A New Probe of the Planet-Forming Region in T Tauri Disks
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 20, 2004
- Accession Number
- ADA443719
Entities
People
- Chunhua Qi
- David K. Lynch
- Edwin Bergin
- Gregory J. Herczeg
- Herve Abgrall
- Michael L. Sitko
- Nuria Calvet
- Paola D'alessio
- R. B. Perry
- Suellen M. Brafford
Organizations
- The Aerospace Corporation