Cool Stars 14 - Submitted Abstract # 234
This version created on 05 October 2006

The gas-to-dust ratio near stars and protostars in the Taurus
Molecular Cloud


Adrian Glauser, Paul Scherrer Institut
Marc Audard, Observatoire de Geneve
Kevin Briggs, Paul Scherrer Institut
Manuel Guedel, Paul Scherrer Institut
Tracy Huard, Harvard University
Francois Menard, Laboratoire d'Astrophysique de Grenoble
Thierry Montmerle, Laboratoire d'Astrophysique de Grenoble
Deborah Padgett, Spitzer Science Center
Alessandra Telleschi, Paul Scherrer Institut

The gas-to-dust (G/D) mass ratio, amounting to approximately 100  in
the interstellar medium, may be altered in molecular clouds and
circumstellar disks due to dust evaporation, dust settling,
condensation of gas etc.  Measurements of G/D in dense molecular
environments are challenging since they involve strongly extincted
sources of light.  We present a study of measuring G/D along the
line-of-sights toward T Tau stars and protostars.  To estimate G/D, we
interpret the ratios between the gas absorption column densities
measured from X-ray absorption, and optical-to-infrared extinction by
dust, and compare these ratios with interstellar values.
Alternatively, detailed 3-D dust-disk modeling provides the dust
column, although this technique can be used only in exceptional cases
for which high-quality images are available.  Our X-ray absorption
data are derived from a survey of the Taurus region performed with the
XMM-Newton satellite, while the mid-IR and optical data are from large
surveys of the same region performed with the Spitzer Space Telescope
and CFHT, respectively.  Near-IR data have also been added from 2MASS.

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