Detection of CN gas in Interstellar Object 2I/Borisov

Abstract

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) = $(3.7\pm 0.4)\times 10^{24}$ s${}^{-1}$, using a simple Haser model with an outflow velocity of 0.5 km s${}^{-1}$. No other emission was detected, with an upper limit to the production rate of C${}_2$ of $4\times 10^{24}$ s${}^{-1}$. The spectral reflectance slope of the dust coma over $3900$ Å $<\lambda <6000$ Å\ is steeper than at longer wavelengths, as found for other comets. Broad band $R_c$ photometry on 2019 September 19 gave a dust production rate of $Af\rho =143\pm 10$ cm. Modelling 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.

arXiv comment9 pages, 4 figures, accepted for publication in ApJL

References in corpus (11)

• An Observational Upper Limit on the Interstellar Number Density of Asteroids and Comets
• The Natural History of 'Oumuamua
• Thirty Years of Cometary Spectroscopy from McDonald Observatory
• Spitzer Observations of Interstellar Object 1I/`Oumuamua
• 1I/2017 U1 (`Oumuamua) is Hot: Imaging, Spectroscopy and Search of Meteor Activity
• The tumbling rotational state of 1I/`Oumuamua
• The Excited Spin State of 1I/2017 U1 `Oumuamua
• Cometary compositions compared with protoplanetary disk midplane chemical evolution. An emerging chemical evolution taxonomy for comets
• TRAPPIST photometry and imaging monitoring of comet C/2013 R1(Lovejoy): Implications for the origin of daughter species
• Long-term activity and outburst of comet C/2013 A1 (Siding Spring) from narrow-band photometry and long-slit spectroscopy
• Near-UV and optical spectroscopy of comets using the ISIS spectrograph on the WHT

Cited by in corpus (43)

• Initial Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)
• The carbon monoxide-rich interstellar comet 2I/Borisov
• The Nucleus of Interstellar Comet 2I/Borisov
• Solar System Physics for Exoplanet Research
• GJ 273: On the formation, dynamical evolution and habitability of a planetary system hosted by an M dwarf at 3.75 parsec
• Detection of a Water Tracer in Interstellar Comet 2I/Borisov
• Pre-discovery Activity of New Interstellar Comet 2I/Borisov Beyond 5 AU
• Water production rates and activity of interstellar comet 2I/Borisov
• 1I/'Oumuamua as an N2 ice fragment of an exo-pluto surface. II. Generation of N2 ice fragments and the origin of 'Oumuamua
• Interstellar comet 3I/ATLAS: discovery and physical description
• Detection of Diatomic Carbon in 2I/Borisov
• Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations
• Exocomets from a Solar System Perspective
• Carbon Chain Depletion of 2I/Borisov
• 1I/'Oumuamua as an N2 ice fragment of an exo-Pluto surface: I. size and compositional constraints
• Outburst and Splitting of Interstellar Comet 2I/Borisov
• Coma Anisotropy and the Rotation Pole of Interstellar Comet 2I/Borisov
• Constraints on the Occurrence of 'Oumuamua-Like Objects
• Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes
• Gaseous atomic nickel in the coma of interstellar comet 2I/Borisov
• Compact pebbles and the evolution of volatiles in the interstellar comet 2I/Borisov
• A search for the origin of the interstellar comet 2I/Borisov
• The similarity of the interstellar comet 2I/Borisov to solar system comets from high resolution optical spectroscopy
• Capture of interstellar objects: a source of long-period comets
• Activity of the first interstellar comet 2I/Borisov around perihelion: Results from Indian observatories
• SISPO: Space Imaging Simulator for Proximity Operations
• Constraints on the Spin-Pole Orientation, Jet Morphology and Rotation of Interstellar Comet 2I/Borisov with Deep HST Imaging
• X-SHOOTER Spectrum of Comet 3I/ATLAS: Insights into a Distant Interstellar Visitor
• Very Large Telescope Observations of Interstellar Comet 3I/ATLAS. II. From Quiescence to Glow: Dramatic Rise of Ni i Emission and Incipient CN Outgassing at Large Heliocentric Distances*
• Searching for water ice in the coma of interstellar object 2I/Borisov
• Ice-Coated Pebble Drift as a Possible Explanation for Peculiar Cometary CO/H2O Ratios
• FeI and NiI in cometary atmospheres. Connections between the NiI/FeI abundance ratio and chemical characteristics of Jupiter-family and Oort-cloud comets
• Emission from HCN and CH${}_3$OH in comets. Onsala 20-m observations and radiative transfer modelling
• Tails: Chasing Comets with the Zwicky Transient Facility and Deep Learning
• Capture of interstellar objects II: by the Solar system
• Pre-perihelion Monitoring of Interstellar Comet 2I/Borisov
• Oumuamuas passing through molecular clouds
• Near-Discovery SOAR Photometry of the Third Interstellar Object: 3I/ATLAS
• FLAMINGOS-2 infrared photometry of 2I/Borisov
• Constraining the orientation of the spin axes of extrasolar minor bodies 1I/2017 U1 (`Oumuamua) and 2I/Borisov
• Pre-perihelion Volatile Evolution of Interstellar Comet 3I/ATLAS Indicating Significant Contribution from Extended Source in the Coma
• Ejected from home: C/1980 E1 (Bowell) and C/2024 L5 (ATLAS)
• Dynamical simulation of the Interstellar Comet 3I/ATLAS