LASP Science Seminars
The Dispersal of Gas in Circumstellar Disks Based on Observations of H_2 in the FUV
Laura Flagg (Cornell University)
Planets form in circumstellar disks. However, the main component of these disks, H_2, is extremely hard to detect. We have developed a new technique that increases our sensitivity to warm H_2 emission in medium resolution FUV spectra taken with HST using COS or STIS by better than a factor of 10. With this new technique, we detect H_2 in the spectra of TWA 7, a ~9 Myr M2 star with a cold debris disk but no clear signs of accretion and show that it likely comes from the debris disk itself, although closer in where the disk is relatively warm. We discuss detections of H_2 from stars without warm dust in Upper Sco. These detections of H_2 in older debris disk systems imply that H_2 may last longer than previous evidence had indicated. We also talk about the confusing presence of H_2 in the AU Mic system and what we learned about the star and its disk from analyzing it.
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