2I/Borisov is the first-ever observed interstellar comet ( and the second detected interstellar object ) .
It was discovered on 30 August 2019 and has a heliocentric orbital eccentricity of \sim 3.35 , corresponding to a hyperbolic orbit that is unbound to the Sun .
Given that it is an interstellar object , it is of interest to compare its properties – such as composition and activity – with the comets in our Solar System .
This study reports low-resolution optical spectra of 2I/Borisov .
The spectra were obtained by the MDM observatory Hiltner 2.4m telescope/Ohio State Multi-Object Spectrograph ( on 1 and 5 November 2019 ) .
The wavelength coverage spanned from 3700 \AA to 9200 \AA .
The dust continuum reflectance spectra of 2I/Borisov show that the spectral slope is steeper in the blue end of the spectrum ( compared to the red ) .
The spectra of 2I/Borisov clearly show CN emission at 3880 \AA , as well as C _ { 2 } emission at both 4750 \AA and 5150 \AA .
Using a Haser model to covert the observed fluxes into estimates for the molecular production rates , we find Q ( CN ) = 2.4 \pm 0.2 \times 10 ^ { 24 } s ^ { -1 } , and Q ( C _ { 2 } ) = 5.5 \pm 0.4 \times 10 ^ { 23 } s ^ { -1 } .
Our Q ( CN ) estimate is consistent with contemporaneous observations , and the Q ( C _ { 2 } ) estimate is generally below the upper limits of previous studies .
We derived the ratio Q ( C _ { 2 } ) / Q ( CN ) = 0.2 \pm 0.1 , which indicates that 2I/Borisov is depleted in carbon chain species , but is not empty .
This feature is not rare for the comets in our Solar System , especially in the class of Jupiter Family Comets .