The interstellar invader Comet 3I/ATLAS continues to surprise scientists, this time brightening at an unexpectedly fast pace as it approaches the Sun. Experts studying the object do not yet know why this happened.
3I/ATLAS is only the third object known to have entered our solar system from another planetary system — after the cigar-shaped space rock ‘Oumuamuadiscovered passing through the solar system in October 2017, and the first interstellar comet 2I/Borisovobserved in our staryard in August 2019. The brief presence of these bodies in the Solar System offers unique insight into the chemical composition around other stars.
“The reason for the rapid brightening of 3I, which far exceeds the brightening rate of most comets in the Oort cloud at similar r [radial distance]remains unclear,” write the scientists behind the research, Qicheng Zhang of the Lowell Observatory in Flagstaff, Arizona, and Karl Battams, an astrophysicist at the Naval Research Laboratory (NRL) in Washington, DC, in an article discussing the observation published on the Research Repository website arXiv.
The rapid brightening of 3I/ATLAS was observed by STEREO-A and STEREO-B, the twin spacecraft that make up the Solar Earth Relations Observatory (STEREO), the Solar and Heliospheric Sun Observing Observatory (SOHO), and the GOES-19 weather satellite. The observations from space were necessary because ground-based instruments won’t be able to observe the interstellar comet again until it passes from the other side of the sun into its “post-perihelion” phase, escaping the glare of starlight in mid-to-late November 2025.
The team proposes several different mechanisms that could explain the unexpectedly rapid brightening of this extrasolar comet. This could be a result of the speed at which 3I/ATLAS is approaching the sun; alternatively, it could tell scientists something about the comet itself. This is exciting because if the internal composition of 3I/ATLAS is different from that of the Oort cloud comet nucleus, this could mean that the planetary system from which it originated also has a different chemical composition.
“Peculiarities in core properties such as composition, shape or structure – which may have been acquired from the host system or during long interstellar travel – may also contribute [to the rapid brightening]Zhan and Battams continued. “Without an established physical explanation, the prospects for 3I’s post-perihelion behavior remain uncertain, and a brightness plateau—or even a brief continuation of its pre-perihelion brightening—seems as likely as a rapid fading after perihelion.”
The authors also suggest that sublimation may be occurring differently than expected for 3I/ATLAS because the interstellar comet was still dominated by carbon dioxide sublimation at an unusually short distance from the sun, about three times the distance between Earth and our star. This could have resulted in cooling that has so far suppressed the sublimation of water ice into steam.
Apparently, 3I/ATLAS continues to baffle and intrigue scientists in equal measure, and it’s pretty certain that once it escapes the glare of the sun, we’ll discover even more interesting facts surrounding this interstellar interloper.
“Continued observations can help provide a more definitive explanation of comet behavior,” the duo of scientists concluded.
The paper on these results can be viewed in the preprint repository arxiv.
Source link
Comets,Astronomy,Solar System , , #Interstellar #invader #comet #3IATLAS #full #surprises #unexpected #brightening #baffles #scientists, #Interstellar #invader #comet #3IATLAS #full #surprises #unexpected #brightening #baffles #scientists, 1761970203, interstellar-invader-comet-3i-atlas-still-full-of-surprises-unexpected-brightening-baffles-scientists