An Extinction Study of the Taurus Dark Cloud Complex
H. éctorG. Arce, A. A. Goodman;
ApJ, 1999, 517, 264
ABSTRACT:We present a study of the detailed distribution of extinction in a region of the Taurus dark cloud complex.
Our study uses new BVR images of the
region, spectral classification data for 95 stars, and IRAS Sky Survey Atlas
(ISSA) 60 and 100 μm images.
We study the extinction of the region in four
different ways, and we present the first intercomparison of all these methods,
which are as follows: (1) using the color excess of background stars for which
spectral types are known, (2) using the ISSA 60 and 100 μm images, (3) using
star counts, and (4) using an optical (V and R) version of the average color
excess method used by Lada et al.
We find that all four methods give generally
similar results-with important exceptions.
As expected, all the methods
show an increase in extinction due to dense dusty regions (i.e., dark clouds
and IRAS cores) and a general increase in extinction with increasing
declination, due to a larger content of dust in the northern regions of the Taurus dark
cloud complex.
Some of the discrepancies between the methods are caused by
assuming a constant dust temperature for each line of sight in the ISSA
extinction maps and not correcting for unexpected changes in the background
stellar population (i.e., the presence of a cluster or Galactic gradients in
the stellar density and average V-R color).
To study the structure in the
dust distribution, we compare the ISSA extinction and the extinction
measured for individual stars.
From the comparison, we conclude that in the
relatively low-extinction regions studied, with 0.9<A_V<3.0 mag (away
from filamentary dark clouds and IRAS cores), there are no fluctuations in
the dust column density greater than 45% (at the 99.7% confidence level),
on scales smaller than 0.2 pc.
We also report the discovery of a
previously unknown open cluster of stars behind the Taurus dark cloud near
R.A.
4^h19^m, decl.
27 deg30' (B1950).
KEYWORDS: ism: dust, extinction, infrared: ism: continuum, ism: individual: name: taurus dark cloud, techniques: photometric, techniques: spectroscopic
CODE: arce99