Document Type
Article
Publication Date
7-1-2006
Publication Title
The Astrophyical Journal
Volume
646
Issue
1
Publisher
The American Astronomical Society
Abstract
We present high-resolution infrared spectra of four YSOs (T Tau N, T Tau S, RNO 91, and HL Tau). The spectra exhibit narrow absorption lines of 12CO, 13CO, and C18O, as well as broad emission lines of gas-phase 12CO. The narrow absorption lines of CO are shown to originate from the colder circumstellar gas. We find that the line-of-sight gas column densities resulting from the CO absorption lines are much higher than expected for the measured extinction for each source and suggest the gas/dust ratio is measuring the dust settling and/or grain coagulation in these extended disks. We provide a model of turbulence, dust settling, and grain growth to explain the results.
Recommended Citation
Please use publisher's recommended citation.
Comments
This article has been published in the Astrophysical Journal. Please find the published version here (note that a subscription may be necessary to access this version):
http://iopscience.iop.org/0004-637X/646/1/342
The American Astronomical Society holds the copyright in this article.