We report the clear detection of C _ { 2 } and of abundant NH _ { 2 } in the first prominently active interstellar comet , 2I/Borisov .
We observed 2I on three nights in November 2019 at optical wavelengths 4800–9300 Åwith the Multi-Unit Spectroscopic Explorer ( MUSE ) integral-field spectrograph on the ESO/Very Large Telescope .
These data , together with observations close in time from both 0.6-m TRAPPIST telescopes , provide constraints on the production rates of species of gas in 2I ’ s coma .
From the MUSE detection on all epochs of several bands of the optical emission of the C _ { 2 } Swan system , a rich emission spectrum of NH _ { 2 } with many highly visible bands , and the red ( 1-0 ) bandhead of CN , together with violet CN detections by TRAPPIST , we infer production rates of Q ( C _ { 2 } ) = 1.1 \times 10 ^ { 24 } mol s ^ { -1 } , Q ( NH _ { 2 } ) = 4.8 \times 10 ^ { 24 } mol s ^ { -1 } and Q ( CN ) = ( 1.8 \pm 0.2 ) \times 10 ^ { 24 } mol s ^ { -1 } .
In late November at 2.03 au , 2I had a production ratio of C _ { 2 } /CN = 0.61 , only barely carbon-chain depleted , in contrast to earlier reports measured further from the Sun of strong carbon-chain depletion .
Thus , 2I has shown evolution in its C _ { 2 } production rate : a parent molecule reservoir has started sublimating .
At Q ( NH _ { 2 } ) / Q ( CN ) = 2.7 , this second interstellar object is enriched in NH _ { 2 } , relative to the known Solar System sample .