Accession Number:

ADA443719

Title:

A New Probe of the Planet-Forming Region in T Tauri Disks

Descriptive Note:

Journal article

Corporate Author:

AEROSPACE CORP LOS ANGELES CA

Report Date:

2004-10-20

Pagination or Media Count:

5.0

Abstract:

We present new observations of the far-ultraviolet FUV 1100 2200 A radiation field and the near- to mid-IR 3-13.5 micron spectral energy distribution SED of a sample of T Tauri stars selected on the basis of bright, molecular disks GM Aur, DM Tau, and LkCa 15. In each source, we find evidence for Ly-alpha-induced H2 fluorescence and an additional source of FUV continuum emission below 1700 A. Comparison of the FUV spectra to a model of H2 excitation suggests that the strong continuum emission is due to electron impact excitation of H2. The ultimate source of this excitation is likely X-ray irradiation that creates hot photoelectrons mixed in the molecular layer. Analysis of the SED of each object finds the presence of inner disk gaps with sizes of a few AU in each of these young 1 Myr stellar systems. We propose that the presence of strong H2 continuum emission and inner disk clearing are related by the increased penetration power of high-energy photons in gas-rich regions with low grain opacity.

Subject Categories:

  • Astronomy
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE