Molecular Composition and Chemistry of Isolated Dense Cores

Details Molecular Composition and Chemistry of Isolated Dense Cores Molecular Composition and Chemistry of Isolated Dense Cores

Jun 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005sptz.prop20604b&link_type=abstract

Spitzer Proposal ID #20604

Other

Scientific paper

The composition of molecular clouds and the envelopes and disks surrounding low mass protostars within them is still poorly known. There is little doubt that a large fraction of the molecules is frozen on grains, but the abundance of several crucial species (e.g. NH3, CH3OH, ions) in the ices is still highly uncertain. In addition, prominent spectral features discovered decades ago are still not securely identified (e.g. the 6.85 micron absorption band). Gas phase and grain surface chemistry play pivotal roles in molecule formation, but numerous other processes could have significant impacts as well: shocks, thermal heating, irradiation of ices by ultraviolet photons and cosmic rays. Complex species could be formed this way, profoundly influencing cloud, disk, and planetary/cometary chemistry. We propose to obtain Spitzer/IRS spectra of an unprecedented sample of sight-lines tracing dense isolated cores. These cores physically differ from the large, cluster-forming molecular clouds (Ophiuchus, Perseus) that are commonly studied: they are less turbulent, colder, less dense, and likely longer lived. These IRS spectra of isolated cores will thus provide unique information on the ice formation and destruction mechanisms. For example, the longer survival time of ices in these cores might promote the energetic formation of more complex species. Variations in the 6.85 um absorption band may elucidate its carrier. The CO2 band will reflect variations in H and O chemistry as well as thermal history. In an unbiased sample of 66 isolated cores imaged with IRAC/MIPS by the "c2d" Legacy program, we found 30 mostly new protostars. Toward the same cores we selected 33 highly extincted background stars as well, tracing the quiescent cloud medium against which the (processed?) ices around protostars can be contrasted. With this unique source sample it is possible to address the most fundamental questions in astrochemistry: what is the composition of the interstellar medium and how are complex molecules formed?

Affiliated with

Also associated with

No associations

Rating

Molecular Composition and Chemistry of Isolated Dense Cores 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 Molecular Composition and Chemistry of Isolated Dense Cores, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Molecular Composition and Chemistry of Isolated Dense Cores will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1167421