Discovery of Molecular Hydrogen Emission from the TWA 7 Debris Disk
Abstract
We have analyzed archival HST+COS spectra of the young star TWA 7 and have discovered warm molecular hydrogen that we interpret as arising from this stars low mass debris disk. TWA 7, a ~9 Myr old M2 weak-lined T Tauri star, has a well studied cold debris disk, and the star has previously shown no signs of accretion. While molecular hydrogen can be produced in star spots of cool stars such as TWA 7, the H2 line ratios we detect indicate that the molecular hydrogen we observe comes from the disk and is excited by Ly-alpha emission produced by very low levels of accretion from the disk. The H2 we detect is expected to be produced by gas that is significantly warmer than the CO previously detected in this disk, and so is likely much closer to the star, likely in the terrestrial planet forming region. Molecular hydrogen detections in debris disks are rare, making TWA 7 fairly unique. We estimate the column density of the molecular hydrogen and discuss its potential origins in more detail.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23530822J