A new study shows that the largest ever observed comet is active at close ranges on record

Comet Bernardinelli-Bernstein (BB), which is featured in this art exhibition because it may appear in the outer solar system, is estimated to be about 1,000 times the mass of a regular comet. The largest comet discovered in the modern era, it is one of the most distant comets found in a coma, which means the ice inside the comet evaporates and forms a blanket of dust and vapor around the comet’s core. Credit: NOIRLab/NSF/AURA/J. da Silva/Spaceengine

A new study by astronomers at the University of Maryland shows that Comet Bernardinelli-Bernstein (BB), the largest comet ever discovered, was active long before previously thought, meaning that the ice inside evaporated and formed a blanket of dust and vapor known as a coma. . Only one active comet has been observed far from the Sun, and it is much smaller than Comet BB.


The discovery will help astronomers determine what BB is made of and provide insight into the conditions during the formation of our solar system. The results have been published in Journal of Planetary Science On November 29, 2021.

“These observations push the distance of active comets further than we previously knew,” said Tony Farnam, a research scientist in UMD’s Department of Astronomy and lead author of the study.

know when comet Being active is key to understanding what it contains. Often called “dirty snowballs” or “dirty ice balls,” comets are clumps of dust and ice left over from the formation of the Solar System. As an orbiting comet approaches its closest point to the sun, its temperature rises and the ice begins to evaporate. The temperature at which evaporation must begin depends on the type of ice it contains (for example, water, carbon dioxide, carbon monoxide, or other frozen compound).

Scientists first discovered comet BB in June 2021 using data from the Dark Energy Survey, an international collaborative effort to survey the skies in the southern hemisphere. The survey captured the comet’s bright core, but did not have a high enough resolution to reveal the veil of dust and vapor that formed when the comet became active.

Comet BB, which is 100 kilometers wide, is the largest comet ever discovered, and is farther from the sun than the planet Uranus. Most comets are located about a kilometer or so away and closer to the Sun when they are detected. When Farnham heard about the discovery, he immediately wondered if images of Comet BB had been taken by the Transient Exoplanet Survey Satellite (TESS), which monitors one region of the sky for 28 days at a time. It is thought that a longer TESS exposure time could provide more detail.

Farnham and his colleagues collected thousands of images of Comet BB collected by TESS from 2018 to 2020. By stacking the images, Farnham was able to increase the contrast and obtain a clearer view of the comet. But because the comet is moving, it has to overlay the image so that Comet BB is aligned in each frame. This technique removes stray spots from individual shots while amplifying the comet’s image, allowing the researchers to see the hazy glow from the comet. land BB contour, proof BB has files come It’s active.

To make sure the coma wasn’t just blurring caused by image buildup, the team repeated this technique with images of inactive objects from the Kuiper Belt, a region much farther from the sun than Comet BB where the ice debris originated from. The solar system abounds. While these things appear pristine, without distortion, the researchers believe that the faint light around Comet BB is actually an active coma.

Comet BB’s size and distance from the Sun indicate that the vaporized ice that forms the coma is dominated by carbon monoxide. Since carbon monoxide can begin to evaporate up to five times farther from the sun than Comet BB was when it was discovered, it’s likely that BB was already active before it could be observed.

“We’re assuming that Comet BB is likely active beyond that, but we’ve never seen it before,” Farnham said. “What we don’t know yet is whether there is a stopping point where we can start seeing these objects in cold storage before they become active.”

According to Farnham, the ability to observe processes such as the formation of coma comets further than before opens exciting new doors for astronomers.

“This is just the beginning,” said Farnam. “TESS is looking at things that haven’t been detected, and that’s kind of a test case of what we can find. We have the ability to do a lot of things, just by looking at comets, going back in time. in the image and find it at a great distance from the Sun.”


The largest comet ever seen will approach Saturn in 2031


further information:

Tony L. Farnham et al., Early activity on comet C/2014 UN271 Bernardinelli-Bernstein as observed by TESS, Journal of Planetary Science (2021). DOI: 10.3847 / PSJ / ac323d

quote: New study shows largest ever observed comet active at close to record-breaking distance (2021, 29 November) Retrieved 29 November 2021 from https://phys.org/news/2021-11-largest-comet-near-record- distance .programming language

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