Activity of the first interstellar comet 2I/Borisov around perihelion: Results from Indian observatories

Abstract

Comet 2I/Borisov is the first true interstellar comet discovered. Here we present results from observational programs at two Indian observatories, 2 m Himalayan Chandra Telescope at the Indian Astronomical Observatory, Hanle (HCT) and 1.2 m telescope at the Mount Abu Infrared Observatory (MIRO). Two epochs of imaging and spectroscopy were carried out at the HCT and three epochs of imaging at MIRO. We found CN to be the dominant molecular emission on both epochs, 31/11/2019 and 22/12/2019, at distances of r${}_H$ = 2.013 and 2.031 AU respectively. The comet was inferred to be relatively depleted in Carbon bearing molecules on the basis of low $C_2$ and $C_3$ abundances. We find the production rate ratio, Q($C_2$)/Q(CN) = 0.54 $\pm$ 0.18, pre-perihelion and Q($C_2$)/Q(CN) = 0.34 $\pm$ 0.12 post-perihelion. This classifies the comet as being moderately depleted in carbon chain molecules. Using the results from spectroscopic observations, we believe the comet to have a chemically heterogeneous surface having variation in abundance of carbon chain molecules. From imaging observations we infer a dust-to-gas ratio similar to carbon chain depleted comets of the Solar system. We also compute the nucleus size to be in the range $0.18\le r\le 3.1$ Km. Our observations show that 2I/Borisov's behaviour is analogous to that of the Solar system comets.

Accepted for publication in MNRAS, 10 pages, 8 figures

References in corpus (16)

• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes
• Initial characterization of interstellar comet 2I/Borisov
• Initial Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)
• The carbon monoxide-rich interstellar comet 2I/Borisov
• Unusually High CO Abundance of the First Active Interstellar Comet
• 2I/Borisov: A C${}_2$ depleted interstellar comet
• Detection of CN gas in Interstellar Object 2I/Borisov
• The Nucleus of Interstellar Comet 2I/Borisov
• Detection of Diatomic Carbon in 2I/Borisov
• Carbon Chain Depletion of 2I/Borisov
• Outburst and Splitting of Interstellar Comet 2I/Borisov
• Coma Anisotropy and the Rotation Pole of Interstellar Comet 2I/Borisov
• Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes
• The visible and near-infrared spectra of asteroids in cometary orbits
• Interstellar comet 2I/Borisov as seen by MUSE: C${}_2$, NH${}_2$ and red CN detections

Cited by in corpus (3)

• The similarity of the interstellar comet 2I/Borisov to solar system comets from high resolution optical spectroscopy
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• A comprehensive model of morphologically realistic Cosmic Dust particles: an application to mimic the unusual Polarization properties of the interstellar Comet 2I/Borisov