C. Martin-Zaïdi et al 2007 ApJ 666 L117 doi:10.1086/521924
C. Martin-Zaïdi1, P.-O. Lagage1, E. Pantin1 and E. Habart2
Show affiliationsWe present high-resolution spectroscopic mid-infrared observations of the circumstellar disk around the Herbig Ae star HD 97048 with the VLT Imager and Spectrometer for the mid-InfraRed (VISIR). We detect the S(1) pure rotational line of molecular hydrogen (H 2) at 17.035 μm arising from the disk around the star. This detection reinforces the claim that HD 97048 is a young object surrounded by a flared disk at an early stage of evolution. The emitting warm gas is located within the inner 35 AU of the disk. The line-to-continuum flux ratio is much higher than expected from models of disks at local thermodynamic equilibrium. We investigate the possible physical conditions, such as a gas-to-dust mass ratio higher than 100 and different excitation mechanisms of molecular hydrogen (e.g., X-ray heating, shocks), that would explain the detection. We tentatively estimate the mass of warm gas to be in the range from 10-2 to nearly 1 MJup. Further observations are needed to better constrain the excitation mechanisms as well as the mass of gas.
circumstellar matter; infrared: stars; planetary systems: protoplanetary disks; stars: individual (HD 97048); stars: pre-main sequence
Issue 2 (2007 September 10)
Received 2007 July 6, accepted for publication 2007 July 26
Published 2007 August 24
C. Martin-Zaïdi et al 2007 ApJ 666 L117
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