Radio monitoring of 9P/tempel 1 outgassing and gas released by the impact

Abstract

As part of the international observing campaign in support of the NASA Deep Impact mission to comet 9P/Tempel 1, we conducted a monitoring of its outgassing at radio wavelengths. OH observations conducted at the Nançay radio telescope provided a 4-month monitoring of the comet from March to July, followed by the observation of H 2O with the Odin satellite from June to August 2005. The peak of outgassing was found to be around 10 28 molec. s -1 between May and July. Observations of HCN conducted with the IRAM 30 m radio telescope in May 2005 showed a variation of the production rate with a period of 1.73±0.10 days, consistent with the rotation period of the nucleus. The Odin satellite also monitored nearly continuously the H 2O line at 557 GHz during the 38 h following the impact on the 4th of July. Once possible periodic variations related to the nucleus rotation are removed, a small increase of outgassing related to the impact is present, which corresponds to the release of 5000±2000 tons of water. Two other bursts of activity were seen on 23 June and 7 July. ©2009 Springer-Verlag Berlin Heidelberg.