Cool Stars 14 - Submitted Abstract # 100
This version created on 05 October 2006

Observations of Gas and Dust in Nearby Edge-On Disk Systems


Seth Redfield, University of Texas at Austin
Jacqueline Kessler-Silacci, University of Texas at Austin
Lucas Cieza, University of Texas at Austin

Edge-on debris disks systems provide a unique opportunity to probe the
structure of both the dust and gas in circumstellar environments.
Measurements of the dust can be made using infrared (IR) photometry or
scattered light emission, practically independent of the disk
orientation.  Measurements of the gas content using high resolution
optical and ultraviolet absorption line spectroscopy, however, require
that the star and the plane of the disk lie along the line of sight
(i.e., that the circumstellar disk is edge-on).  We present Spitzer IR
observations and optical absorption line observations of several
stars, suspected of being edge-on disk systems based on short
timescale (~days) gas absorption variability, or nonvariable, but
anomalously large absorption signatures.  The gas absorption line
variability was monitored in CaII and NaI over two years, and
supplementary observations were made of stars proximate to our primary
targets, to untangle any "contaminating" interstellar absorption.
None of our targets show any significant IR excesses.  Presumably, a
reservoir of material is required to replenish the inner gas disk
which is responsible for the observed short timescale absorption line
variability.  Our IR observations provide strong upper limits on the
content of any dust reservoir in these systems.  Together, these
observations probe the relationship between the gas and dust
components of circumstellar disks, and may provide important
constraints on models of disk evolution and planet formation.

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