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Interstellar Comet 2I/Borisov Formed in a Very Cold Environment – Universe Today

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In the summer of 2019, a team of astronomers from NASA, the ESA, and the International Scientific Optical Network (ISON) announced the detection of the comet 2I/Borisov. This comet was the only second interstellar visitor observed passed through our Solar System, coming on the heels of the mysterious ‘Oumuamua. For this reason, astronomers from all over the world watched this comet intently as it made its closest pass to the Sun.

One such group, led by Martin Cordiner and Stefanie Milam of NASA’s Goddard Space Flight Center, observed 2I/Borisov using the ESO’s Atacama Large Millimeter/submillimeter Array (ALMA) in the Chilean Andes. This allowed them to observe the gases 2I/Borisov released as it moved closer to our Sun, thus providing the first-ever chemical composition readings of an interstellar object.

Astronomers are naturally interested in the study of comets because they are essentially material left over from the formation of the Solar System. In addition, they spend most of their lives at large distances from any star and in very cold environments. The majority of comets observed in the Solar System, for example, originated in the Kuiper Belt or the Oort Cloud, depending on whether they are short-period or long-period comets.

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In addition, the interior composition of comets has not changed significantly since the formation of the Solar System. Therefore, the study of their interiors can tell scientists a great deal about the processes that occurred during their birth in protoplanetary disks. This becomes possible as comets draw closer to their suns and their ices begin to sublimate (a process known as “outgassing.”)

Interstellar comets are of particular interest to astronomers because they can tell us a great deal about the formation and evolution of star systems other than our own. When they observed 2I/Borisov, the team detected two types of gas molecules being ejected from the comet: hydrogen cyanide (CHN) and carbon monoxide (CO). The study that describes these findings recently appeared in the journal Nature.

While the team expected to see the former, which is present in 2I/Borisov in similar concentrations to what has been observed in Solar System comets, they were surprised to see large amounts of CO as well. In fact, the CO concentrations were estimated to be 9 to 26 times higher than the average Solar System comet or any comet detected within 2 AU of the Sun (twice the distance between the Earth and the Sun.)

“The comet must have formed from material very rich in CO ice, which is only present at the lowest temperatures found in space, below -420 degrees Fahrenheit (-250 degrees Celsius),” said planetary scientist Stefanie Milam in a recent NRAO press release.

ALMA images showing hydrogen cyanide (HCN) and Carbon monoxide (CO) gas being released from 2I/Borisov. Credit: ALMA (ESO/NAOJ/NRAO), M. Cordiner & S. Milam; NRAO/AUI/NSF, S. Dagnello

While CO is one of the most plentiful molecules in space and is found inside most comets, there are typically huge variation in terms of its concentration in comets – for reasons which remain unknown. This may be a result of where they formed in the Solar System and/or how often a comet gets closer to the Sun and loses some of its more-easily evaporated ices. As astrochemist Martin Cordiner explained:

“This is the first time we’ve ever looked inside a comet from outside our solar system, and it is dramatically different from most other comets we’ve seen before… If the gases we observed reflect the composition of 2I/Borisov’s birthplace, then it shows that it may have formed in a different way than our own solar system comets, in an extremely cold, outer region of a distant planetary system.”

In all previous cases where ALMA was used to study protoplanetary disks, those disks were found around Sun-like stars. At the same time, many disks extended far beyond where comets in the Solar System are believed to have formed and contained large amounts of extremely cold gas and dust. While the team can only speculate at this point, they believe it is possible that 2I/Borisov came from one of these larger disks.

Given the speed with which it traveled through our Solar System (33 km/s; 21 mps), astronomers suspect that 2I/Borisov was likely to have been kicked out of its host system by gravitational interaction – possibly from a passing star or a giant planet. After that, it is thought to have spent millions or billions of years travelling through the extreme cold of interstellar space before arriving in our Solar System.

Labeled version of four of the twenty disks that comprise ALMA’s highest resolution survey of nearby protoplanetary disks. Credit: ALMA (ESO/NAOJ/NRAO) S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello

2I/Borisov was discovered on August 30th, 2019 by amateur astronomer Gennady Borisov, who it was named in honor of. The only other insteallr object observed – 1I/’Oumuamua – was already on its way out of the Solar System when it was first detected, which made it very difficult to study the object and determine if it was an asteroid, a comet, a fragment of a comet, or something else entirely (like an alien spacecraft or derelict).

In 2I/Borisov’s case, the presence of an active gas and dust coma surrounding it confirmed that it was the first known interstellar comet to ever be observed. The fact that it’s composition is unlike that of comets observed in the Solar System only makes it more appealing for researchers, and is an invitation to find more interstellar comets. As Milam put it:

“2I/Borisov gave us the first glimpse into the chemistry that shaped another planetary system. But only when we can compare the object to other interstellar comets, will we learn whether 2I/Borisov is a special case, or if every interstellar object has unusually high levels of CO.”

In addition to the many ground-based and space-based telescopes that will be on the lookout for interstellar asteroids and comets in the future, there is also compelling evidence that many interstellar objects that arrived in the past ended up staying here. There are even proposals in place to send a spacecraft to rendezvous with an interstellar object in the future, like the ESA’s Comet Interceptor.

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There’s no telling when the next interstellar comet or asteroid will pass through our Solar System, or whether or not we will be able to study it up-close using a spacecraft. One thing that is certain is that any future visitors will offer astronomers the opportunity to learn more about other star systems, like their compositions and how planets form within them.

The international team behind this study included members from the Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique (LESIA), the STAR Institute, the National Radio Astronomy Observatory (NRAO), the Institut de RAdioastronomie Millimétrique (IRAM), multiple universities, the NASA Jet Propulsion Laboratory and NASA HQ.

Since the team led by Cordiner and Milam made their observations, 2I/Borisov appears to have split into two objects (aka. “calving.”) This occurred in late March as the comet was making its way back into interstellar space. The venerable Hubble was able to catch a final glimpse of “Little Boris and Big Boris” as they departed our Solar System, perhaps never to be seen again.

Further Reading: NRAO, Nature

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This is an Actual Image of a Planet-Forming Disc in a Distant Star System – Universe Today

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In 2017, astronomers used ALMA (Atacama Large Millimeter/sub-millimeter Array) to look at the star AB Aurigae. It’s a type of young star called a Herbig Ae star, and it’s less then 10 million years old. At that time, they found a dusty protoplanetary disk there, with tell-tale gaps indicating spiral arms.

Now they’ve taken another look, and found a very young planet forming there.

Young Herbig Ae stars like AB Aurigae are of great interest to astronomers. They’re so young they’re not main sequence stars yet, and they’re still surrounded by their circumstellar disk of gas and dust. And out of that gas and dust, young planets are forming.

The disk around AB Aurigae, which is over 500 light years away, has spiral arms that meet in a knot. Scientists believe that the knot is the precise point where a young planet is forming. A new study used the SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) instrument on the Very Large Telescope (VLT) to take a closer look at AB Aurigae and the planets developing inside its disk.

The new study is titled “Possible evidence of ongoing planet formation in AB Aurigae.” Lead author of the study is Anthony Boccaletti from the Observatoire de Paris, PSL University, France. The paper is published in the journal Astronomy and Astrophysics.

“Thousands of exoplanets have been identified so far, but little is known about how they form,” said lead author Boccaletti in a press release. Observing young, still-forming planets is a big deal in astronomy right now, but it’s difficult. The circumstellar disk around the star is difficult to see into, and even our best technology is barely up to the task.

Artist’s impression of circumstellar disk of debris around a distant star. These disk are common around younger stars, and they’re difficult to see into. Credit: NASA/JPL

The SPHERE instrument was critical to this work. It’s an advanced adaptive optics system, combined with a coronoagraph. It was developed to advance the study of exoplanets, with low-resolution spectrographic and polarimetric images. It images in both optical and infrared light. SPHERE allowed the team behind this study to focus on the earliest stages of planetary formation.

“We need to observe very young systems to really capture the moment when planets form,” said Boccaletti. That twisted knot where the spiral arms of AB Aurigae’s circumstellar disk meet is as close as we’ve come to capturing that moment.

These spirals indicate the birth of a baby planet. That’s because the planet’s mass has an effect on the less dense gas and dust in the disk. Essentially, the planet kicks the material in the disk, creating a visible wave: the spirals.

“The twist of the spiral is perfectly reproduced with a planet-driven density wave model when projection effects are accounted for.”

From the Study “Possible evidence of ongoing planet formation in AB Aurigae.”

According to Emmanuel Di Folco of the Astrophysics Laboratory of Bordeaux (LAB), France, who took part in this study, the young planets create “disturbances in the disc in the form of a wave, somewhat like the wake of a boat on a lake.” And as the young planet rotates around the central star, those disturbances become spiral arms.

The images of the AB Aurigae system showing the disc around it. The image on the right is a zoomed-in version of the area indicated by a red square on the image on the left. It shows the inner region of the disc, including the very-bright-yellow ‘twist’ (circled in white) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The blue circle represents the size of the orbit of Neptune. The images were obtained with the SPHERE instrument on ESO’s Very Large Telescope in polarised light. Image Credit: ESO/Boccaletti et al, 2020
The images of the AB Aurigae system showing the disc around it. The image on the right is a zoomed-in version of the area indicated by a red square on the image on the left. It shows the inner region of the disc, including the very-bright-yellow ‘twist’ (circled in white) that scientists believe marks the spot where a planet is forming. This twist lies at about the same distance from the AB Aurigae star as Neptune from the Sun. The blue circle represents the size of the orbit of Neptune. The images were obtained with the SPHERE instrument on ESO’s Very Large Telescope in polarised light. Image Credit: ESO/Boccaletti et al, 2020

In their paper the authors caution us that we’re still learning what goes on inside these circumstellar veils that surround young stars. We’re still in the early days of seeing into those structures, and they aren’t certain that this twist is a planet.

“SPHERE has delivered the deepest images ever obtained for AB Aur in scattered light. Among the many structures that are yet to be understood, we identified not only the inner spiral arms, but we also resolved a feature in the form of a twist in the eastern spiral at a separation of about 30 au.”

Are they certain it’s a planet? Not exactly, but the twist feature matches modelling. “The twist of the spiral is perfectly reproduced with a planet-driven density wave model when projection effects are accounted for,” the authors write.

Initial observations of AB Aurigae made with ALMA, but without SPHERE, showed the pair of spiral arms. But ALMA alone didn’t reveal as much information. It revealed tantalizing hints, though, that planets were forming.

ALMA image of the dust ring (red) and gaseous spirals (blue) of the circumstellar disk AB Aurigae reveal gaseous spiral arms inside a wide dust gap, providing a hint of planet formation. By ALMA (ESO/NAOJ/NRAO)/Tang et al. – https://www.almaobservatory.org/en/press-release/astronomers-found-spirals-inside-a-dust-gap-of-a-young-star-forming-disk/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=87359440

Though ALMA is a powerful tool, SPHERE is even more powerful. It can see the very faint light from dust grains, and emissions that come from the inner disk. Astronomers were able to see the details in the spirals, and the “twist” at their center.

“The twist is expected from some theoretical models of planet formation,” says co-author Anne Dutrey, also at LAB. “It corresponds to the connection of two spirals  — one winding inwards of the planet’s orbit, the other expanding outwards — which join at the planet location. They allow gas and dust from the disc to accrete onto the forming planet and make it grow.”

The disk is an elaborate structure, and astronomers observed many other structures within it. Two of them were of particular interest, marked f1 and f2 in this image. Both of these are SPHERE images, each one with a different intensity threshold. Image Credit: Boccaletti et al, 2020.
The disk is an elaborate structure, and astronomers observed many other structures within it. Two of them were of particular interest, marked f1 and f2 in this image. Both of these are SPHERE images, each one with a different intensity threshold. Image Credit: Boccaletti et al, 2020.

There’s ample theory to support the birth of planets at the twist point. “In the early stage of planet formation, hydrodynamical simulations indicate that the accretion process generates at the planet location an inner and outer spiral pattern due to Lindblad resonances induced by disk-planet interactions,” the team writes.

But the observational evidence to back it all up has been difficult to come by. This study presents some of the best observations yet that back the theory up.

In their conclusion, the authors write “…the SPHERE observations of AB Aur in scattered light combined to the ALMA data in the thermal regime provide strong evidence that we are actually witnessing ongoing planet formation revealed by its associated spiral arms.”

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But it’s not proven yet. “Further observations would be required to confirm this result and to derive better mass estimates for potential planets in this location.”

Those further observations might not be too far in the future. The ESO’s Extremely Large Telescope (ELT) should see first light in 2025. With a 39 meter mirror, the ELT will be an enormous boost to our astronomical observing power.

“We should be able to see directly and more precisely how the dynamics of the gas contributes to the formation of planets,” lead author Boccaletti concluded.

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Stormy weather puts damper on SpaceX’s 1st astronaut launch – 95.7 News

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CAPE CANAVERAL, Fla. — Stormy weather is threatening to delay SpaceX’s first astronaut launch.

A SpaceX rocket is scheduled to blast off Wednesday afternoon from Kennedy Space Center, carrying a Dragon capsule with NASA astronauts Doug Hurley and Bob Behnken to the International Space Station. It will be the first time astronauts launch from Florida in nine years and a first for a private company.

The manager of NASA’s commercial crew program, Kathy Lueders, said everything was progressing well — at least on the ground.

“Now the only thing we need to do is figure out how to control the weather,” she said Monday evening as rain continued to drench the area. “We’re continuing to be vigilant and careful and make sure we do this right.”

Forecasters put the odds of acceptable launch weather at 40%. But that doesn’t include the conditions all the way up the U.S. and Canadian coasts and across the sea to Ireland — a complicated mix of measurements unique to the Dragon crew capsule.

The Dragon’s emergency escape system can kick in, if necessary, all the way to orbit. If that happens, the capsule will need relatively calm wind and seas in which to splash down.

SpaceX will have at least two recovery ships deployed off Florida, and NASA will have two military cargo planes ready to take off. Additional planes will be stationed in New York and England to assist with a potential water rescue, according to Lueders.

Hans Koenigsmann, a vice-president for SpaceX, said the launch control team will incorporate global weather patterns and models to determine whether it’s safe to launch.

“If the weather gods are working with us,” he said, liftoff will occur at 4:33 p.m. SpaceX has a split-second launch window.

The good news is that the tropical weather headed toward Cape Canaveral should be gone in a couple days, with conditions also improving up the Eastern Seaboard later in the week.

If SpaceX doesn’t launch Wednesday, its next attempt would be Saturday.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

Marcia Dunn, The Associated Press

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Extremely rare 'cosmic ring of fire' discovered in the early universe – CNET

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The ring galaxy R5519 may have been created during a massive, catastrophic collision between two galaxies in the early universe.


James Josephides/Swinburne Astronomy Productions

A violent, catastrophic collision between two galaxies has given rise to an extremely rare ring galaxy, lurking some 11 billion light years from the Earth. The monstrous, donut-shaped galaxy is making stars in its huge ring at a rate 50 times faster than our home galaxy, earning it an ominous moniker Johnny and June Cash would surely dig: The cosmic “ring of fire.”

In a paper, published in the journal Nature Astronomy on Tuesday, an international team of scientists detail the ring galaxy R5519, discovered after scouring data from the Hubble Space telescope and the W.M. Keck observatory in Hawaii. Among almost 4,000 galaxies detected in the data sets, R5519 was one of the brightest and displayed a clear ring structure. So the team investigated further — and quickly realized they’d found something unusual. 

“It is very a curious object, one that we have never seen before,” says Tiantian Yuan, an astronomer at Swinburne University in Australia and first author on the study. “The gigantic hole in this galaxy was caused by a head-on collision with another galaxy.”  

Probing the features of R5519, Yuan and her team began picking up clues as to how it formed. They ruled out gravitational lensing or a galaxy merger for its unusual structure and nearby, they detected a companion galaxy — G5593. They suspect this cosmic neighbor is the “intruder” galaxy that may have collided with R5519 around 40 million years ago. 

The two galaxies must have smashed into each other pretty much head-on — a galactic bulls-eye — and it’s likely there was already a disk of stars present in R5519. As G5593 came swooping through the galaxy, it split the disk through the guts and a wave of stars expanded from the center, as seen in the GIF above.

“The collisional formation of ring galaxies requires a thin disk to be present in the ‘victim’ galaxy before the collision occurs,” said Kenneth Freeman, an astronomer at Australian National University and co-author on the paper, in a statement. 

If R5519 is caused by a huge collision, that would make it an extremely rare cosmic phenomena. Only one in every 10, 000 galaxies in the local universe are formed in such a way. Notably, the early universe was much more crowded so the belief was these kind of collisions may have been more common. Yuan suggests the data is telling a different story.

“Previously, people think we would find more of these collisional ring galaxies in the young universe, simply because there are more collisions back then,” she says. “We find that is not the case.”

There are still some “unsolved puzzles” about the ring of fire, Yuan says. “We do not know if this ring was a first ring after the collision or it was the second ring.” She’s obtained further data from W.M. Keck to resolve this issue.

Astronomers will have to gather more data to be certain the ring is caused by a collision, rather than through natural evolution. The authors of the paper write the imaging performed by NASA’s soon-to-be-launched (and recently-assembled) James Webb Space Telescope will be able to resolve any lingering questions. Yuan says she has already discovered another ring galaxy likely formed by a head-on collision — and this is a billion years older than the “ring of fire.”

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