from the blast wave generated by the expanding debris from the explosion slamming into the gas outside it, or they could be from a seriously strong wave of particles, called the pulsar wind nebula, accelerated by the neutron star's ridiculously fierce magnetic field.

The astronomers looked at the X-ray observations from two space-based observatories, the Chandra X-ray Observatory and NuSTAR. Chandra sees relatively low energy X-rays, and NuSTAR much higher energy ones.

What they found is that the X-ray spectrum the brightness of the X-rays versus their energy from the two observatories combined showed that the low-energy X-rays were consistent with the blast wave idea. But if that were the case they'd expect very few high-energy X-rays. However the spectrum clearly shows more high-energy ones than expected.

That leans more toward the idea these X-rays are coming from the pulsar wind, which emits far more high-energy X-rays. The spectrum by itself isn't conclusive. However, we also have a grasp of what's going on physically inside the supernova, and it's much easier to match the spectrum to the physics of a pulsar wind than a blast wave. That's also not conclusive, but it gives a lot more credence to the existence of a neutron star in the middle of all that junk.

There's a way to know better too. All the dense material surrounding the center of the explosion is blocking our view somewhat. Over time that material expands and gets less dense. Like a fog clearing, that should allow more high-energy X-rays through. If we see the higher energy X-rays get brighter, that would strongly favor the pulsar wind model. If instead they get fainter that favors the blast wave idea (which should fade more rapidly over time). Hopefully future NuSTAR observations can settle this question.

We see neutron star pulsars in the centers of many supernova remnants (like the famous Crab Nebula pulsar, or the one in the Vela supernova remnant), and they are an important factor in the shaping and evolution of the rapidly expanding debris from the explosion. The gas around Supernova 1987A, blown by the star before it died, is a bit bizarre, shaped like a huge hourglass with a dense ring in the middle. The actual stellar debris is in the middle of all that, and will slam into this gas over the next few centuries.

If there's a pulsar in there, its vast stores of energy will accelerate that material in the collision like hitting the gas in a car. If we want to understand how this interaction will occur and oh my we do, since it's the closest such supernova in centuries then we need to know if there's a neutron star in the middle of all that and what's its doing to add to the chaos. Hopefully soon we'll find out.

*Three years later the newly launched Hubble Space Telescope made SN1987A one of its very first targets; I used those and subsequent observations to get my PhD in astronomy, so this topic is close to me.

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Is there an angry baby neutron star in the middle of Supernova 1987A? - SYFY WIRE

This is an automated machine translation of an article published by Business Insider in a different language. Machine translations can generate errors or inaccuracies; we will continue the work to improve these translations. You can find the original version here.

Astronomy wants to become a field open to the whole of society, not only to observe stars and planets but also to prevent the destruction of the planet itself due to an unplanned impact.

This is the goal of Unistellar Optics, the company that has developed the eVscope home telescope, so that, from the comfort of one's home, anyone can look up at the vast universe that looms over humanity.

In a compelling tone, the company launched a challenge to observe the trajectory of Apophis on February 21, the day it was hidden behind a star, so it could be observed; moreover, it will pass dangerously close to the Earth and the Moon by the year 2029, 2036 and 2068, the latter being the one with the highest risk of impact.

To do so, they launched the challenge of observing the "infamous" Asteroid 99942 Apophis. They wonder if it would be capable of destroying orbital satellites or directly impacting the Earth's atmosphere.

Thus, Apophis has been classified as a Potentially Hazardous Asteroid -PHA-, since, in 2029, it is expected to pass 31,860 kilometers away from the Earth's surface.

By 2029, Apophis' orbit is expected to change due to its approach to Earth and the Moon.

These predictions have been joined by the latest ones made by NASA's CNEOS center, in charge of cataloging objects at risk of impact, which has observed how this has decreased thanks to the so-called Yarkovsky effect, by which the orbit of a small object in the Solar System is modified due to the absorption of solar radiation.

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"One of the great mysteries about Apophis is how its orbit changes when the asteroid is illuminated by the Sun; this Yarkovsky effect is very difficult to simulate, so direct observation of an occultation - the asteroid passes in front of a star - will give us greater precision of the asteroid's position," explained Franck Marchis, senior astronomer at the SETI Institute (USA) and chief scientist at Unistellar, in a statement.

This effect has been observed by astronomers at the University of Hawaii (United States), who update almost daily the data on the risk probabilities, as well as the danger of a possible collision in 2068, the expected date of impact.

Observing Apophis, the "god of chaos," is a vitally important action for the Earth, as the asteroid belongs to the subgroup of those that pass dangerously close to the planet, known as Aton asteroids.

In addition, many of them are categorized as potentially hazardous and, specifically, Apophis has a diameter of 340 meters, which poses a greater risk.

Since its discovery in 2004 by Dave Tholen and astronomers at the University of Hawaii, thanks to the Subaru telescope on Maunakea, Apophis has been closely followed, including these recent changes due to the Yarkovsky effect.

Unfortunately, astronomers used the Arecibo telescope (Puerto Rico) to observe objects like these, although it was dismantled in 2020, after several technical failures in its structure.

For this reason, Unistellar asked for help from the public and, in particular, from amateur astronomers, so that no details would be missed by the official Apophis researchers.

On the other hand, although the asteroid could be observed last February 21 across the United States, help from the public is still welcome, as the risk of Apophis impact remains active for the next few years.

Only the collaboration of all the people will be able to really defend the terrestrial citizens, who have their first enemy in this asteroid, the most dangerous that has ever grazed the Earth.

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Planetary defense plan activated: astronomers appeal to observe Apophis asteroid, which will graze Earth in... - Business Insider

The American Astronomical Society (AAS) is making the most of online opportunities during its 237th meeting, which will fully take place virtually this week due to the coronavirus pandemic.

The self-proclaimed "Super Bowl of Astronomy," which runs through Friday (Jan. 15), typically covers a wide range of topics, and this year's edition will be no different even though it will be fully online. The full agenda is available here. Some hot topics attendees can expect include fast radio bursts, dark matter, sky surveys, gravitational waves, and trying to understand why different teams have different measurements to calculate the expansion of the universe, among others.

AAS was already including iPosters (PowerPoint-like posters with combinations of text, images, video and audio) at its in-person meetings, along with short science talks, before the pandemic erupted last March. The society tested these meeting formats online with the June 2020 meeting, which was quickly moved online only weeks before starting as quarantine restrictions expanded across the United States.

Full coverage: The 237th American Astronomical Society meeting of 2021

Attendees can expect even more adaptations to online for AAS 237, press officer Rick Fienberg told Space.com in an e-mail interview.

"For AAS 237, we are adding 'Turbo Talks' 2-minute introductory videos by authors to draw attention and spur interest in their iPosters," he said. Other changes attendees can expect include Slack channels during the talks for people to "kibitz", Fienberg said, and spreading the meeting over five days instead of four to reduce the time attendees must spend at the computer each day.

The virtual exhibition hall will be very different than what attendees saw in June. This time around, AAS will use a meeting environment called vFairs, which allows sponsors and exhibitors to create custom-branded virtual booths, Fienberg said.

"They can post brochures and other files for download, have staff at the booth at certain times of day to interact with attendees one-on-one or in small groups, and offer webinars to introduce larger audiences of attendees to their products and services," he said.

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The ultimate goal is to attract more attendees to the virtual exhibition hall, mirroring the "coffee break" and "cocktail hour" experience one typically gets by wandering into the physical hall during an in-person meeting, he added.

"At our first virtual meeting in June, exhibitors didn't get the traffic theyre used to, for obvious reasons," Fienberg said. "So for January, we've set aside some dedicated time each day where the only activity is in the exhibit hall, and we've successfully encouraged nearly all our exhibitors to offer webinars, which are being listed in the program along with everything else so as not to get lost in the shuffle."

Student attendees can also look forward to the first-ever virtual "graduate school" and undergraduate research "experience fair" which will allow students to share CVs, meeting via text and video chat, and learn more about participating institutions all without the need of paying for in-person travel. People at all stages of their career can also take advantage of various social networking events, such as a trivia night, speed networking and a virtual scavenger hunt.

Looking back at the June meeting, Fienberg said the AAS staff "really had to scramble" to shift all activities online, including assembling the infrastructure, find vendors, and to bring members and other stakeholders along for the ride. The hard work paid off, as roughly 1,400 people attended the virtual activities double the expected attendance AAS thought it would see in-person in Madison, Wisc.

Fienberg said AAS has listened closely to attendee feedback in June to prepare for January; another change they are making is including two days of workshops that were not offered in June. The winter meeting typically has higher attendance than the summer meeting, with more sessions and activities as well.

"With five days of science sessions and two slots daily for press conferences, Ive scheduled 10 briefings rather than my usual eight, so I have 25% more presenters to communicate with plus their institutional public information officers," Fienberg said. "All of us involved in planning and executing the meeting are really quite exhausted already, but that's true when doing in-person meetings too. What we've learned over these two meetings is that a virtual meeting involves just as much work as an in-person one."

Fienberg added that some attendees have expressed worry about high registration fees for the virtual meeting, but he noted the infrastructure is not free. While venues and caterers are not required for online conferences, AAS is still working with vendors and software to deliver the best experience possible. "It's a fairly even trade," he said of the cost to AAS.

With a vaccine slowly rolling out in the United States and other countries, AAS is thinking ahead to when in-person meetings will be possible again in the coming months. Even before the pandemic erupted, members already were asking for virtual options due to cost and environmental concerns associated with activities like flying, Fienberg said. Journalists have been able to attend virtual press conferences for many years now, and Fienberg said the pandemic has caused even more types of attendees to strongly consider the online option.

"I think its inevitable that the meeting of the future will be hybrid," he said. "We just have to figure out how to make it work financially."

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.

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'Super Bowl of Astronomy' kicks off online due to global pandemic - Space.com

News releases | Research | Science

January 14, 2021

The sun is the only star in our system. But many of the points of light in our night sky are not as lonely. By some estimates, more than three-quarters of all stars exist as binaries with one companion or in even more complex relationships. Stars in close quarters can have dramatic impacts on their neighbors. They can strip material from one another, merge or twist each others movements through the cosmos.

And sometimes those changes unfold over the course of a few generations.

That is what a team of astronomers from the University of Washington, Western Washington University and the University of California, Irvine discovered when they analyzed more than 125 years of astronomical observations of a nearby stellar binary called HS Hydrae. This system is whats known as an eclipsing binary: From Earth, the two stars appear to pass over one another or eclipse one another as they orbit a shared center of gravity. The eclipses cause the amount of light emitted by the binary to dim periodically.

An image from the Digitized Sky Survey showing HS Hydrae in the center.Space Telescope Science Institute

On Jan. 11 at the 237th meeting of the American Astronomical Society, the team reported more than a centurys worth of changes to the eclipses by the stars in HS Hydrae. The two stars began to eclipse in small amounts starting around a century ago, increasing to almost full eclipses by the 1960s. The degree of eclipsing then plummeted over the course of just a half century, and will cease around February 2021.

There is a historical record of observations of HS Hydrae that essentially spans modern astronomy starting with photographic plates in the late 19th century up through satellite images taken in 2019. By diving into those records, we documented the complete rise and fall of this rare type of eclipsing binary, said team leader James Davenport, a research assistant professor of astronomy at the UW and associate director of the UWs DIRAC Institute.

The eclipses of the two stars that make up HS Hydrae are changing because another body most likely a third, unobserved companion star is turning the orientation of the binary with respect to Earth. Systems like this, which are called evolving eclipsing binaries, are rare, with only about a dozen known to date, according to Davenport. Identifying this type of binary requires multiple observations to look for long-term changes in the degree of dimming, which would indicate that the orientation of the binary is changing over time.

HS Hydrae has such an observational record because, at 342 light- years away, it is a relatively close and bright system and the two stars orbit each other every 1.5 days. Scientists first reported that HS Hydrae was an eclipsing binary in 1965. In a 2012 paper, astronomers based in Switzerland and the Czech Republic reported that the amount of dimming from HS Hydrae decreased from 1975 through 2008, indicating that the two stars were eclipsing smaller and smaller portions of one another over time. That team also predicted that the eclipses would end around 2022.

Davenport and his team checked in on HS Hydrae using observations of the system in 2019 by the NASAs Transiting Exoplanet Survey Satellite, or TESS. They saw only a 0.0075-magnitude drop in light from HS Hydrae, a sign that the two stars were barely covering one another during eclipses. For comparison, eclipses in 1975 saw a more than 0.5-magnitude drop.

Fifty years ago, these two stars were almost completely eclipsing each other. By the early 21st century, the degree of eclipse was around 10%, and in the most recent observations from 2019, they barely overlapped, said Davenport.

With these new data, the team now predicts that HS Hydrae eclipses will cease around February 2021.

Image of a photographic plate from 1945, which was digitized for the Digital Access to a Sky Century at Harvard, or DASCH, catalog.DASCH/Harvard University

The observations from the 1960s through 2019 catalogue the decline of HS Hydrae as an evolving eclipsing binary. But Davenport and his team also uncovered evidence for its rise. The Digital Access to a Sky Century at Harvard, or DASCH, is a digital catalog of photometric data taken from more than a centurys worth of astro-photographic plates at Harvard University. The team mined this record and found observations of HS Hydrae from 1893 through 1955 that they could analyze to search for signs of dimming.

The researchers broke down DASCH observations of HS Hydrae by decade. From the late 19th century through the roaring 20s, HS Hydrae showed no measurable dimming. But things began to change in the 1930s, where they measured a modest 0.1-magnitude drop in brightness. The degree of dimming rose through the 1940s and peaked in the 1950s with a 0.5-magnitude drop in brightness.

Based off this 126-year history of HS Hydrae observations, the team predicts that the system will start eclipsing again around the year 2195. But, that assumes that the third companion which other teams have predicted is a small, dim M-dwarf star continues to behave as it has to date.

Image of an astronomical log book from 1945. These observations are now part of the Digital Access to a Sky Century at Harvard, or DASCH, catalog.DASCH/Harvard University

We wont know for sure unless we keep looking, said Davenport. The best we can say right now is that HS Hydrae has been changing constantly over the course of modern astronomy.

Missions like TESS will likely identify more evolving eclipsing binaries in the coming years. This should open new opportunities for astronomers to understand how star systems are built, as well as how they change over time whether they are busy, dynamic systems like HS Hydrae, or more quiet systems, like ours.

Co-authors on the paper are UW graduate students Diana Windemuth and Jessica Birky; UW researcher Karen Warmbein; Erin Howard at Western Washington University; and Courtney Klein at UC Irvine. The research was funded by NASA, the National Science Foundation, the Heising-Simons Foundation, the Research Corporation for Science Advancement, the DIRAC Institute, the UW Department of Astronomy, the Charles and Lisa Simonyi Fund for Arts and Sciences and the Washington Research Foundation.

For more information, contact Davenport at jrad@uw.edu.

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Astronomers document the rise and fall of a rarely observed stellar dance - UW News

Astronomers have, for the first time, witnessed the death of a distant galaxy, which they describe as a "truly extreme event."

When all of the stars in a galaxy die, and new ones are no longer forming, the galaxy itself ceases to exist. This occurs when all of the galaxy's gas is ejected, making it impossible for new stars to form.

According to a study published Monday in the journal Nature Astronomy, scientists were "thrilled" to be able to capture this rare phenomenon recently using the Atacama Large Millimeter/submilimeter Array of telescopes in Chile.

It has taken about nine billion years for the light from the starburst galaxy ID2299 to reach Earth. So, when astronomers happened to observe it by chance, they witnessed the universe as it appeared at just 4.5 billion years old.

Astronomers say that ID2299 is losing 10,000 suns worth of gas each year rapidly depleting fuel needed to form new stars. This startling release of gas appears to be the result of two galaxies violently colliding and merging together to create ID2299.

The galaxy is also currently forming stars at a rate hundreds of times faster than the Milky Way using up the rest of its precious gas supply. Because of this, ID2299 is expected to die relatively soon, in just a few tens of thousands of years.

"This is the first time we have observed a typical massive star-forming galaxy in the distant universe about to 'die' because of a massive cold gas ejection," lead author Annagrazia Puglisi said in a statement.

Astronomers believe the phenomenon is the result of galaxies merging because they were able to witness a rare "tidal tail," usually too faint to see in distant galaxies. This elongated stream of stars and gas, astronomers suggest, is the direct result of the galactic merger.

They only observed the galaxy for a few minutes, but it was enough to spot the elusive tidal tail.

"Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar," says study co-author Emanuele Daddi. "This might lead us to revise our understanding of how galaxies 'die.'"

If the astronomers are correct that the merger led to the massive loss of gas, they will need to reconsider prior theories on how galaxies form and evolve and how they die. Other theories have suggested that wind from active black holes or intense star formations are responsible for such deaths.

"Studying this single case unveiled the possibility that this type of event might not be unusual at all and that many galaxies suffered from this 'gravitational gas removal', including misinterpreted past observations,"said co-author Dr. Jeremy Fensch.

"This might have huge consequences on our understanding of what actually shapes the evolution of galaxies."

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Astronomers observe the death of a distant galaxy for the first time - CBS News

When stars in a galaxy stop forming, that galaxy will die. Astronomers, for the first time ever, have observed this phenomenon in a distant galaxy.

According to a report by CNN, scientists using the Atacama Large Millimeter/submillimeter Array of telescopes in Chile, were able to capture a rare observation of a galaxy as it ejected almost half of the gas it uses to form stars.

It has taken nearly nine billion years for the light from this galaxy, known as ID2299, to reach Earth, CNN reported - which means essentially astronomers are observing how it appeared when the universe was only 4.5 billion years old (its now estimated to be 14 billion years old).

The ID2299 galaxy is losing the fuel it needs to form stars - 10,000 suns-worth of gas per year - and so far has removed 46% of the galaxys total cold gas, the report explained.

However, at a rate that is hundreds of times faster than our own Milky Way, ID2299 is still quickly forming stars, the report noted.

The formation of these stars will deplete the remainder of the gas in the galaxy, and will effectively cause ID2299 to die in a few tens of million years, the report explained.

The study, which CNN has cited, was published Monday in the journal Nature Astronomy.

CNN cited Annagrazia Puglisi, lead study researcher and postdoctoral research associate from Durham University in the UK and the Saclay Nuclear Research Centre in France, who said in a statement: This is the first time we have observed a typical massive star-forming galaxy in the distant Universe about to die because of a massive cold gas ejection.

What may have caused the galaxys demise?

According to the report, the cause of this galaxys death, may have been a collision with another galaxy, which eventually merged to create ID2299.

Is there compelling evidence that the loss of gas may have been the result of a collision? According to the CNN report, the study says there is - and its called a tidal tail - a long stream of gas and stars that extend out into space after two galaxies come together in a collision.

Although these tidal tails are typically too faint to be seen in galaxies of this distance, the study noted that in this case the bright tail was visible to astronomers as it was extending out into space, CNN reported.

Astronomers may need to reconsider previous theories.

Previously, scientists have believed that the ending of star formation happened when the winds created by the formation of stars, combined with active black holes at the centers of giant galaxies, sent the material needed to form stars hurtling out into space, CNN cited.

However, the study noted that if this galaxys loss of gas was caused by a merger, astronomers may need to reconsider theories on the end of star formation in galaxies.

CNN cited Emanuele Daddi, study coauthor and astronomer at the Saclay Nuclear Research Centre in France, who said: Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar. He added, This might lead us to revise our understanding of how galaxies die.

This observation was an unexpected discovery.

An interesting aspect about this discovery is that it was made while the astronomers were working on a different survey of cold gas in distant galaxies, and although their observation of ID2299 only lasted a few minutes, it was enough to capture the tidal tail, CNN reported. And, the possibility remains that more could be revealed about the galaxys gas ejection, through future observations.

CNN cited Chiara Circosta, study coauthor and researcher at the University College London, who said in a statement: ALMA has shed new light on the mechanisms that can halt the formation of stars in distant galaxies. Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution.

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Astronomers have witnessed a distant galaxy die for the first time - PennLive

Gravitational-wave astronomy is still in its infancy. LIGO and other observatories have opened a new window on the universe, but their gravitational view of the cosmos is limited. To widen our view, we have the North American Nanohertz Observatory for Gravitational Waves (NANOGrav).

Gravitational waves are created by the motion of massive objects. Most of the gravitational waves weve detected come from the merger of black holes. In their last moments, binary black holes orbit each other very quickly, producing rapid and strong gravitational waves. But most of the gravitational waves rippling through the universe are neither rapid nor strong. They are the faint echoes of orbiting black holes that arent about to merge. Their slow orbits create a background of gravitational waves. A single wave from one of these sources can take years to make a complete cycle.

To detect these gravitational waves, NANOGrav observes radio pulses from rapidly rotating neutron stars known as millisecond pulsars. Most of these pulsars are very regular, so a shift change in their pulse rate is caused by a change in their motion relative to Earth. Essentially, NANOGrav is like LIGO but on the scale of our galaxy. But because these background gravitational waves oscillate so slowly, it takes years to observe a shift of the pulsars due to them.

NANOGrav has been watching pulsars for more than a dozen years, and theyve just published some initial results. In the study, the team looked at 45 millisecond pulsars they know have very steady pulse rates. Some of them have been observed for 12.5 years, but all of them have been observed for at least 3 years. When they filtered out spurious noise effects, they found what appears to be a background signal of gravitational waves with an oscillation period of about a year. They cant prove that gravitational waves are the origin of this signal, but they have ruled out other possibilities, including any bias in their data.

While a decade of observations seems like a long time, its just a moment in time for many of these gravitational waves. To understand them better we will need to keep watching for much longer.

Reference: Arzoumanian, Zaven, et al. The NANOGrav 12.5 yr Data Set: Search for an Isotropic Stochastic Gravitational-wave Background. The Astrophysical Journal Letters 905.2 (2020): L34.

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Astronomers see a Hint of the Gravitational Wave Background to the Universe - Universe Today

This combination photo shows the different stages of a total super moon lunar eclipse as viewed from Los Angeles on Jan. 20, 2019. On the morning of May 26, Coloradans will get to see a similar eclipse as the moon is setting if the weather cooperates. (Ringo H.W. Chiu, Associated Press file)

Lets hope the sky is crystal clear in Colorado just before dawn on the morning of May 26.

If it is, Front Range residents will be treated to a very special lunar eclipse appearing to hang just above the mountains as part of a confluence of events that figures to be the highlight of the celestial calendar for 2021.

First of all, the moon will be full, and it will be a super moon. That means the moon will be closer to the earth just over 222,000 miles away than for any other full moon this year. And remember, the moon always looks bigger when it is rising and setting than it does when its overhead. (Scientists tell us that is just an optical illusion, but it sure is a convincing one.)

Thats already a cool aspect of the timing for this eclipse. But heres where it gets really exciting: The moon will be low in the western sky when the eclipse begins at 5:11 a.m., while the sky is turning twilight blue with the approach of sunrise. The eclipse will reach its maximum at 5:18, the sun will rise at 5:36 and the moon will set at 5:43.

Were already thinking about cool places to watch the show. The Genesee overlook on Interstate 70, where the moon would be seen hanging over the Continental Divide, could be an amazing vantage point.

What I think will be really cool is that it will be setting in the west over the Rocky Mountains for folks in the Front Range, and its going to be just coming out of totality (of eclipse) as it sets, said John Keller, the director of the Fiske Planetarium on the University of Colorados Boulder campus. For that 45 minutes or so when it is in full totality, it will be a rusty reddish color. You will be seeing the red refracted light from our atmosphere making the otherwise dark moon glow.

Indeed, Keller says one of the things that makes this eclipse special is that theres more to the show than the alignment of the sun, the Earth and the moon. He thinks we should give extra props to the influence of Earths atmosphere.

If the Earth didnt have an atmosphere, we would still have eclipses, but the eclipse in May would be very different, Keller said. One, the moon wouldnt be lit up because there wouldnt be any bending of the red light (through Earths atmosphere) to give you the reddening of the moon, And two, there wouldnt be any light blue twilight as the sun is rising, because our atmosphere is doing both. Its scattering the blue light and its bending the red light. So this combination of the reddish setting moon in a bluish predawn sky is really as much about the alignment of the three objects as it is about our atmosphere playing a huge light show for us.

Another lunar eclipse will be visible in Denver on Nov. 19, but that one is only partial. And while the moon will be full for that one, too, it will be farther away (251,000 miles, 29,000 more than in May). Plus, it will take place in the wee hours after midnight.

With that as an appetizer, heres a list of other celestial events to put on your calendar for 2021:

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Astronomy 2021: The biggest events including a super moon lunar eclipse - The Know

This Hubble Space Telescope portrait reveals the gaseous remains of an exploded massive star that erupted approximately 1,700 years ago. The stellar corpse, a supernova remnant named 1E 0102.2-7219, met its demise in the Small Magellanic Cloud, a satellite galaxy of our Milky Way. Credit: NASA, ESA, and J. Banovetz and D. Milisavljevic (Purdue University)

Astronomers are winding back the clock on the expanding remains of a nearby, exploded star. By using NASAs Hubble Space Telescope, they retraced the speedy shrapnel from the blast to calculate a more accurate estimate of the location and time of the stellar detonation.

The victim is a star that exploded long ago in the Small Magellanic Cloud, a satellite galaxy to our Milky Way. The doomed star left behind an expanding, gaseous corpse, a supernova remnant named 1E 0102.2-7219, which NASAs Einstein Observatory first discovered in X-rays. Like detectives, researchers sifted through archival images taken by Hubble, analyzing visible-light observations made 10 years apart.

The research team, led by John Banovetz and Danny Milisavljevic of Purdue University in West Lafayette, Indiana, measured the velocities of 45 tadpole-shaped, oxygen-rich clumps of ejecta flung by the supernova blast. Ionized oxygen is an excellent tracer because it glows brightest in visible light.

To calculate an accurate explosion age, the astronomers picked the 22 fastest moving ejecta clumps, or knots. The researchers determined that these targets were the least likely to have been slowed down by passage through interstellar material. They then traced the knots motion backward until the ejecta coalesced at one point, identifying the explosion site. Once that was known, they could calculate how long it took the speedy knots to travel from the explosion center to their current location.

According to their estimate, light from the blast arrived at Earth 1,700 years ago, during the decline of the Roman Empire. However, the supernova would only have been visible to inhabitants of Earths southern hemisphere. Unfortunately, there are no known records of this titanic event.

The researchers results differ from previous observations of the supernovas blast site and age. Earlier studies, for example, arrived at explosion ages of 2,000 and 1,000 years ago. However, Banovetz and Milisavljevic say their analysis is more robust.

This time-lapse video shows the movement of a supernova remnantthe gaseous remains of an exploded starthat erupted approximately 1,700 years ago. The stellar corpse, a supernova remnant named 1E 0102.2-7219, met its demise in the Small Magellanic Cloud, a satellite galaxy of our Milky Way. The movies opening frame shows ribbons of glowing gaseous clumps that make up the remnant. The video then toggles between two black-and-white images of the remnant, taken 10 years apart, revealing subtle shifts in the ejectas expansion over time. Credit: NASA, ESA, A. Pagan (STScI), J. Banovetz and D. Milisavljevic (Purdue University)

A prior study compared images taken years apart with two different cameras on Hubble, the Wide Field Planetary Camera 2 and the Advanced Camera for Surveys (ACS), Milisavljevic said. But our study compares data taken with the same camera, the ACS, making the comparison much more robust; the knots were much easier to track using the same instrument. Its a testament to the longevity of Hubble that we could do such a clean comparison of images taken 10 years apart.

The astronomers also took advantage of the sharp ACS images in selecting which ejecta clumps to analyze. In prior studies, researchers averaged the speed of all of the gaseous debris to calculate an explosion age. However, the ACS data revealed regions where the ejecta slowed down because it was slamming into denser material shed by the star before it exploded as a supernova. Researchers didnt include those knots in the sample. They needed the ejecta that best reflected their original velocities from the explosion, using them to determine an accurate age estimate of the supernova blast.

Hubble also clocked the speed of a suspected neutron starthe crushed core of the doomed starthat was ejected from the blast. Based on their estimates, the neutron star must be moving at more than 2 million miles per hour from the center of the explosion to have arrived at its current position. The suspected neutron star was identified in observations with the European Southern Observatorys Very Large Telescope in Chile, in combination with data from NASAs Chandra X-ray Observatory.

That is pretty fast and at the extreme end of how fast we think a neutron star can be moving, even if it got a kick from the supernova explosion, Banovetz said. More recent investigations call into question whether the object is actually the surviving neutron star of the supernova explosion. It is potentially just a compact clump of supernova ejecta that has been lit up, and our results generally support this conclusion.

So the hunt may still be on for the neutron star. Our study doesnt solve the mystery, but it gives an estimate of the velocity for the candidate neutron star, Banovetz said.

Banovetz presented the teams findings on January 14, 2021, at the American Astronomical Societys winter meeting.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASAs Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

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Astronomers Rewind the Clock to Calculate Age of Supernova Blast From Massive Star Explosion - SciTechDaily

A visualization of how the timing of millisecond pulsar flashes is being used in a project aimed at confirming the presence of low-frequency gravity waves by measuring their effects on Earths position in space. Image: NANOGrav/T. Klein

Monitoring the timing of millisecond pulsar flashes over the past 13 years, astronomers have detected subtle changes that may indicate Earth is bobbing in an ocean of low-frequency gravity waves generated by supermassive black holes, researchers say.

Speaking in a virtual news conference hosted by the 237th meeting of the American Astronomical Society, Joseph Simon of the University of Colorado at Boulder said the North American Nanohertz Observatory for Gravitational Waves NANOGrav monitored 45 pulsars using the Greenbank Radio Telescope and the now-collapsed Arecibo Observatory.

The result is a pulsar timing array in which we monitor the signals from a large number of these objects, Simon said. We actually create a galaxy-size gravitational wave detector within our own Milky Way.

Here on the Earth, were actually kind of bobbing in an ocean of low frequency gravitational waves. And as these waves pass, the Earth gets kind of pushed around very slightly, very slowly, in slightly different directions.

By comparing slight changes in the timing of flashes from the fast-spinning pulsars, researchers hope to show how the Earth is moving about ever so slightly in a presumed sea of gravity waves.

As the Earth is pushed closer to a pulsar, the pulses from that object appear to come a little bit sooner than we expect, Simon said. And as the stretching and squeezing of spacetime from these gravitational waves continues to happen and the Earth moves away, then those pulses come a little bit later. Its kind of like a Doppler shift, but not exactly.

Unlike the LIGO and Virgo collaborations, which are primarily focused on high-frequency gravity waves produced by pairs of black holes and neutron stars, NANOGrav is looking or a persistent low-frequency background of gravitational waves created over billions of years by pairs of supermassive black holes.

While the results outlined in a paper published in the Astrophysical Journal Supplements are consistent with low-frequency gravity waves, they are not yet definitive. To confirm direct detection of such background gravity radiation will requite more pulsar observations over even longer periods.

Trying to detect gravitational waves with a pulsar timing array requires patience, Scott Ransom, the current chairperson of NANOGrav, said in a statement. Were currently analysing over a dozen years of data, but a definitive detection will likely take a couple more. Its great that these new results are exactly what we would expect to see as we creep closer to a detection.

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Researchers find strong hints of background 'sea' of gravity waves - Astronomy Now Online