ALMA Observes Molecular Activity in Largest Oort Cloud Comet C/2014 UN271

Astronomers utilizing the Atacama Large Millimeter/submillimeter Array (ALMA) have made significant observations of comet C/2014 UN271, also known as Bernardinelli-Bernstein, while it was located at a remarkable distance of 16.6 astronomical units (AU) from the Sun, which is more than halfway to Neptune. This comet, recognized as the largest and the second most distantly active comet documented from the Oort Cloud, measures approximately 140 kilometers (85 miles) in diameter, exceeding the size of most known comets by over tenfold.

Discovered in 2014 by astronomers Pedro Bernardinelli and Gary Bernstein during the Dark Energy Survey, C/2014 UN271 possesses a lengthy orbital period that spans millions of years. Until the recent findings, the behavior of such cold and distant celestial bodies remained largely a mystery. The latest observations from ALMA have revealed complex jets of carbon monoxide gas erupting from the nucleus of the comet, providing unprecedented evidence regarding the dynamics driving its activity at such a significant distance from the Sun.

"These measurements give us a look at how this enormous, icy world works," stated Dr. Nathan Roth, an astronomer affiliated with American University and NASA’s Goddard Space Flight Center. He noted that the observations are revealing explosive outgassing patterns, raising new inquiries about the comet's evolution as it continues its journey towards the inner Solar System.

ALMA's observations involved capturing light emitted from carbon monoxide gas present in the comet's atmosphere, as well as thermal emissions. This high-sensitivity and high-resolution capability allowed scientists to detect the faint signals from this frigid and remote object. Furthermore, these findings align with previous ALMA data that characterized the large nucleus of the comet, confirming its status as the largest known Oort Cloud comet.

According to the research team, the discovery marks the first identification of molecular outgassing in this record-setting comet and offers a rare insight into the chemistry and dynamics of objects originating from the outermost regions of our Solar System. As C/2014 UN271 approaches the Sun, astronomers anticipate that additional frozen gases will vaporize, potentially revealing further information regarding the comet’s primordial composition and that of the early Solar System.

Such discoveries may also contribute to answering fundamental questions regarding the origins of Earth and its water, as well as the conditions that may foster life-friendly environments elsewhere in the universe. The research team's findings have been published in the Astrophysical Journal Letters, detailing their comprehensive analysis of this remarkable celestial entity.

In summary, the ALMA observations of comet C/2014 UN271 not only highlight the advanced capabilities of contemporary astronomical instruments but also underscore the importance of continued research into the dynamics of distant celestial bodies. As these insights unfold, they may illuminate the mysteries of our Solar System and beyond, fostering a deeper understanding of the cosmos.

For further information, please refer to the study by Nathan X. Roth et al. titled "The First Detection of Molecular Activity in the Largest Known Oort Cloud Comet: ALMA Imaging of C/2014 UN271 (Bernardinelli-Bernstein) at 16.6 AU from the Sun," published in the Astrophysical Journal Letters, Volume 986, L22, doi:10.3847/2041-8213/add526.