Ice CO-cktails in molecular cloud cores
Abstract
Spectra of the 4.67mu m (2140cm(-1) ) solid-CO absorption feature are presented, towards embedded low mass Young Stellar Objects in nearby molecular cloud cores, mostly in Taurus. The likely composition of the CO-bearing ices is analysed by fitting the observations with laboratory data and the statistical significance of the results is discussed. Excellent fits to the nonpolar component of the CO-ices along the observed lines of sight are produced with irradiated pure CO ices, as previously suggested by Palumbo & Strazzulla (1993). It does not seem to be possible, however, to constrain the composition of the polar component by analysis of the CO band only. The possible origin of the ion irradiation is discussed. The implications of the non-uniqueness of the fit on the determination of the abundance ratio between nonpolar and polar CO-ices are noted. Future observations are suggested to discriminate between the different possibilities for the polar component. Predictions are made for the abundance of CO_2 and methanol in the mantles.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1998
- Bibcode:
- 1998A&A...330..711T
- Keywords:
-
- CIRCUMSTELLAR MATTER;
- STARS: FORMATION;
- STARS: PRE-MAIN SEQUENCE;
- ISM: DUST;
- EXTINCTION;
- ISM: MOLECULES;
- INFRARED: ISM: LINES AND BANDS