Carbon monoxide gas produced by a giant impact in the inner region of a young system

Article

关键词: DEBRIS DISCS;    ORIGIN;    SCATTERING;    EXOCOMETS;    DISKS;    CO;    EVOLUTION;    COLLISION;    COMETS;    STARS;   

DOI  :  10.1038/s41586-021-03872-x

来源: SCIE

【 摘 要 】

Models of terrestrial planet formation predict that the final stages of planetary assembly-lasting tens of millions of years beyond the dispersal of young protoplanetary disks-are dominated by planetary collisions. It is through these giant impacts that planets like the young Earth grow to their final mass and achieve long-term stable orbital configurations(1). A key prediction is that these impacts produce debris. So far, the most compelling observational evidence for post-impact debris comes from the planetary system around the nearby 23-million-year-old A-type star HD 172555. This system shows large amounts of fine dust with an unusually steep size distribution and atypical dust composition, previously attributed to either a hypervelocity impact(2,3) or a massive asteroid belt(4). Here we report the spectrally resolved detection of a carbon monoxide gas ring co-orbiting with dusty debris around HD 172555 between about six and nine astronomical units-a region analogous to the outer terrestrial planet region of our Solar System. Taken together, the dust and carbon monoxide detections favour a giant impact between large, volatile-rich bodies. This suggests that planetary-scale collisions, analogous to the Moon-forming impact, can release large amounts of gas as well as debris, and that this gas is observable, providing a window into the composition of young planets. A carbon monoxide gas ring co-orbiting with dusty debris is observed in the outer terrestrial planet region of the star HD 172555, which indicates that a planetary-scale impact took place.

【 授权许可】

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