Detection of Parent Volatiles in 9P/Tempel-1 during the Deep Impact event.
Detection of Parent Volatiles in 9P/Tempel-1 during the Deep Impact event.


M. J. Mumma, M. A.DiSanti, B. P. Bonev, H. Kawakita, K. Magee-Sauer, N. Dello Russo, S. Sugita, G. Villanueva, E. Gibb, J. Lyke, R.Campbell, J. Aycock, A. Conrad, and F. Chaffee report:

We observed comet 9P/Tempel-1 on UT 4.3 July 2005 using the NIRSPEC high dispersion infrared spectrometer at the Keck-2 telescope on Mauna Kea, Hawaii. Spectral acquisition began at 05:22 UT (30 minutes before impact) and continued until 8:10 UT. Acquired spectra cover the wavelength range 2.9-5.0 um at resolving power l/dl ~ 24,000. The IR continuum began to brighten immediately after impact, and brightening continued for the next hour. Spectral lines of H2O appeared almost immediately, and continued to brighten thereafter. The first instrument setting (28 minutes on source) revealed spectral lines of H2O (7 hot-band lines)), C2H6 (5 Q-branches: RQ2, RQ1, RQ0, PQ1, and PQ2), and CH3OH (many lines). The second setting (24 minutes on source) yielded additional hot-band lines of H2O,along with lines of HCN (six lines), C2H2 (tentatively two lines),CH3OH (many lines) and OH prompt emission. The third setting (14 minutes on source) tested CO and H2O; they are still being reduced. Preliminary reductions provide rotational temperatures for H2O (~ 40 K) and HCN (~ 50 K). The preliminary production rate for HCN is 5x10^25 s^-1 and for C2H6 it is 1x10^26 s^-1, assuming Trot = 50 K. The spectra differ dramatically from those acquired on UT 3 June 2005 with the same instrument.