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Carbon Monoxide Outgassing from Comet P/Schwassmann-Wachmann 1.

J. Crovisier, N. Biver, D. Bockelée-Morvan, P. Colom, L. Jorda, E. Lellouch, G. Paubert, and D. Despois
Observatoire de Paris-Meudon, F-9219 Meudon, France
IRAM, Avenida Divina Pastora, 7, E-18012 Granada, Spain
Observatoire de Bordeaux, BP 89, F-33270 Floirac, France
Abstract: P/Schwassmann-Wachmann 1 is a peculiar comet on a nearly circular orbit at AU from the Sun. It undergoes strong, unpredictable outbursts which cannot be explained by water sublimation at this large heliocentric distance. The recent detection of the line of CO at the JCMT (Senay & Jewitt 1994, Nature 371, 229) suggested that carbon monoxide may be responsible for this activity.

We observed the and lines of CO in comet P/Schwassmann-Wachmann 1 at IRAM 30-m with high spectral resolution at four different epochs. The line profile is dominated by a very narrow (0.14 km sec FWHM) component blueshifted by 0.48 km sec, with a fainter component redshifted at 0.30 km sec (Fig. 7). We infer that CO is preferentially outgassed from the day side of the nucleus, percolating through a porous mantle of ice or dust rather than sublimating from pure exposed ice. From the line width of the narrow component and from the line intensity ratio of the two lines we estimate cold ( K) kinetic and rotational temperatures. The CO production rate, sec in this distant comet and comparable to that of P/Halley near the Sun, is high enough to explain the release of dust and its activity observed in the visible.
(To be published in ICARUS)

 

 


Figure: The CO observed at the IRAM 30-m telescope in comet P/Schwassmann-Wachmann 1 (average of Sept. 3-4 and Oct. 4-5 1994). The velocity scale is with respect to the comet frame of rest.



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Next: New Preprints Up: Scientific Results Previous: The distorted kinematics



Robert Lucas
Thu Mar 9 12:14:01 MET 1995