2019/10/31 by Theodore Kareta, Jennifer Andrews, John W. Noonan +11 · 39 citations
Physics and Astronomy · #Asteroid #Astro and Planetary Science #Astrophysics and Star Formation Studies #Comet #Extraterrestrial life #Formation and evolution of the Solar System #Planetary system #Planetesimal #Production rate #Solar System #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.3847/2041-8213/ab6a08
published in The Astrophysical Journal Letters 889(2), L38 (IOP Publishing) · 10 pages, 3 figures, in revision at Astrophysical Journal Letters with new data
arxiv created 2019/11/25 · openalex publication_date 2020/02/01 · arxiv updated 2020/02/12 · openalex created_date 2020/02/14 · openalex updated_date 2026/08/05
Abstract The composition of comets in the solar system comes in multiple groups thought to encode information about their formation in different regions of the outer protosolar disk. The recent discovery of the second interstellar object, 2I/Borisov, allows for spectroscopic investigations into its gas content and a preliminary classification of it within the solar system comet taxonomies to test the applicability of planetesimal formation models to other stellar systems. We present spectroscopic and imaging observations from 2019 September 20 through October 26 from the Bok, MMT telescope (formerly the Multiple Mirror Telescope, Mount Hopkins, Arizona), and Large Binocular Telescopes. We identify CN in the comet’s spectrum and set precise upper limits on the abundance of C 2 on all dates in October. We use a Haser model to convert our integrated fluxes to production rates and find Q (CN) = (1.1–1.9) ∗ 10 24 mols s −1 increasing over 2019 October 1 to 26, consistent with contemporaneous observations. We set our lowest upper limit on a C 2 production rate, Q (C 2 ) < 1.6 ∗ 10 23 mols s −1 on 2019 October 10. The measured upper limit ratio for that date Q (C 2 )/ Q (CN) < 0.1 indicates that 2I/Borisov is strongly in the (carbon-chain) “depleted” taxonomic group if there is any C 2 production at all. Most “depleted” comets are Jupiter-family comets (JFCs), perhaps indicating a similarity in formation conditions between the most depleted of the JFCs and 2I/Borisov. More work is needed to understand the applicability of our knowledge of solar system comet taxonomies onto interstellar objects and we discuss future work that could help to clarify the usefulness of the approach.