Models of Chemistry, Thermal Balance and Infrared Spectra from Intermediate-Aged Disks around G and K stars

Abstract

We model gas and dust emission from regions 0.3-20 AU from a central low mass star in intermediate-aged(~10Myr) disks with optically thin dust. The models treat thermal balance and chemistry self-consistently and calculate the vertical density temperature structure of the gas in a disk. The gas and dust temperatures are calculated separately. We focus on IR gas emission lines and find that the [SI]25.23 micron line is the strongest emission line for a wide range of disk and stellar parameters, followed by emission from [SiII]34.8 um, [FeII]26 um and [OI]63um. [FeI]24um and rotational lines of OH and H2O are strong when gas masses are high (>0.1 M_J). Emission from the rotational lines of H2 is difficult to detect, unless disk gas masses are substantial (>0.1 M_J).