Optical observations of comet 67P/Churyumov-Gerasimenko

Abstract

From longslit spectra obtained during the 1996 perihelion passage of Comet 67P(Churyumov-Gerasimenko, a CN production rate of (1.35 ± 0.35) x 10_25 molecules s_-1 was determined and an upper limit for the C3 production rate of 1 x 10_25 molecules s_-1 was derived. The dust color and dust activity were determined from the continuum light in the spectra. A neutral dust color was determined between 4070 Å und 4600 Å. The CN production rate and the Afp parameter, determined to (428.2 ± 59,8) cm were similar to the values of the 1982 perihelion passage, indicating that the comet's acitivity did noch change significantly in recent orbital passages. A first crude estimate of the dust production rate indicates a high dust to gas mass ratio. R-filter images taken in March 2003 were used to study the dust coma morphology. Two jet structures were seen in the coma; these structures show no variation within the observing period from March 7 to May 30, 2003. The orientation of these stationary structures suggests an inclination of the rotation axis of the nucleus of approximately 40° with respect to the orbital plane.