Exocomets from a Solar System Perspective

Paul Strøm , Dennis Bodewits , Matthew Knight , Flavien Kiefer (1) , Geraint Jones , Quentin Kral (2) , Luca Matrà , Eva Bodman , Maria Teresa Capria , Ilsedore Cleeves , Alan Fitzsimmons , Nader Haghighipour , John Harrison , Daniela Iglesias , Mihkel Kama , Harold Linnartz , Liton Majumdar , Ernst de Mooij , Stefanie Milam , Cyrielle Opitom , Isabel Rebollido , Laura Rogers , Colin Snodgrass , Clara Sousa-Silva , Siyi Xu , Zhong-Yi Lin , Sebastian Zieba

1 IAP - Institut d'Astrophysique de Paris
2 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics

Exocomets are small bodies releasing gas and dust which orbit stars other than the Sun. Their existence was first inferred from the detection of variable absorption features in stellar spectra in the late 1980s using spectroscopy. More recently, they have been detected through photometric transits from space, and through far-IR/mm gas emission within debris disks. As (exo)comets are considered to contain the most pristine material accessible in stellar systems, they hold the potential to give us information about early stage formation and evolution conditions of extra solar systems. In the solar system, comets carry the physical and chemical memory of the protoplanetary disk environment where they formed, providing relevant information on processes in the primordial solar nebula. The aim of this paper is to compare essential compositional properties between solar system comets and exocomets to allow for the development of new observational methods and techniques. The paper aims to highlight commonalities and to discuss differences which may aid the communication between the involved research communities and perhaps also avoid misconceptions. The compositional properties of solar system comets and exocomets are summarized before providing an observational comparison between them. Exocomets likely vary in their composition depending on their formation environment like solar system comets do, and since exocomets are not resolved spatially, they pose a challenge when comparing them to high fidelity observations of solar system comets. Observations of gas around main sequence stars, spectroscopic observations of "polluted" white dwarf atmospheres and spectroscopic observations of transiting exocomets suggest that exocomets may show compositional similarities with solar system comets. The recent interstellar visitor 2I/Borisov showed gas, dust and nuclear properties similar to that of solar system comets. This raises the tantalising prospect that observations of interstellar comets may help bridge the fields of exocomet and solar system comets.

Mots clés: Comets; Exocomets; Extrasolar Small Bodies

Domaines: Astrophysique [astro-ph]

Paul Strøm, Dennis Bodewits, Matthew Knight, Flavien Kiefer, Geraint Jones, et al.. Exocomets from a Solar System Perspective. Publications of the Astronomical Society of the Pacific, 2020, 132 (1016), pp.101001. ⟨10.1088/1538-3873/aba6a0⟩. ⟨hal-03254770⟩