Astronomers found interesting signs of activity in Comet Bernardinelli-Bernstein. Credit: NOIRLab/NSF/AURA/J. da Silva/Spaceengine

Largest Comet Ever Found Shows Unexpected Signs of Activity

The comet's activity is associated with the sublimation of frozen carbon monoxide, which is continuous in time and is not the result of spontaneous outbreaks.

Astronomers using the TESS and NEOWISE space telescopes were able to determine the main parameters of the activity of the giant comet C / 2014 UN271 Bernardinelli-Bernstein from the Oort cloud. It is assumed that its coma consists of submillimeter-sized grains ejected from the surface of the nucleus during the sublimation of frozen carbon monoxide. 


Comet Bernardinelli-Bernstein

Comet Bernardinelli-Bernstein (C / 2014 UN271) was discovered this summer on June 19, 2021, in archival images of the DES (Dark Energy Survey) sky survey, taken between 2014 and 2018. Initially, scientists believed they had found a dwarf planet.

New observations of the object, carried out on June 22, 2021, using the 1-meter Sutherland telescope of the LCOGT ground network, showed that it is active and has a slightly asymmetric coma, which is typical for comets. At the time of the 2014 observations, UN271 was located at a distance of 20.18 astronomical units, the brightness was estimated at 19.8 magnitude, which is slightly higher than predicted.

Animation showing the movement of the comet in a month. Credit: Ben Montet / TESS
Animation showing the movement of the comet in a month. Credit: Ben Montet / TESS

Currently, C / 2014 UN271 is believed to be a unique small body in the solar system – a record-breaking giant comet moving from the inner edge of the Oort cloud towards the Sun, which in early 2031 will pass its next perihelion, located between the orbits of Saturn and Uranus.

What new information did astronomers find?

A group of astronomers led by Tony L. Farnham from the University of Maryland has published the results of an analysis of the TESS space telescope’s observations of the comet from 2018 to 2020.

Previously, TESS images have already helped to reveal the activity of the comet, but now scientists have studied the archival data in more detail in order to determine the properties of the Bernardinelli-Bernstein nucleus. The work also used data from the NEOWISE telescope to estimate the rate of sublimation of substances and the surface of the comet’s nucleus.

TESS images of Comet Bernardinelli-Bernstein (C / 2014 UN271), Kuiper Belt objects and asteroids. Credit: Tony L. Farnham et al. / The Planetary Science Journal, 2021
TESS images of Comet Bernardinelli-Bernstein (C / 2014 UN271), Kuiper Belt objects, and asteroids. Credit: Tony L. Farnham et al. / The Planetary Science Journal, 2021

Analysis of TESS images and their comparison with images of inactive Kuiper belt objects and asteroids showed that Bernardinelli-Bernstein showed a faint coma with asymmetry towards the Sun at distances of 23.8 and 21.2 AU from our star, which makes this comet one of the most distant comets, which showed signs of activity before the passage of perihelion. The comet’s activity is associated with the sublimation of frozen carbon monoxide, which is continuous in time and is not the result of spontaneous outbreaks.

Conclusions

Scientists have concluded that the C / 2014 UN271 coma consists of submillimeter-sized grains ejected from the surface of the nucleus at a speed of several tens of meters per second. The upper limit on the rate of formation of CO molecules in a coma is estimated at 2×10 28 molecules per second, the comet’s activity is expected to increase more and more as it approaches the Sun.


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Sources:

EurekAlert! (n.d.). New study shows the largest comet ever observed was active at near-record distance.
Farnham, T. L., Kelley, M. S. P., & Bauer, J. M. (n.d.). Early Activity in Comet C/2014 UN271 Bernardinelli–Bernstein as Observed by TESS. The Planetary Science Journal.
Mathewson, S. (2021, November 30). Giant comet was active way farther from the Sun than expected, scientists confirm. Space.com.
Morales, M. (2021, December 1). NASA’s Tess captures giant active comet moving farther away from the sun. Science Times.
O’Neill, M. (2021, November 30). Astronomers discover largest-known comet was active at near-record distance. SciTechDaily.

Written by Vladislav Tchakarov

Hello, my name is Vladislav and I am glad to have you here on Curiosmos. As a history student, I have a strong passion for history and science, and the opportunity to research and write in this field on a daily basis is a dream come true.

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