GALAXY EVOLUTION EXPLORER OBSERVATIONS OF CS AND OH EMISSION IN COMET 9P/TEMPEL 1 DURING DEEP IMPACT

Galaxy Evolution Explorer (GALEX) observations of comet 9P/Tempel 1 using the near-ultraviolet (NUV) objective grism were made before, during and after the Deep Impact event that occurred on 2005 July 4 at 05:52:03 UT when a 370 kg NASA spacecraft was maneuvered into the path of the comet. The NUV channel provides usable spectral information in a bandpass covering 2000-3400 A with a point source spectral resolving power of R {approx} 100. The primary spectral features in this range include solar continuum scattered from cometary dust and emissions from OH and CS molecular bands centered near 3085 and 2575 A, respectively. In particular, we report the only cometary CS emission detected during this event. The observations allow the evolution of these spectral features to be tracked over the period of the encounter. In general, the NUV emissions observed from Tempel 1 are much fainter than those that have been observed by GALEX from other comets. However, it is possible to derive production rates for the parent molecules of the species detected by GALEX in Tempel 1 and to determine the number of these molecules liberated by the impact. The derived quiescent production rates are Q(H{sub 2}O) = 6.4 x 10{supmore » 27} molecules s{sup -1} and Q(CS{sub 2}) = 6.7 x 10{sup 24} molecules s{sup -1}, while the impact produced an additional 1.6 x 10{sup 32} H{sub 2}O molecules and 1.3 x 10{sup 29} CS{sub 2} molecules, a similar ratio as in quiescent outgassing.« less

[1]  The impact and rotational lightcurves of Comet 9P/Tempel 1 , 2006, astro-ph/0608611.

[2]  D. K. Prinz,et al.  Validation of the UARS solar ultraviolet irradiances: Comparison with the ATLAS 1 and 2 measurements , 1996 .

[3]  Hubble Space Telescope observations of Comet 9P/Tempel 1 during the Deep Impact encounter , 2007 .

[4]  M. Fulle,et al.  Deep impact as a world observatory event : synergies in space, time, and wavelength ; proceedings of the ESO VUB conference held in Brussels, Belgium, 7 - 10 August 2006 , 2009 .

[5]  David G. Schleicher,et al.  Photometry and Imaging Results for Comet 9P/Tempel 1 and Deep Impact: Gas Production Rates, Postimpact Light Curves, and Ejecta Plume Morphology , 2006 .

[6]  M. A’Hearn.  Deep Impact and the Origin and Evolution of Cometary Nuclei , 2008 .

[7]  P. Feldman.  Gas Production by Deep Impact from Far-ultraviolet Observations , 2009 .

[8]  Swift ultraviolet photometry of the Deep Impact encounter with Comet 9P/Tempel 1 , 2007 .

[9]  M. A’Hearn,et al.  Atomic Sulfur in Cometary Comae Based on UV Spectra of the SITriplet near 1814 Å , 1997 .

[10]  S. Debei,et al.  Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta , 2007 .

[11]  Radio observations of Comet 9P/Tempel 1 before and after Deep Impact , 2007 .

[12]  Michael F. A'Hearn,et al.  The fluorescence of cometary OH , 1988 .

[13]  H. Melosh,et al.  Deep Impact: Excavating Comet Tempel 1 , 2005, Science.

[14]  N. Thomas,et al.  A large dust/ice ratio in the nucleus of comet 9P/Tempel 1 , 2005, Nature.

[15]  S. Hasegawa,et al.  Deep Impact: Observations from a Worldwide Earth-Based Campaign , 2005, Science.

[16]  Stephan R. McCandliss,et al.  Carbon Monoxide in Comet 9P/Tempel 1 before and after the Deep Impact Encounter , 2006, astro-ph/0607185.

[17]  P. Feldman,et al.  Ultraviolet imaging spectroscopy of comet Lee (C/1999 H1) with HST/STIS. , 1999 .

[18]  P. Feldman,et al.  Solar Flux Variability and the Lifetimes of Cometary H2O and OH , 1994 .

[19]  David H. Lumb,et al.  Detection of water ice grains after the DEEP IMPACT onto Comet 9P/Tempel 1 , 2006 .