Remote infrared observations of parent volatiles in comets: A window on the early solar system
Abstract
Organic volatiles and water in Oort Cloud comets were investigated at infrared wavelengths. The detected species include H 2O, CO, CH 3OH, CH 4, C 2H 2, C 2H 6, OCS, HCN, NH 3, and H 2CO. Several daughter fragments (CN, OH, NH 2, etc.) are also measured, and OH prompt emission provides a proxy for water. Long-slit spectra are taken at high spectral dispersion and high spatial resolution, eliminating several sources of systematic error. The resulting parent volatile production rates are highly robust, permitting a sensitive search for compositional diversity among comets. Here, seven OC comets are compared. Six (including Halley) exhibit similar compositions (excepting CO and CH 4). Their low formation temperatures (∼30 K) suggest this group probably formed beyond 30 AU from the young sun. However, C/1999 S4 is severely depleted in hypervolatiles and also in methanol, and it likely formed near 5-10 AU. C/2001 A2 is discussed briefly to illustrate future prospects.
- Publication:
-
Advances in Space Research
- Pub Date:
- June 2003
- DOI:
- 10.1016/S0273-1177(03)00578-7
- Bibcode:
- 2003AdSpR..31.2563M