Modeling the gas reservoir of circumstellar disks around young G-type stars

Abstract

Interpretation of molecular line observations in tenuous circumstellar disks around young G-type stars in terms of a disk mass is difficult without a model that describes the chemical structure of these disks. This paper now discusses the chemistry in tenuous disks around young solar-type stars based on disk models that take into account the presence of a stellar chromosphere. The example of the disk around a 70 Myr old solar-type star shows that the dissociating radiation from the chromosphere is stronger than the interstellar ultraviolet radiation field up to a distance of ~400 AU from the star. Similar to other studies in this research field, it is found that, due to photodissociation, the CO-to-H_2 ratio is far from the canonical value of 10^-4 for molecular clouds. Moreover, the dust-to-gas mass ratio, as well as the dust grain size play an important role for the H_2 abundance in these disks.

8 pages, 6 figures, A&A accepted

References in corpus (1)

• Discovery of Reflection Nebulosity Around Five Vega-like Stars

Cited by in corpus (5)

• Dynamics of Protoplanetary Disks
• Photoprocesses in protoplanetary disks
• X-ray irradiated protoplanetary disk atmospheres II: Predictions from models in hydrostatic equilibrium
• GASPS - a Herschel survey of gas and dust in Protoplanetary Disks: Summary and Initial Statistics
• From discs to planetesimals I: evolution of gas and dust discs