Near-ultraviolet and visible spectrophotometry of comet Halley from Vega 2

Guy Moreels (1) , M. Gogoshev (2) , V. A. Krasnopolsky (3) , J. Clairemidi (1) , M. Vincent (1) , J.-P. Parisot (1) , Jean-Loup Bertaux (4) , Jacques-Emile Blamont (4) , M.-C. Festou (1) , Ts. Gogosheva (2) , S. Sargoichev (2) , K. Palasov (2) , V. I. Moroz (3) , A. A. Krysko (3) , V. Vanyšek (5)

1 Observatoire de Besançon
2 Observatory Stara Zagora
3 IKI - Space Research Institute of the Russian Academy of Sciences
4 SA - Service d'aéronomie
5 Ondřejov Observatory of the Prague Astronomical Institute

We report results obtained by the near-ultraviolet and visible channel (V) of the TKS instrument1 carried by Vega 2 during the hour preceding its closest approach to comet Halley. The brightness of the OH (0, 0) band is found to be 1.2, 1.4 and 1.8 MR (megarayleigh; 1 R = 106 photons cm−2 s−1 (4π sr)−1) at distances of 4,900, 2,450 and <1,000 km from the nucleus. The OH gas production rate is estimated to have been ∼9×1029 molecules s−1 on 9 March 1986. Modifications in the structure of the OH and CN bands observed as the distance from the line of sight to the nucleus decreases probably reflect the change in the vibration–rotation line intensity distribution of the radicals, due to the presence of radicals created in an excited state by the photolysis of their parent molecules.

Domains: Sciences of the Universe [physics]

Guy Moreels, M. Gogoshev, V. A. Krasnopolsky, J. Clairemidi, M. Vincent, et al.. Near-ultraviolet and visible spectrophotometry of comet Halley from Vega 2. Nature, 1986, 321 (S6067), pp.271-273. ⟨10.1038/321271a0⟩. ⟨insu-03584142⟩