Daily Archives: January 17, 2021

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

While the days are short, the weather is bleak, and the sky is grey - its nice to know that there are some astronomical phenomena that you can look forward in 2021.

Meteor showers, New Moons, and even a partial solar eclipse - get ready, 2021 is going to be a busy year!

While it might be a little late in the month to catch sight of the Quadrantids Meteor Shower, you still have plenty to enjoy in January. January 13 will mark the first New Moon of 2021, and on January 28 you can enjoy the first Full Moon of the year!

Sadly there wont be much going on in February, but there will be a New Moon on February 11, plus as 2021 isnt a leap year, you get to enjoy to beautiful symmetry of the 28-day month as it starts on a Monday and ends on a Sunday - so satisfying!

Heading into the spring, March offers a little more excitement with the Equinox on March 20. In April, not only will you be treated to the peak of the Lyrids Meteor Shower between April 22 and 23, but youll also get a Super Full Moon on April 27. This happens when the moon and sun appear directly opposite each other, fully illuminating the surface of the moon - which mean it could look up to 14 percent bigger and 30 percent brighter than your average full moon.

In May there will be another meteor shower - the Eta Aquarids Meteor Shower - which will be at its peak on May 6 to 7, but runs all the way from the end of April right through to May 28, as well as another Super Full Moon on May 26! This is the closest the moon will get to earth all year, so you definitely wont want to miss it! On top of this, if you happen to be outside of the Netherlands on the same day, youll likely get to witness a total lunar eclipse.

If you think the spring sounded exciting, get ready to hear what summer 2021 has in store. June 10 will see a partial solar eclipse for Europe and the US (or a total eclipse in eastern Russia, the Arctic Ocean, Western Greenland and Canada). June is also, of course, the month of the Summer Solstice (June 21).

Going into July, if you look to the sky just after sunset on July 13 you might be lucky enough to see the conjunction of Mars and Venus - the angle from Earth will mean that the two planets will appear as one. Between July 12 and August 13 you also have the chance of spying the Delta Aquarids Meteor Shower, with the peak on July 28 to 29.

August is another big month. From July 17 to August 24 you might be able to spot the Perseids Meteor Shower (with the peak on the night of August 12). 2021 is set to be a good year for this shower as a waxing crescent moon on August 12 will set in the early evening, guaranteeing dark skies - perfect for watching a meteor shower.

August 2 will offer a great opportunity to spot a fully-illuminated Saturn in the night sky, while August 19 will be a good night to see Jupiter, which will be brighter than any other time of year and will be visible all night long. In addition to all this astronomical goodness, August 22 will see a Blue Moon.

If youre looking to see some more planets, then keep your telescope at the ready in September and November: similarly to August, September 14 will offer a perfect opportunity to spot Neptune, while November 5 will give you a glimpse of Uranus. Make the most of this chance because, due to their size and distance from the Earth, you dont get very many opportunities to see these two planets.

October is bookended by two meteor showers: the Draconids Meteor Shower, which runs from October 6 to 10 with the peak on October 7; and the Orionids Meteor Shower, which runs from October 2 to November 7 with the peak on October 21. For the Draconids you probably wont have to stay up too late (unusually, the best viewing time is actually in the early evening), while the Full Moon might make it a little tricky to spot the Orionids.

Still looking for more meteor showers? Well, November doesnt disappoint. On November 4 youll be treated to the peak of the Taurids Meteor Shower, and on November 17 youll get the peak of the Leonids Meteor Shower, which runs from November 6 through to November 30.

Then, as 2021 rounds to a close and everyone decorates the Christmas tree, orders the turkey, and buys the gifts, youll be treated to one last astronomical gift: the Geminids Meteor Shower. Running from December 7 to 17, the showers peak is on December 13, where - if the Dutch weather holds out - you could be treated to a whopping 120 multicoloured meteors per hour!

Telescopes and blankets at the ready everyone! Get ready to camp out under the stars and enjoy all the beautiful wonders our solar system has to offer - here's just hoping the sky stays clear enough for you to actually see it all happen!

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From meteor showers to New Moons: The astronomy calendar for 2021 - IamExpat in the Netherlands