Spitzer Mid-infrared Spectroscopy of Ices Toward Extincted Background Stars

Details Spitzer Mid-infrared Spectroscopy of Ices Toward Extincted Background Stars Spitzer Mid-infrared Spectroscopy of Ices Toward Extincted Background Stars

2005-11-15

arxiv.org/abs/astro-ph/0511467v1

Astrophys.J.635:L145-L148,2005

Astronomy and Astrophysics

Astrophysics

4 pages, 5 figures; To appear in Astrophysical Journal Letters

Scientific paper

10.1086/499584

A powerful way to observe directly the solid state inventory of dense molecular clouds is by infrared spectroscopy of background stars. We present Spitzer/IRS 5-20 micron spectra of ices toward stars behind the Serpens and Taurus molecular clouds, probing visual extinctions of 10-34 mag. These data provide the first complete inventory of solid-state material in dense clouds before star formation begins. The spectra show prominent 6.0 and 6.85 micron bands. In contrast to some young stellar objects (YSOs), most (~75%) of the 6.0 micron band is explained by the bending mode of pure water ice. In realistic mixtures this number increases to 85%, because the peak strength of the water bending mode is very sensitive to the molecular environment. The strength of the 6.85 micron band is comparable to what is observed toward YSOs. Thus, the production of the carrier of this band does not depend on the energetic input of a nearby source. The spectra show large abundances of carbon monoxide and carbon dioxide (20-40% with respect to water ice). Compared to YSOs, the band profile of the 15 micron carbon dioxide bending mode lacks the signatures of crystallization, confirming the cold, pristine nature of these lines of sight. After the dominant species are removed, there are residuals that suggest the presence of minor species such as formic acid and possibly ammonia. Clearly, models of star formation should begin with dust models already coated with a fairly complex mixture of ices.

Affiliated with

Also associated with

No associations

Rating

Spitzer Mid-infrared Spectroscopy of Ices Toward Extincted Background Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Spitzer Mid-infrared Spectroscopy of Ices Toward Extincted Background Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spitzer Mid-infrared Spectroscopy of Ices Toward Extincted Background Stars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-580485