The interstellar rogue comet Borisov is stranger than we thought

As for tourist destinations, our solar system appears to be fairly low on the universe’s list of the best places to visit: Astronomers have only spotted two interstellar visitors passing through our neighborhood. Even though our visitor count is still low, those two bums have given us an insight into the truly unusual bums that traverse the cosmos. First — Oumuamua — I was so strange scientists suggested it might even be an alien probe.

The second visitor, Rebel Kite 2I / Borisov, seemed pretty normal compared – but a new analysis shows that our second interstellar visitor is also quite strange.

Two studies, published in the journal Nature Astronomy on Monday, examined Borisov using the Hubble Space Telescope and the Atacama Large Millimeter / submillimeter Array (ALMA) in northern Chile. Astronomers were particularly fortunate with Borisov’s observations because, unlike ‘Oumuamua, he was seen at the customs line on my way in to our solar system, giving them the opportunity to observe it.

Hubble and ALMA targeted Borisov in December and January as he moved through our corner of space just outside of Mars orbit. As he got closer to the sun, Borisov warmed up, causing him to expel some of the gases trapped inside. This gave researchers with Hubble and ALMA the opportunity to study different wavelengths of light emitted by the interstellar visitor and determine what gases it contains.

“This is the first time we have looked inside a comet from outside our solar system,” Martin Cordiner, an astrochemist at NASA’s Goddard Flight Center and first author of the article, said in a statement. “It is dramatically different from most of the other comets we’ve seen before.”

Both studies show that Borisov is extremely rich in carbon monoxide. It’s not uncommon to find carbon monoxide in a comet, but the levels observed by Hubble and ALMA are off the charts, measuring roughly three times more than comets in our home solar system. Because carbon monoxide only freezes at extremely cold temperatures, research teams suggest that it probably formed on the dark, outer edges of a distant star system before being thrown at us.

Borisov’s story is a bit bleak, even for a space rock. In the article by Dennis Bodewits, professor of physics at Auburn University, and his colleagues, the authors speculate that Borisov may have started his life around an M-type star, one of the most common types of stars in our forest neck. . The team suggests that a giant planet orbiting such a star could have launched Borisov and launched it into the depths of space. From there, he wandered, lonely and insanely cold, for millions of years until physics and fate brought him close enough to our sun to warm and burst with life.

As it flows through our region of space now, Borisov seems to be falling apart like a biscuit dipped in tea. Recent images of Borisov showed that it broke and a small fragment was ejected into space. A more recent notice in The Astronomer’s Telegram shows that the child fragment is no longer visible. Unfortunately, the coronavirus pandemic it has prevented a more concerted look at the tourist because many of the main observatories that can still see the comet here on Earth have closed.

Hubble should be able to track Borisov until 2021, but ground-based telescopes like ALMA will likely lose sight of it in the coming months. While the small window of opportunity to learn more about Borisov is closing, there is no doubt that our solar system will be hosting a third dishonest tourist sometime in the near future; here we hope it is just as strange.

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