The Relation of H2 Gas and Dust in Disks of Accreting Stars
First Author:
Laura Ingleby
Email: lingleby AT umich.edu
University of Michigan
1010 Dennison
500 Church St.
Ann Arbor, MI 48109 USA
Abstract
Although detailed studies of the gas and dust in the inner disks around low mass pre- main sequence objects exist, the relationship between the gas and dust in those disks is still unknown. To study this relationship we examine the properties of gas in the Far UV (FUV), where recent observations have revealed the presence of H2 lines excited by Ly alpha fluorescence, which are produced in the inner disk gas. We compare these properties to those of the dust, by examining the slope of the spectral energy distribution in the Spitzer/IRS range, which is a diagnostic of dust settling. With increased settling, the optical depth to high energy photons in the disk decreases and the gas is heated, so we expect H2 emission to increase with settling. We present and analyze Advanced Camera for Surveys (ACS) FUV data of 15 classical T Tauri stars (CTSSs) and Space Telescope Imaging Spectrograph (STIS) data of 4 additional CTTSs in the Taurus molecular cloud. In addition, we have Spitzer IRS spectra and IRAC photometry of each of these sources, resulting in FUV through mid-IR coverage of 19 CTTSs; a range of wavelengths important for studying both the gas and dust in the disk. We analyze the properties of the gas and dust for these sources and discuss how these properties relate to each other.
