Comets; Cometary atmospheres; Planetary system formation
Abstract :
[en] The detection of interstellar objects passing through the solar system offers the promise of constraining the physical and chemical processes involved in planetary formation in other extrasolar systems. While the effect of outgassing by 1I/2017 U1 (’Oumuamua) was dynamically observed, no direct detection of the ejected material was made. The discovery of the active interstellar comet 2I/Borisov means spectroscopic investigations of the sublimated ices is possible for this object. We report the first detection of gas emitted by an interstellar comet via the near-UV emission of CN from 2I/Borisov at a heliocentric distance of r = 2.7 au on 2019 September 20. The production rate was found to be Q(CN) = (3.7 ± 0.4) × 10[SUP]24[/SUP] s[SUP]−1[/SUP], using a simple Haser model with an outflow velocity of 0.5 km s[SUP]−1[/SUP]. No other emission was detected, with an upper limit to the production rate of C[SUB]2[/SUB] of 4 × 10[SUP]24[/SUP] s[SUP]−1[/SUP]. The spectral reflectance slope of the dust coma over 3900 Å < λ < 6000 Å is steeper than at longer wavelengths, as found for other comets. Broadband R [SUB] c [/SUB] photometry on 2019 September 19 gave a dust production rate of Afρ = 143 ± 10 cm. Modeling of the observed gas and dust production rates constrains the nuclear radius to 0.7─3.3 km assuming reasonable nuclear properties. Overall, we find the gas, dust, and nuclear properties for the first active interstellar object are similar to normal solar system comets.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Fitzsimmons, Alan; Astrophysics Research Centre, Queen’s University Belfast, Belfast BT7 1NN, UK
Hainaut, Olivier; European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei München, Germany
Meech, Karen J.; Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 USA
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Moulane, Youssef ; European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile ; STAR Institute, Université de Liege, Allée du 6 août, 19C, B-4000 Liege, Belgium ; Oukaimeden Observatory, Cadi Ayyad University, Morocco
Opitom, Cyrielle; European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
Yang, Bin; European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile
Keane, Jacqueline V.; Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 USA
Kleyna, Jan T.; Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 USA
Micheli, Marco; ESA NEO Coordination Centre, Largo Galileo Galilei, 1, I-00044 Frascati (RM), Italy ; INAF—Osservatorio Astronomico di Roma, Via Frascati, 33, I-00040 Monte Porzio Catone (RM), Italy
Snodgrass, Colin; Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, UK)
Language :
English
Title :
Detection of CN Gas in Interstellar Object 2I/Borisov
Publication date :
01 November 2019
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
University of Chicago Press, United States - Illinois
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