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Paper: TEXES Observations of Molecular Hydrogen Emission from AB Aurigae
Volume: 352, New Horizons in Astronomy: Frank N. Bash Symposium 2005
Page: 229
Authors: Bitner, M.A.; Richter, M.J.; Lacy, J.H.; Jaffe, D.T.; Kessler-Silacci, J.E.; Greathouse, T.K.; Blake, G.A.
Abstract: We have used TEXES, the Texas Echelon-cross-Echelle Spectrograph on the NASA Infrared Telescope Facility (IRTF) to search for pure rotational H2 emission from young stars with disks. From the ground, three pure rotational transitions of molecular hydrogen are accessible: J = 6–4 (λ = 8.025 μm), J = 4–2 (λ = 12.27 μm), and J = 3–1 (λ = 17.035 μm). Thus far, studies of gas in protoplanetary disks have focused on either small radii using near-infrared CO observations 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 (1-10 AU). 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 ≈ 60,000 for J = 3–1 and R ≈ 80,000 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 Aurigae, we have detected J = 4–2 emission with FWHM of 7 km s±1. Assuming an inclination of 20° and a stellar mass of 2.5 MSolar centers the emission at ≈ 16 AU in the disk.
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