Submillimeter wave astronomy satellite observations of comet 9P/Tempel 1

Abstract

We present observations of the 110-101 ortho-water ground-state rotational transition in comet 9P/Tempel 1 made with the NASA Submillimeter Wave Astronomy Satellite (SWAS). The SWAS monitoring covered a 3-month period from June to August 2005 and included observations of the comet's activity during the collision of the Deep Impact spacecraft with the nucleus on 4 July 2005. No excess emission from the material ejected by the impactor was detected and we derive an upper limit of 1.8 × 107 kg on the vaporized water ice. However, the water production rate of the comet shows large natural variations of up to a factor of three throughout the 3-month monitoring period. The total amount of water vaporized between 5 June and 1 September 2005 is 4.5 × 1034 molecules (∼ 1.3 × 109 kg) and we estimate that 9P/Tempel 1 has lost as much as N ∼ 1035 molecules during its 2005 apparition. © 2009 Springer-Verlag Berlin Heidelberg.