The dust environment of comet 67P/Churyumov-Gerasimenko^*

¹ INAF - Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34131 Trieste, Italy
² Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
³ INAF - Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
⁴ Institute of Planetary Research, DLR Rutherfordstrasse 2, 12849 Berlin, Germany
⁵ Unione Astrofili Italiani, UAI
⁶ Osservatorio di Talmassons, CAST, Talmassons (Ud), Italy

Corresponding author: M. Fulle, fulle@ts.astro.it

Received: 4 December 2003
Accepted: 6 April 2004

Abstract

The new target of the ESA Rosetta Mission is comet 67P/Churyumov-Gerasimenko, which passed its last perihelion on 18 August 2002 and was well observed from fall 2002 to spring 2003. Its most prominent feature was a thin dust tail, which is best fitted by the Neck-Line model. Fits of the whole tail provide the dust environment of 67P during a year around perihelion; it shows a strong asymmetry between pre and post perihelion times. The dust mass loss rate appears constant since 2 AU before perihelion at about 200 kg s^-1, a factor 100 higher than 46P/Wirtanen, the previous Rosetta target. Neck-Line photometry during 2002 and 2003 suggests that such a dust environment has remained similar since 3.6 AU before perihelion, i.e. the distance at which Rosetta science operations will start and the lander will be delivered to the surface.