AAS 207th Meeting, 8-12 January 2006
Session 9 Circumstellar Disks I
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

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[9.01] TEXES Observations of Molecular Hydrogen Emission from AB Aurigae

M.A. Bitner (University of Texas at Austin), M.J. Richter (University of California, Davis), J.H. Lacy, D.T. Jaffe (University of Texas at Austin), T.K. Greathouse (Lunar and Planetary Institute), J.E. Kessler-Silacci (University of Texas at Austin), G.A. Blake (California Institute of Technology)

We have observed the Herbig Ae star, AB Aur, with TEXES, the Texas Echelon-cross-Echelle Spectrograph (Lacy et al. 2002), on the NASA IRTF to search for molecular hydrogen emission in the mid-infrared. From the ground, three pure rotational transitions of molecular hydrogen are accessible: J=6-4 (\lambda = 8.025 \mum), J=4-2 (\lambda = 12.279 \mum), and J=3-1 (\lambda = 17.035 \mum). To this point, studies of gas in protoplanetary disks have focused on either small radii using near-infrared CO emission as a probe or on large radii with observations in the millimeter wavelength range. Observations of molecular emission in the mid-infrared offer the potential to study gas in disks at intermediate radii (1-10AU). Molecular hydrogen can be a useful probe since it is the dominant constituent in disks and therefore allows for mass determinations which avoid CO/H2 conversion factors. When coupled with knowledge of the stellar mass and inclination, high resolution observations (R\approx60,000 for J=3-1 and R\approx80,000 for J=4-2 and J=6-4) may allow us to study line profiles and determine the radial location of the emission. In the case of AB Aur, we have detected J=4-2 emission with FWHM 7 km s-1. Assuming an inclination of 20\circ and a stellar mass of 2.5 M\sun centers the emission near 16 AU in the disk.

Observations with TEXES are supported by NSF grant AST-0205518.

The author(s) of this abstract have provided an email address for comments about the abstract: mbitner@astro.as.utexas.edu

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