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| EPoS Contribution |
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Gas in circumstellar disks of HAeBes
Claire Martin-Zaidi Laboratoire d'Astrophysique de Grenoble, Grenoble, France | |
| Disks around young stars are a natural outcome of the star formation process and the place for planet formation. At the present time, significant effort has been put into the study of the dust in disks. However, the dust only represents a tiny fraction of the disk mass (~1%), and it is thus mandatory to deeply study the gas phase in disks in order to set stronger constraints on the giant planets formation process. Molecular hydrogen (H2) is the most abundant molecule in the circumstellar (CS) environments of young stars and is supposed to be the key element of giant planet formation; thus its diagnostics are promising. Indeed, the detection of H2 provides the most direct information about the gaseous content of disks, setting limits on the timescales for the dissipation of CS matter and possibly planet building. Molecular hydrogen has been observed in CS environments at ultraviolet and near-infrared wavelengths. These observations trace hot CS gas, or gas excited by fluorescent processes, or require specific spatial distributions for the gas to be detectable. They are therefore difficult to translate into gas masses. The pure rotational mid-infrared H2 lines are useful probes because the level populations are expected to be in local thermodynamic equilibrium at the local gas temperature, and so line ratios allow the determination of the excitation temperature and mass of the warm gas. Here, I will present here a review of high-resolution spectroscopic mid-infrared observations of the pure rotational lines of H2, as a tracer of warm gas in the surface layers of circumstellar disks around Herbig Ae/Be stars with the VLT Imager and Spectrometer for the mid-InfraRed (VISIR). | |
| Collaborators: J-.C. Augereau, LAOG, France F. Menard, LAOG, France J. Olofsson, Heidelberg, Germany C. Pinte, LAOG, France E. Habart, IAS, France A. Carmona, ISDC, Switzerland |
Key publication
Suggested Session: Early Phases of Disks |