New Molecular Species in Comet C/1995 O1 (Hale-Bopp) Observed with the Caltech Ssubmillimeter Observatory

• Published in: Earth, moon, and planets Vol. 78; no. 1-3; pp. 13 - 20
• Main Authors: Lis, D. C, Mehringer, D. M, Benford, D, Gardner, M, Phillips, T. G, Bockelée-Morvan, D, Biver, N, Colom, P, Crovisier, J, Despois, D, Rauer, H
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.07.1997
• Subjects: Comets; Hale-Bopp comet; Millimeter waves; Observatories; Radio waves; Wavelengths
• ISSN: 0167-9295; 1573-0794
• DOI: 10.1023/A:1006281802554

We present millimeter-wave observations of HNCO, HC3N, SO, NH2CHO, H13CN, and H3O+ in comet C/1995 O1 (Hale-Bopp)obtained in February–April, 1997 with the Caltech Submillimeter Observatory (CSO). HNCO, first detected at the CSO in comet C/1996B2 (Hyakutake), is securely confirmed in comet Hale-Bopp via observations of three rotational transitions. The derived abundance with respect to H2O is (4-13) × 10-4. HC3N, SO, and NH2CHO are detected for the first time in a comet. The fractional abundance of HC3N based on observations of three rotational lines is (1.9 ± 0.2) × 10-4. Four transitions of SO are detected and the derived fractional abundance, (2-8) ×10-3, is higher than the upper limits derived from UV observations of previous comets. Observations of NH2CHO imply a fractional abundance of (1-8) × 10-4. H3O is detected for the first time from the ground. The H13CN (3-2)transition is also detected and the derived HCN/H13CN abundance ratio is 90 ± 15, consistent with the terrestrial12C/13C ratio. In addition, a number of other molecular species are detected, including HNC, OCS, HCO+, CO+, and CN(the last two are first detections in a comet at radio wavelengths).