Astronomers have discovered that the largest comet from the Oort Cloud, a shell of icy bodies at the very edge of the solar system, is bursting with chemical activity.
Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the team discovered that C/2014 UN271, an 85-mile-wide (137 km) body around 10 times the size of the average comet and also known as Bernardinelli-Bernstein, is erupting with complex and evolving jets of carbon monoxide gas.
Now located halfway between the sun and the solar system’s furthest planet, Neptune (or 16.6 times the distance between the Earth and our star), C/2014 UN271 becomes the second-most distant comet originating from the Oort Cloud that has been seen to be chemically active. The observations are also the first direct evidence of what drives cometary activity when these icy bodies are far from the sun.
“These measurements give us a look at how this enormous, icy world works,” team leader and NASA Goddard Space Flight Center researcher Nathan Roth said in a statement. “We’re seeing explosive outgblocking patterns that raise new questions about how this comet will evolve as it continues its journey toward the inner solar system.”
ALMA was able to observe C/2014 UN271 despite its distance from the sun via the carbon monoxide in its atmosphere and its thermal emissions.
Previously, the sensitivity of this ground-breaking instrument, composed of an array of 66 radio antennas located in the Atacama Desert region of northern Chile, allowed scientists to determine the size of the core or “nucleus” of the comet.
Building upon this, the team was able to precisely determine the comet’s entire size and the amount of dust that envelopes its core or “nucleus.” This confirmed the status of C/2014 UN271 as the largest Oort Cloud comet ever found.
Adding to the clearer picture painted of this giant comet by ALMA was the first detection of molecular outgblocking for C/2014 UN271. This has afforded scientists a rare look at the chemistry of icy bodies from the very edge of the solar system.
C/2014 UN271 is approaching the sun, and as it does, the comet will begin to heat up, and more frozen material within it will turn gaseous and erupt from its icy shell.
Because comets are thought to be composed of unspoiled material left over from the formation of the solar system around 4.6 billion years ago, this could offer a glimpse at the conditions in which Earth and the other planets were formed.
The team’s research was published on June 12 in The Astrophysical Journal Letters.
