Organic volatiles and water in eight Oort cloud comets were investigated at infrared wavelengths. The detected species include H2O, CO, CH3OH, CH4, C2H2, C2H6, OCS, HCN, NH3, and H2CO. Several daughter fragments (CN, OH, NH2, etc.) are also measured. OH prompt emission provides a useful 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). Their low formation temperatures (∼ 30K) 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.
|Original language||English (US)|
|Number of pages||10|
|Journal||European Space Agency, (Special Publication) ESA SP|
|State||Published - Jul 2002|
All Science Journal Classification (ASJC) codes
- Aerospace Engineering
- Space and Planetary Science