Tag: astronomy

Astronomers detect 1st evidence of neutron star left behind after 1987 supernova

10:42 am

The uncertainty of science: More than three decades after the 1987 supernova in the Large Magellanic Cloud, the only naked eye supernova in the 400 years, astronomers think they might finally have detected evidence of the neutron star left over from that blast and buried within the explosion’s wake.

“Astronomers have wondered if not enough time has passed for a pulsar to form, or even if SN 1987A created a black hole,” said co-author Marco Miceli, also from the University of Palermo. “This has been an ongoing mystery for a few decades and we are very excited to bring new information to the table with this result.”

The Chandra and NuSTAR data also support a 2020 result from ALMA that provided possible evidence for the structure of a pulsar wind nebula in the millimeter wavelength band. While this “blob” has other potential explanations, its identification as a pulsar wind nebula could be substantiated with the new X-ray data. This is more evidence supporting the idea that there is a neutron star left behind.

If this is indeed a pulsar at the center of SN 1987A, it would be the youngest one ever found.

The data is still somewhat tentative and unconfirmed, but intriguing nonetheless. The pulsar itself, if it really is a pulsar, remains buried in the explosion’s expanding cloud, and has as yet not been seen directly.

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New 3D atlas of all binary stars within 3,000 light years of Sun

9:45 am

Using data from Europe’s Gaia satellite, astronomers have now compiled a 3D map of every binary star within 3,000 light years of the the Sun — 1.3 million — including many widely spaced binaries that were previously not identified.

The one-of-a-kind atlas, created by Kareem El-Badry, an astrophysics Ph.D. student from the University of California, Berkeley, should be a boon for those who study binary stars — which make up at least half of all sunlike stars — and white dwarfs, exoplanets and stellar evolution, in general. Before Gaia, the last compilation of nearby binary stars, assembled using data from the now-defunct Hipparcos satellite, included about 200 likely pairs. “This is just a massive increase in sample size,” said El-Badry. “And it is an increase in what kinds of evolutionary phases we find the binaries in. In our sample, we have 17,000 white dwarfs alone. This is a much bigger census.”

The data has also shown that the bulk of these binaries are made up of twins, stars similar in mass, something that is surprising and as yet unexplained, especially for binaries where the stars are widely separated.

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Possible exoplanet detected in habitable zone around Alpha Centauri A?

10:47 am

The uncertainty of science: Scientists have detected faint evidence that suggests the existence of a Neptune-sized exoplanet circling the sunlike star Alpha Centauri A.

After analyzing 100 hours of data gathered by NEAR in May and June of 2019, the scientists detected a thermal fingerprint in the habitable zone of Alpha Centauri A. The signal potentially corresponds to a roughly Neptune-size world orbiting between 1 and 2 astronomical units (AU) from the star, study team members said. (One AU, the average Earth-sun distance, is about 93 million miles, or 150 million kilometers.)

But that planet has not yet been confirmed, so it remains a candidate for now.

This result is very uncertain at this moment, so we should constrain our enthusiasm. If true, however, it would signal the possibility of more exoplanets circling the stars of the nearest stellar system. Alpha Centauri is actually three stars, a binary of two sunlike stars circled at great distance by the red dwarf Proxima Centauri. Scientists already think there are exoplanets circling Proxima, with one about the size of Earth.

What makes this particular interesting, if true, is that the exoplanet was detected not by the slight wobble its gravity caused in the star, or by a transit across the face of the star, but by its own light. If the detection is real, this would be I think the first time that an exoplanet has been seen directly, even if that detection comprises a few tiny pixels of light.

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Scientists confirm distance to farthest known solar system object

2:46 pm

Scientists have now confirmed that the large asteroid dubbed Farfarout (about 250 miles across) is presently about 132 astronomical units from the Sun (about 12 billion miles), making it the farthest known solar system object.

Its orbit however is far from circular, and it isn’t presently even at its farthest point in that orbit.

[T]he orbit of Farfarout is quite elongated, taking it 175 au from the Sun at its farthest point and around 27 au at its closest, which is inside the orbit of Neptune. Because its orbit crosses Neptune’s, Farfarout could provide insights into the history of the outer Solar System. “Farfarout was likely thrown into the outer Solar System by getting too close to Neptune in the distant past,” said Trujillo. “Farfarout will likely interact with Neptune again in the future since their orbits still intersect.”

The astronomers expect to discover more such objects in the coming years that will even eclipse this one in distance.

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Betelgeuse is closer and smaller than previously thought

12:12 pm

Betelgeuse's fading
Images taken by Europe’s
Very Large Telescope in Chile

The uncertainty of science: A new analysis by scientists of Betelgeuse, triggered by its dip in brightness in 2020, has concluded that the red giant star is both closer and smaller than previously estimated.

Their analysis reported a present-day mass of 16.5 to 19 solar mass—which is slightly lower than the most recent estimates. The study also revealed how big Betelgeuse is, as well as its distance from Earth. The star’s actual size has been a bit of a mystery: earlier studies, for instance, suggested it could be bigger than the orbit of Jupiter. However, the team’s results showed Betelgeuse only extends out to two-thirds of that, with a radius 750 times the radius of the sun. Once the physical size of the star is known, it will be possible to determine its distance from Earth. Thus far, the team’s results show it is a mere 530 light years from us, or 25 percent closer than previously thought.

The research also suggested that the star is in the initial stages of burning helium rather than hydrogen, and so it likely more than 100,000 years from going supernova.

As for the dimming, the scientists concluded (as other have) that the dimming in ’20 was due to the passage of a dust cloud in front of the star.

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New radar technology now available for radio astronomy

9:47 am

GreenBank radar image of Apollo 15 landing region

Astronomers have now demonstrated a spectacular new radar technology using radio telescopes and capable of producing high resolution images of all solar system bodies, as far away as Neptune.

[S]cientists built a miniature transmitter, powered at less than a kilowatt and about the size of a refrigerator, Beasley said, and in November hauled it up for a brief stint at the prime focus of Green Bank Telescope, suspended over the large dish.

Then, the team took advantage of the telescope’s superlative: It’s the largest fully steerable radio telescope in the world, able to study objects across 85% of the sky. So the team pointed the telescope and fired the radar system at the moon — more specifically, at the Apollo 15 mission’s landing site in the Hadley-Apennine region [the white dot in the image to the right]. The team used antennas of the NRAO’s Very Long Baseline Array (VLBA) to catch the signal that bounced back.

The image, with its sloping hills, stark crater and slinking rille, offers a hint of what could come. But the moon is our old companion. Scientists would much rather use a shiny new planetary radar system to study more mysterious objects, like the asteroids zipping through our neighborhood of the solar system, most of which are blurs and blobs, or the strange moons of the outer planets that have received few spacecraft visitors.

Without question this technology would be a major breakthrough for the observation of asteroids, especially those that are considered a threat of impacting the Earth for which we have little concrete information.

The article however notes that the technology had been developed with the assumption that the Arecibo radio telescope would be available. That telescope however is now dead, having been destroyed when its instrument platform fell in early December. With a limited number of radio telescopes available, all of which are oversubscribed for other work, it will be difficult to find time for the use of this technology on any of them.

But don’t worry. The Chinese will definitely want to steal it and put it on their giant FAST radio telescope, and I am sure the Biden administration will be agreeable to letting them.

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Astronomers discover first periodic erupting supermassive black hole

11:40 am

Astronomers observing a galaxy 570 million light years away have discovered that the periodic energetic flares that occur there every 114 days are not supernovae but eruptions from the supermassive black hole at the center of the galaxy, caused each time an orbiting star gets too close during its perihelion and has material stripped away from it.

ASASSN-14ko was first detected by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global network of 20 robotic telescopes headquartered at The Ohio State University (OSU) in Columbus. When Payne examined all the ASAS-SN data on the phenomenon, she noticed a series of 17 regularly spaced flares.

Based on this discovery, the astronomers predicted that the galaxy would experience another burst on May 17 of last year and coordinated ground- and space-based facilities to make observations. They have since successfully predicted and witnessed flares on September 7 and December 26.

Though the press release tries to sell itself by saying these flares were initially mistaken for supernovae, a close reading suggests the astronomers thought this for only a very short time. As soon as they took their first close look and noticed the regularly space events, they abandoned the supernovae idea immediately.

Most supermassive black holes at the center of galaxies are active, emitting large amounts of energy in bursts or in a steady stream. That is why astronomers label them Active Galactic Nuclei, or AGNs. This is the first to do so in a periodic manner.

That most are active illustrates the mystery of the supermassive black hole in the center of the Milky Way. Sagittarius A* (pronounced A-star) is not active, even though it really should be.

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Colliding galaxies!

2:19 pm

Colliding galaxies!
Click here and here to see full images.

Cool images from Hubble! The two photos to the right, cropped and reduced to post here, shows two different galaxies undergoing a collision with another galaxy. Both images are from of a montage of six galaxy merger images from the Hubble Space Telescope, released yesterday.

To celebrate a new year, the NASA/ESA Hubble Space Telescope has published a montage of six beautiful galaxy mergers. Each of these merging systems was studied as part of the recent HiPEEC survey to investigate the rate of new star formation within such systems. These interactions are a key aspect of galaxy evolution and are among the most spectacular events in the lifetime of a galaxy.

It is during rare merging events that galaxies undergo dramatic changes in their appearance and in their stellar content. These systems are excellent laboratories to trace the formation of star clusters under extreme physical conditions.

The first galaxy merger to the right is dubbed NGC 6052, and is located in the constellation of Hercules about 230 million light-years away. This pair of colliding galaxies, according to the caption, “were first discovered in 1784 by William Herschel and were originally classified as a single irregular galaxy because of their odd shape. However, we now know that NGC 6052 actually consists of two galaxies that are in the process of colliding.”

The second image shows two galaxies, IC 694 and NGC 3690, about 700 millions after they had completed a close pass of each other. From the caption: “As a result of this interaction, the system underwent a fierce burst of star formation. In the last fifteen years or so six supernovae have popped off in the outer reaches of the galaxy, making this system a distinguished supernova factory.”

You can see all six merger images here, though to my eye these two are the most impressive.

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Surprisingly low number of observation proposals from astronomers for Webb telescope

4:03 pm

In preparation for the launch of the James Webb Space Telescope in ’21, the Space Telescope Science Institute (STScI) that will operate it has begun accepting observation proposals from astronomers, and has apparently discovered that the number of proposals, dubbed the subscription rate, is surprisingly low.

The stats of the James Webb space telescope cycle 1 proposal round came in the other day. In summary: an over subscription rate of 1:4. A little less even.

There was immediate spin how the stats were a good thing. Enthusiasm from around the globe! So many investigators! But that does not change that the 1:4 oversubscription is a disappointment. If I were part of the project, this would and should worry me.

If they got exactly the right number of proposals to precisely use all of the telescope’s observation time, the subscription rate would be 1. An oversubscription rate of 1.4 seems good, but in truth it is tiny compared to Hubble and other space telescopes, and horrible considering the cost of Webb (almost $10 billion, 20x what it was originally budgeted).

The author at the link provides some technical reasons for the low interest, some of which are the fault of the Webb management team (such as a very complicated proposal process) and some that are beyond their control (the Wuhan panic). He also provides suggestions that might help.

Either way, the relatively low interest I think is rooted in Webb’s initial genesis. It was pushed by the cosmological community and its design thus optimized for studying the early universe. Other astronomical fields were pushed aside or given a lower priority so that the telescope does not serve them as well.

The result is that a lot of astronomers have been finding other more appropriate and already functioning telescopes to do their work, bypassing Webb entirely. They are probably also bypassing Webb because it seems foolish to spend the inordinate amount of time putting together a proposal for a telescope a decade behind schedule that carries an enormous risk of failure once it is launched.

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Puerto Rican government commits $8 million to rebuild Arecibo

8:16 am

The government of Puerto Rico earlier this week announced that it has allocated $8 million to rebuild the Arecibo Observatory.

Via an executive order, Gov. Wanda Vazquez made reconstruction of the observatory public policy. In a ceremony at La Fortaleza, the seat of the island’s government, Vazquez said that the Puerto Rican government believes that the telescope’s collapse provides a great opportunity to redesign it, taking into account the lessons learned and recommendations from the scientific community so that it remains relevant for decades to come.

…Vazquez said that she and her administration want the scope to once again become a world class center and the $8 million being allocated for reconstruction includes funds to repair the environmental damage caused by the collapse, something that has already begun under the supervision of the National Science Foundation (NSF).

We shall see what happens. $8 million is not really enough to rebuild Arecibo. And the NSF has been trying to unload it from its budgetary responsibility for almost a decade. I would be shocked if that agency now suddenly decided to fund its reconstruction.

Only if Congress gets involved will this likely change, and that wouldn’t surprise me, considering how nonchalant our present Congress is about spending money that doesn’t exist.

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Mysterious signal detected possibly coming from Proxima Centauri

9:05 am

The uncertainty of science: Breakthough Listen, the project funded to the tune of $100 million by billionaire Yuri Milner with the goal of listening for alien radio signals, in 2019 detected a single radio tone that appeared to be coming from the nearest star, Proxima Centauri.

A team had been using the Parkes radio telescope in Australia to study Proxima Centauri for signs of flares coming from the red dwarf star, in part to understand how such flares might affect Proxima’s planets. The system hosts at least two worlds. The first, dubbed Proxima b upon its discovery in 2016, is about 1.2 times the size of Earth and in an 11-day orbit. Proxima b resides in the star’s “habitable zone,” a hazily defined sector in which liquid water could exist upon a rocky planet’s surface—provided, that is, Proxima Centauri’s intense stellar flares have not sputtered away a world’s atmosphere. Another planet, the roughly seven-Earth-mass Proxima c, was discovered in 2019 in a frigid 5.2-year orbit.

Using Parkes, the astronomers had observed the star for 26 hours as part of their stellar-flare study, but, as is routine within the Breakthrough Listen project, they also flagged the resulting data for a later look to seek out any candidate SETI signals. The task fell to a young intern in Siemion’s SETI program at Berkeley, Shane Smith, who is also a teaching assistant at Hillsdale College in Michigan. Smith began sifting through the data in June of this year, but it was not until late October that he stumbled upon the curious narrowband emission, needle-sharp at 982.002 megahertz, hidden in plain view in the Proxima Centauri observations. From there, things happened fast—with good reason. “It’s the most exciting signal that we’ve found in the Breakthrough Listen project, because we haven’t had a signal jump through this many of our filters before,” says Sofia Sheikh from Penn State University, who helmed the subsequent analysis of the signal for Breakthrough Listen and is the lead author on an upcoming paper detailing that work, which will be published in early 2021. Soon, the team began calling the signal by a more formal name: BLC1, for “Breakthrough Listen Candidate 1.”

The data so far does not suggest this signal was produced by an alien technology. Instead, it likely is a spurious signal from some natural or human source, picked up by accident, as was the SETI “Wow” signal that for years puzzled astronomers until they traced it to a comet.

However, as they do not yet have an explanation, it is a mystery of some importance.

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Subaru Telescope photographs Hayabusa-2’s next target asteroid

2:09 pm

In order to better constrain its orbit, the Subaru Telescope in Hawaii has obtained new photographs of Hayabusa-2’s next target asteroid, 100-foot-wide 1998 KY26.

This asteroid is predicted to approach to within 0.47 AU of Earth in mid to late December 2020, giving us a rare opportunity that comes only once every three and a half years. However, the diameter of 1998 KY26 is estimated to be no more than 30 meters, and thus its brightness is so dim that ground-based observations of the asteroid are difficult without a very large telescope.

The observations with the Subaru Telescope were conducted upon the request of the Institute for Space and Astronautical Science (ISAS), JAXA. And as a result, 1998 KY26 was photographed in the direction of the constellation Gemini as a 25.4-magnitude point of light with a measurement uncertainty of 0.7 mag. The positional data collected during these observations will be used to improve the accuracy of the orbital elements of the asteroid. Similar observations were conducted with the Very Large Telescope (VLT) of the European Southern Observatory (ESO).

If all goes right Hayabusa-2 will rendezvous with 1998 KY26 in the summer of 2031.

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Astronomers detect radio signal from an exoplanet’s magnetic field

5:10 pm

The uncertainty of science: Astronomers using a Netherlands telescope have detected a radio signal coming from an exoplanet 51 light years away that likely comes from the planet’s magnetic field.

The new research actually began at Jupiter; the researchers had previously studied that planet’s radio emissions and then tweaked those measurements to reflect the effect they expected closeness to the host star and distance from Earth would have had on their observations of an exoplanet.

Then, the scientists consulted observations made in 2016 and 2017 by the Low Frequency Array (LOFAR) in the Netherlands. In addition to the potential signal from Tau Boötes b, the researchers also report that they may have picked up a signal from the star Upsilon Andromedae or its planet, but that detection was even fainter than the one from Tau Boötes b.

Obviously, there are many uncertainties with this data. However, if scientists can begin to measure and characterize the magnetic field of exoplanets it will give them an important new data point for studying them.

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Dark storm on Neptune changes direction unexpectedly

8:35 am

Dark storm on Neptune
Click for full image.

Using the Hubble Space Telescope, astronomers have found that a dark storm discovered on Neptune in 2018 has been drifting across the gas giant in unexpected ways.

The storm, which is wider than the Atlantic Ocean, was born in the planet’s northern hemisphere and discovered by Hubble in 2018. Observations a year later showed that it began drifting southward toward the equator, where such storms are expected to vanish from sight. To the surprise of observers, Hubble spotted the vortex change direction by August 2020, doubling back to the north. Though Hubble has tracked similar dark spots over the past 30 years, this unpredictable atmospheric behavior is something new to see.

Equally as puzzling, the storm was not alone. Hubble spotted another, smaller dark spot in January this year that temporarily appeared near its larger cousin. It might possibly have been a piece of the giant vortex that broke off, drifted away, and then disappeared in subsequent observations.

The photo to the right, cropped and reduced to post here, shows both storms. The smaller dark spot can be seen faintly to the right of the larger storm.

Since Hubble has been observing Neptune in 1993 it has seen four such storms, all of which have faded away after about two Earth years. What causes the storms as well as their motions in Neptune’s atmosphere remains unknown, and any theories posited (such as those noted at the link) are highly unreliable, considering the paucity of data we have about Neptune’s atmosphere and the meteorology of such gas giants.

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New data confirms and localizes uplifted lunar dust as seen by Apollo astronauts

1:11 pm

The uncertainty of science: In a paper released today, scientists reveal the detection of electrostatic dust events on the Moon similar to those observed by Apollo astronauts, and find that these events might not be global but instead confined to craters during twilight. From the abstract:

Lunar horizon glows observed by the Apollo missions suggested a dense dust exosphere near the lunar terminator. But later missions failed to see such a high‐density dust exosphere. Why the Apollo missions could observe so large number of dust grains remains a mystery. For the first time, we report five dust enhancement events observed by the Lunar Dust Experiment on board Lunar Atmosphere and Dust Environment Explorer [LADEE] mission, which happen near a twilight crater with dust densities comparable to the Apollo measurements. Moreover, the dust densities are larger on the downstream side of the crater and favor a higher solar wind temperature, consistent with an electrostatic dust lofting from the negatively charged crater floor. We also check the Apollo observations and find similar twilight craters, suggesting that the so‐called dust exosphere is not a global phenomenon but just a local electrified dust fountain near twilight craters.

The dust clouds the astronauts thought they saw near the horizon have been theorized to be dust uplifted by static electricity. However, all later missions had so far failed to detect this phenomenon, until now. That the result also pinpoints the location and ties it to twilight is important for future missions to the Moon. Astronauts can thus minimize any damage by this dust by shutting down operations during lunar twilight periods.

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Starlink dark coating reduces reflectivity by half

9:23 am

Astronomers in Japan have now confirmed that the dark coating SpaceX has been putting on its more recent Starlink satellites has successfully reduced their reflectivity by half.

They looked at the satellites across a range of wavelengths.

Observations conducted from April to June 2020 revealed for the first time in the world that artificial satellites, whether coated or not, are more visible at longer wavelengths, and that the black coating can halve the level of surface reflectivity of satellites. Such surface treatment is expected to reduce the negative impacts on astronomical observations.

Knowing this detail will allow commercial satellite companies such as SpaceX to further refine their coatings to better hide their satellites from ground-based telescopes.

While good news, it doesn’t change the fundamental lesson that astronomers need to learn. They must move their telescopes off the Earth and into space. In the long run ground-based astronomy is a dead-end.

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Hubble captures 20-year fading of planetary nebula

9:10 am

The fading of the Stingray Nebula
Click for full image.

Astronomers using the Hubble Space Telescope have now tracked the spectacular fading of the Stingray Nebula, which when it was discovered in the mid-1990s was labeled the youngest such object ever found.

Astronomers have caught a rare look at a rapidly fading shroud of gas around an aging star. Archival data from NASA’s Hubble Space Telescope reveal that the nebula Hen 3-1357, nicknamed the Stingray nebula, has faded precipitously over just the past two decades. Witnessing such a swift rate of change in a planetary nebula is exceeding rare, say researchers.

Images captured by Hubble in 2016, when compared to Hubble images taken in 1996, show a nebula that has drastically dimmed in brightness and changed shape. Bright blue fluorescent tendrils and filaments of gas toward the center of the nebula have all but disappeared, and the wavy edges that earned this nebula its aquatic-themed name are virtually gone. The young nebula no longer pops against the black velvet background of the vast universe.

Astronomers have found that the central star had been heating precipitiously in the late 20th century, from 40K to 108K degrees Fahrenheit. Since then it has begun to cool. They think that flash of heat, caused by what they think was short period of helium fusion, caused the planetary nebula to brighten, and now fade.

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First sunspot image from Inouye Solar Telescope

8:42 am

Sunspot image taken by Inouye Solar Telescope
Click for full image.

The science team for the new Inouye Solar Telescope, now in the final phase of construction, has released the telescope’s first high resolution sunspot image.

The image is to the right, reduced to post here, and was taken almost a year ago, on January 28, 2020.

“The sunspot image achieves a spatial resolution about 2.5 times higher than ever previously achieved, showing magnetic structures as small as 20 kilometers on the surface of the sun,” said [Dr. Thomas Rimmele, the associate director at NSF’s National Solar Observatory (NSO)].

The image reveals striking details of the sunspot’s structure as seen at the Sun’s surface. The streaky appearance of hot and cool gas spidering out from the darker center is the result of sculpting by a convergence of intense magnetic fields and hot gasses boiling up from below.

…This sunspot image, measuring about 10,000 miles across, is just a tiny part of the Sun. However, the sunspot is large enough that Earth could comfortably fit inside.

The start of official telescope operations is set to begin in ’21, and had been delayed because of the Wuhan flu panic. Construction had begun in ’13.

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New Gaia data release tracks distance and motion of 1.8 billion stars

10:49 am

The European Space Agency (ESA) today released the third round of data from its Gaia satellite, designed to measure precisely the distance and motion of billions of nearby stars.

Gaia EDR3 contains detailed information on more than 1.8 billion sources, detected by the Gaia spacecraft. This represents an increase of more than 100 million sources over the previous data release (Gaia DR2), which was made public in April 2018. Gaia EDR3 also contains colour information for around 1.5 billion sources, an increase of about 200 million sources over Gaia DR2. As well as including more sources, the general accuracy and precision of the measurements has also improved.

This release also included the following discoveries:

  • The Milky Way’s outer regions beyond the Sun contain two populations of stars, one slowly dropping towards the galaxy’s plane, the second flying away quickly.
  • The first precise measure of the solar system’s orbit in the Milky Way
  • A more complete census of all stars within 100 parsecs of the Sun
  • A better map of the interaction between the Large Magellanic Cloud and the Milky Way, which also showed that the cloud does have a spiral structure

This precise data will take decades to digest, as past research has been based on only rough distance and motion estimates. Having precise data will change our approximation of each object’s brightness, which will also change much of what we assume about it.

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Arecibo’s suspended instrument platform has collapsed onto dish

8:59 am

The suspended 900-ton instrument panel of the Arecibo Observatory in Puerto Rico collapsed early today, crashing down onto the radio telescope’s dish.

[Ramon Lugo, director of the Florida Space Institute at the University of Central Florida] says no one was near the dish when the platform fell. But he did not have all the details on how the structure came down. He believes it was because of a failure of one of the remaining cables connecting the platform to one of three support towers. These cables were carrying extra stress following the two previous failures. And since the Thanksgiving holiday, Lugo says, wires were breaking in these remaining cables at a rate of about one a day. He says he told NSF the structure only had a week or two remaining before it would collapse.

They plan on figuring out exactly what caused the collapse, but that is only to facilitate the planned decommissioning and removal of the telescope.

To me, this is another indicator of the arriving dark age. Earlier American generations would not only have never allowed this facility to fall into such disrepair, they would have never considered dismantling it. Instead, they would be planning how to make it bigger and better. Not today.

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Orbit of pristine comet in outer solar system is shifting inward

10:43 am

The orbit of a pristine comet that until now has kept it in the outer solar system, where it never got warm enough shed any material, is now shifting inward to join what is dubbed the Jupiter-family of comets, whose orbits are generally within that of Jupiter.

Although it has likely lost some supervolatile ices such as carbon dioxide ice (also known as dry ice) in the outer solar system beyond Jupiter, it is unlikely to have ever been in the inner solar system (where Earth, the other rocky planets, and [Jupiter-family comets] orbit), which is warm enough for water ice to sublime (‘evaporate’ from solid to gas),” Steckloff said. “This means that [Comet 2019] LD2 is a pristine comet, and presents a unique opportunity to observe how pristine [Jupiter-family comets] behave as their water ice begins to sublime for the first time and drive comet activity. Moreover, this transition is likely to finish in only 40 years from now, which is a blink of an eye for astronomy. This means that people alive today will be able to follow this object all the way through its transition into the [Jupiter-family] population.”

In 2019, when 2019 L2 was first identified, it was thought to be an asteroid that had suddenly become active, like a comet. Astronomers soon realized this was a mistake, that it was a comet whose orbit was being changed by its interaction with Jupiter.

The new data refines this conclusion, and confirms that observations of 2019 L2 will provide a lot of information about the make-up of the early solar system. More important, the comet’s orbit will allow for many observations, over a long period of time, unlike most comets that zip around the Sun in a year or so and then are gone.

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New data makes past nova too bright, but not bright enough to be supernova

9:21 am

The uncertainty of science: Astronomers, using new data from the Gemini North ground-based telescope, have found that a star that brightened in 1670 and was labeled a nova is much farther away than previously thought, which means that 1670 eruption was far too powerful for a nova, but not powerful enough to make it a supernova.

By measuring both the speed of the nebula’s expansion and how much the outermost wisps had moved during the last ten years, and accounting for the tilt of the nebula on the night sky, which had been estimated earlier by others, the team determined that CK Vulpeculae lies approximately 10,000 light-years distant from the Sun — about five times as far away as previously thought. That implies that the 1670 explosion was far brighter, releasing roughly 25 times more energy than previously estimated [4]. This much larger estimate of the amount of energy released means that whatever event caused the sudden appearance of CK Vulpeculae in 1670 was far more violent than a simple nova.

“In terms of energy released, our finding places CK Vulpeculae roughly midway between a nova and a supernova,” commented Evans. “[T]he cause — or causes — of the outbursts of this intermediate class of objects remain unknown. I think we all know what CK Vulpeculae isn’t, but no one knows what it is.”

Recent research has also suggested that the cause of the eruption was not from the interaction of a binary system with one normal star and a white dwarf, as believed for decades, but possibly a binary system with a brown dwarf, or a red giant star, or two normal stars. All are remain possible, none however have been confirmed.

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Arecibo Observatory to be shut down permanently

10:27 am

The arriving dark age: Due to the extent of its recent cable failures and the risks they pose to works, the National Science Foundation (NSF) has decided to shuttered and dismantle it permanently.

Ralph Gaume, director of NSF’s astronomy division, said at the briefing the agency wants to preserve other instruments at the site, as well as the visitor and outreach center. But they are under threat if the telescope structure collapses. That would bring the 900-ton instrument platform, suspended 137 meters above the 305-meter wide dish, crashing down. Flailing cables could damage other buildings on the site, as could the three support towers if they fell, too. “There is a serious risk of an unexpected and uncontrolled collapse,” Gaume said. “A controlled decommissioning gives us the opportunity to preserve valuable assets that the observatory has.”

Over the next few weeks, engineering firms will develop a plan for a controlled dismantling. It may involve releasing the platform from its cables explosively and letting it fall.

The radio telescope was built in the early 1960s, and for many years was the world’s largest single dish radio telescope. It has struggled however in recent years with both financial and infrastructure problems, the latter initially caused by Hurricane Maria in 2017.

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New model suggests ringed nebula caused by star merger

10:29 am

The Blue Ring Nebula
Click for full image.

Based on a new theoretical model, astronomers now believe that the Blue Ring Nebula, a planetary nebula discovered in 2004 by the Galaxy Evolution Explorer (GALEX), was the result of the merger of two stars that only occurred a few thousand years earlier.

The image to the right, cropped, reduced, and annotated to post here, shows the original GALEX image on top, with a model to illustrate the geometry. The nebula is shaped like an hour-glass, with the rings the wide parts at the top and bottom. We just happen to be looking at it along its axis.

A new study published online on Nov. 18 in the journal Nature may have cracked the case. By applying cutting-edge theoretical models to the slew of data that has been collected on this object, the authors posit the nebula – a cloud of gas in space – is likely composed of debris from two stars that collided and merged into a single star.

While merged star systems are thought to be fairly common, they are nearly impossible to study immediately after they form because they’re obscured by debris the collision kicks up. Once the debris has cleared – at least hundreds of thousands of years later – they’re challenging to identify because they resemble non-merged stars. The Blue Ring Nebula appears to be the missing link: Astronomers are seeing the star system only a few thousand years after the merger, when evidence of the union is still plentiful. It appears to be the first known example of a merged star system at this stage.

When the merger happened it caused the bi-polar jets that formed the hourglass shape.

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Venus results suggesting life downgraded

9:57 am

Surprise! Surprise! Further research and review of the recent results that said phosphine existed in Venus’s atmosphere — which for some immediately suggested the presence of life — has found that the phosphine probably doesn’t exist.

[A]lmost immediately, other astronomers began to criticize the results, with four independent studies pointing out questionable methods or failing to reproduce the results.

Now, after reanalyzing their data, the original proponents are downgrading their claims. Even the most favorable interpretation of their data now suggests phosphine levels are at least seven times lower than first reported, making it a much more tentative finding, the authors reported in a preprint posted on 17 November to arXiv.

Also, observations in other wavelengths detected no phosphine, even though it should have been there if the first study was correct. Furthermore, other scientists have noted that the spectrum features detected might not be caused by phosphine. The sulphur dioxide in Venus’s atmosphere could instead be their source.

Even if phosphine is eventually confirmed, that is not the discovery of life on Venus, as so many in the mainstream press claimed. As I noted when this result was first announced, phosphine isn’t life, it is merely a specific inanimate molecule. That on Earth it only exists in connection with life-processes means nothing. Venus is a very alien place, and there could be any number of inanimate chemical processes that we have no experience with or knowledge of that could produce it there. To claim its discovery suggests the existence of life, or even the possibility of life, is simply junk science.

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Arecibo’s status appears to be worsening

8:47 am

According to a new engineering report, the condition and status of the Arecibo Observatory’s main antenna, suspended by cables above its giant radio dish, appears very uncertain and to be worsening.

Preliminary analysis indicates the main cable, which failed on Nov. 6, should have easily handled the extra load based on design capacity. Engineers suspect it is likely that the second cable failed because it has degraded over time and has been carrying extra load since August. A final determination could not be made without retrieving and analyzing the second cable.

The engineering firms cannot verify the integrity of the other cables at this time supporting the 900-ton platform. Each of the structure’s remaining cables is now supporting more weight than before, increasing the likelihood of another cable failure, which would likely result in the collapse of the entire structure.

Other wire breaks on two of the remaining main cables have also been observed. [emphasis mine]

If the 900 ton antenna structure that the cables hold up should fall, it will do significant damage to the disk, and will also likely make the cost of repairing the radio telescope prohibitive.

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Hubble sees too much infrared energy from gamma ray burst

9:09 am

The uncertainty of science: During a short gamma ray burst (GRB) that was observed in a distant galaxy on May, astronomers were baffled when measurements from the Hubble Space Telescope detected ten times more near infrared energy that they predict from this type of GRB.

GRBs fall into two classes. First there are the long bursts, which are thought to form from the collapse of a massive star into a black hole, resulting in a powerful supernova and GRB. Second there are the short bursts, which scientists think occur when two neutron stars merge.

The problem with this GRB is that though it was short and somewhat similar to other short GRBs across most wavelengths, in the near infrared Hubble detected far too much energy.

“These observations do not fit traditional explanations for short gamma-ray bursts,” said study leader Wen-fai Fong of Northwestern University in Evanston, Illinois.

…Fong and her team have discussed several possibilities to explain the unusual brightness that Hubble saw. While most short gamma-ray bursts probably result in a black hole, the two neutron stars that merged in this case may have combined to form a magnetar, a supermassive neutron star with a very powerful magnetic field. “You basically have these magnetic field lines that are anchored to the star that are whipping around at about a thousand times a second, and this produces a magnetized wind,” explained Laskar. “These spinning field lines extract the rotational energy of the neutron star formed in the merger, and deposit that energy into the ejecta from the blast, causing the material to glow even brighter.”

What is intriguing about their theory is that this merger of two neutron stars simply resulted in a larger neutron star, not a black hole. This new neutron star was also a magnetar and pulsar, but unlike a black hole, it was a still-visible physical object. And yet its creation in this GRB produced more energy.

When GRBs were first discovered, I was always puzzled why so many astronomers seemed to insist there must be a single explanation for them. With time, when two classes of GRBs were discovered, this assumption was then replaced with the equally puzzling insistence that only two types of events explained them.

It seemed to me that that such explosions had too many potential variables, and could easily have a wide range of causes, though all related to the destruction or merger of massive stars. As the data continues to accumulate this now appears increasingly the case.

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Meteorite stolen five years ago from Australian museum recovered

8:45 am

A meteorite that was stolen five years ago from a small Australian museum, only two weeks after it was donated to that museum, was recovered by police two days ago.

While the police have returned the meteorite, they have not yet revealed much else.

On Saturday, Queensland Police executed a search warrant at a Cairns address and recovered the space rock, valued at more than $16,000.

Investigations are underway into the incident, and no charges have been laid, but the sisters are pleased the meteorite is back in their possession.

…Police investigating the incident said they were looking into a number of leads relating to the theft. “I believe it definitely has a story to tell,” Senior Constable Heidi Marek said. “I’ll leave it up to detectives to uncover that story but hopefully we’re able to reveal a bit of information down the track.”

That no charges were file is most puzzling. I hope the full story is soon revealed.

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Second cable failure further disables Arecibo radio telescope

8:28 am

A second cable at the Arecibo Observatory in Puerto Rico has broken, further disabling the radio telescope from operation.

A main cable that supports the Arecibo Observatory broke Friday at 7:39 p.m. Puerto Rico time.

Unlike the auxiliary cable that failed at the same facility on Aug. 10, this main cable did not slip out of its socket. It broke and fell onto the reflector dish below, causing additional damage to the dish and other nearby cables. Both cables were connected to the same support tower. No one was hurt, and engineers are already working to determine the best way to stabilize the structure.

The telescope has been badly crippled since the first cable failure in August.

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First fast radio burst detected in Milky Way

10:57 am

Astronomers using both space- and ground-based telescopes have detected for the first time a fast radio burst occurring inside the Milky Way, finding that it came from a magnetar, a pulsar with an extremely powerful magnetic field.

The radio component was discovered by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a radio telescope located at Dominion Radio Astrophysical Observatory in British Columbia and led by McGill University in Montreal, the University of British Columbia, and the University of Toronto.

A NASA-funded project called Survey for Transient Astronomical Radio Emission 2 (STARE2) also detected the radio burst seen by CHIME. Consisting of a trio of detectors in California and Utah and operated by Caltech and NASA’s Jet Propulsion Laboratory in Southern California, STARE 2 is led by Bochenek, Shri Kulkarni at Caltech, and Konstantin Belov at JPL. They determined the burst’s energy was comparable to FRBs.

By the time these bursts occurred, astronomers had already been monitoring their source for more than half a day.

Late on April 27, NASA’s Neil Gehrels Swift Observatory spotted a new round of activity from a magnetar called SGR 1935+2154 (SGR 1935 for short) located in the constellation Vulpecula. It was the object’s most prolific flare-up yet – a storm of rapid-fire X-ray bursts, each lasting less than a second. The storm, which raged for hours, was picked up at various times by Swift, NASA’s Fermi Gamma-ray Space Telescope, and NASA’s Neutron star Interior Composition Explorer (NICER), an X-ray telescope mounted on the International Space Station.

Later observations detected X-rays from the same source. While this does not prove that all fast radio bursts come from magnetars, it does prove that at least some do.

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