# 2I/Borisov: A C2 depleted interstellar comet

C. Opitom, A. Fitzsimmons, E. Jehin, Y. Moulane, O. Hainaut, K. J. Meech, B. Yang, Colin Snodgrass, Marco Micheli, J. V. Keane, Z. Benkhaldoun, J. T. Kleyna

Research output: Contribution to journalArticle

### Abstract

The discovery of the first active interstellar object 2I/Borisov provides an unprecedented opportunity to study planetary formation processes in another planetary system. In particular, spectroscopic observations of 2I allow us to constrain the composition of its nuclear ices. We obtained optical spectra of 2I with the 4.2 m William Herschel and 2.5 m Isaac Newton telescopes between 2019 September 30 and October 13, when the comet was between 2.5 au to 2.4 au from the Sun. We also imaged the comet with broadband filters on 15 nights from September 11 to October 17 with the TRAPPIST-North telescope. Broad-band imaging show that the dust coma colours (B-V=0.82$\pm$0.02, V-R=0.46$\pm$0.03, R-I=0.44$\pm$0.03, B-R=1.28$\pm$0.03) are the same as for Solar System comets. We detect CN emission in all spectra with production rates between $1.8\times10^{24}$ and $2.1\times10^{24}$molec/s. No other species are detected. We determine 3-sigma upper limits for C$_2$, C$_3$, and OH production rates of $6\times10^{23}$molec/s, $3\times10^{23}$molec/s and $2\times10^{27}$molec/s, respectively, on October 02. There is no significant increase of the CN production rate or A(0)f$\rho$ during our observing period. Finally, we place a 3-sigma upper limit on the Q(C$_2$)/Q(CN) ratio of 0.3 (on October 13). From this, we conclude that 2I is highly depleted in C$_2$, and may have a composition similar to Solar System carbon-chain depleted comets
Language English Astronomy and Astrophysics Accepted - 23 Oct 2019

### Fingerprint

comets
comet
solar system
CN emission
telescopes
planetary systems
coma
night
newton
optical spectrum
ice
dust
filter
color
filters
carbon
rate

• astro-ph.EP

### Cite this

Opitom, C., Fitzsimmons, A., Jehin, E., Moulane, Y., Hainaut, O., Meech, K. J., ... Kleyna, J. T. (Accepted/In press). 2I/Borisov: A C2 depleted interstellar comet. Astronomy and Astrophysics.
Opitom, C. ; Fitzsimmons, A. ; Jehin, E. ; Moulane, Y. ; Hainaut, O. ; Meech, K. J. ; Yang, B. ; Snodgrass, Colin ; Micheli, Marco ; Keane, J. V. ; Benkhaldoun, Z. ; Kleyna, J. T. / 2I/Borisov: A C2 depleted interstellar comet. In: Astronomy and Astrophysics. 2019.
@article{cb6c1ac8c94e4ec29206673159a53d31,
title = "2I/Borisov: A C2 depleted interstellar comet",
abstract = "The discovery of the first active interstellar object 2I/Borisov provides an unprecedented opportunity to study planetary formation processes in another planetary system. In particular, spectroscopic observations of 2I allow us to constrain the composition of its nuclear ices. We obtained optical spectra of 2I with the 4.2 m William Herschel and 2.5 m Isaac Newton telescopes between 2019 September 30 and October 13, when the comet was between 2.5 au to 2.4 au from the Sun. We also imaged the comet with broadband filters on 15 nights from September 11 to October 17 with the TRAPPIST-North telescope. Broad-band imaging show that the dust coma colours (B-V=0.82$\pm$0.02, V-R=0.46$\pm$0.03, R-I=0.44$\pm$0.03, B-R=1.28$\pm$0.03) are the same as for Solar System comets. We detect CN emission in all spectra with production rates between $1.8\times10^{24}$ and $2.1\times10^{24}$molec/s. No other species are detected. We determine 3-sigma upper limits for C$_2$, C$_3$, and OH production rates of $6\times10^{23}$molec/s, $3\times10^{23}$molec/s and $2\times10^{27}$molec/s, respectively, on October 02. There is no significant increase of the CN production rate or A(0)f$\rho$ during our observing period. Finally, we place a 3-sigma upper limit on the Q(C$_2$)/Q(CN) ratio of 0.3 (on October 13). From this, we conclude that 2I is highly depleted in C$_2$, and may have a composition similar to Solar System carbon-chain depleted comets",
keywords = "astro-ph.EP",
author = "C. Opitom and A. Fitzsimmons and E. Jehin and Y. Moulane and O. Hainaut and Meech, {K. J.} and B. Yang and Colin Snodgrass and Marco Micheli and Keane, {J. V.} and Z. Benkhaldoun and Kleyna, {J. T.}",
year = "2019",
month = "10",
day = "23",
language = "English",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",

}

Opitom, C, Fitzsimmons, A, Jehin, E, Moulane, Y, Hainaut, O, Meech, KJ, Yang, B, Snodgrass, C, Micheli, M, Keane, JV, Benkhaldoun, Z & Kleyna, JT 2019, '2I/Borisov: A C2 depleted interstellar comet', Astronomy and Astrophysics.

2I/Borisov: A C2 depleted interstellar comet. / Opitom, C.; Fitzsimmons, A.; Jehin, E.; Moulane, Y.; Hainaut, O.; Meech, K. J.; Yang, B.; Snodgrass, Colin; Micheli, Marco; Keane, J. V.; Benkhaldoun, Z.; Kleyna, J. T.

In: Astronomy and Astrophysics, 23.10.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 2I/Borisov: A C2 depleted interstellar comet

AU - Opitom, C.

AU - Fitzsimmons, A.

AU - Jehin, E.

AU - Moulane, Y.

AU - Hainaut, O.

AU - Meech, K. J.

AU - Yang, B.

AU - Snodgrass, Colin

AU - Micheli, Marco

AU - Keane, J. V.

AU - Benkhaldoun, Z.

AU - Kleyna, J. T.

PY - 2019/10/23

Y1 - 2019/10/23

N2 - The discovery of the first active interstellar object 2I/Borisov provides an unprecedented opportunity to study planetary formation processes in another planetary system. In particular, spectroscopic observations of 2I allow us to constrain the composition of its nuclear ices. We obtained optical spectra of 2I with the 4.2 m William Herschel and 2.5 m Isaac Newton telescopes between 2019 September 30 and October 13, when the comet was between 2.5 au to 2.4 au from the Sun. We also imaged the comet with broadband filters on 15 nights from September 11 to October 17 with the TRAPPIST-North telescope. Broad-band imaging show that the dust coma colours (B-V=0.82$\pm$0.02, V-R=0.46$\pm$0.03, R-I=0.44$\pm$0.03, B-R=1.28$\pm$0.03) are the same as for Solar System comets. We detect CN emission in all spectra with production rates between $1.8\times10^{24}$ and $2.1\times10^{24}$molec/s. No other species are detected. We determine 3-sigma upper limits for C$_2$, C$_3$, and OH production rates of $6\times10^{23}$molec/s, $3\times10^{23}$molec/s and $2\times10^{27}$molec/s, respectively, on October 02. There is no significant increase of the CN production rate or A(0)f$\rho$ during our observing period. Finally, we place a 3-sigma upper limit on the Q(C$_2$)/Q(CN) ratio of 0.3 (on October 13). From this, we conclude that 2I is highly depleted in C$_2$, and may have a composition similar to Solar System carbon-chain depleted comets

AB - The discovery of the first active interstellar object 2I/Borisov provides an unprecedented opportunity to study planetary formation processes in another planetary system. In particular, spectroscopic observations of 2I allow us to constrain the composition of its nuclear ices. We obtained optical spectra of 2I with the 4.2 m William Herschel and 2.5 m Isaac Newton telescopes between 2019 September 30 and October 13, when the comet was between 2.5 au to 2.4 au from the Sun. We also imaged the comet with broadband filters on 15 nights from September 11 to October 17 with the TRAPPIST-North telescope. Broad-band imaging show that the dust coma colours (B-V=0.82$\pm$0.02, V-R=0.46$\pm$0.03, R-I=0.44$\pm$0.03, B-R=1.28$\pm$0.03) are the same as for Solar System comets. We detect CN emission in all spectra with production rates between $1.8\times10^{24}$ and $2.1\times10^{24}$molec/s. No other species are detected. We determine 3-sigma upper limits for C$_2$, C$_3$, and OH production rates of $6\times10^{23}$molec/s, $3\times10^{23}$molec/s and $2\times10^{27}$molec/s, respectively, on October 02. There is no significant increase of the CN production rate or A(0)f$\rho$ during our observing period. Finally, we place a 3-sigma upper limit on the Q(C$_2$)/Q(CN) ratio of 0.3 (on October 13). From this, we conclude that 2I is highly depleted in C$_2$, and may have a composition similar to Solar System carbon-chain depleted comets

KW - astro-ph.EP

M3 - Article

JO - Astronomy and Astrophysics

T2 - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

ER -

Opitom C, Fitzsimmons A, Jehin E, Moulane Y, Hainaut O, Meech KJ et al. 2I/Borisov: A C2 depleted interstellar comet. Astronomy and Astrophysics. 2019 Oct 23.