Infrared Emission from Ionized Gas in Disks
First Author:
David Hollenbach
Email: dhollenbach AT seti.org
SETI Institute
Coauthors:
Gorti, Uma, SETI Institute
Abstract
Young solar mass stars produce relatively high luminosities in EUV (extreme ultraviolet-13.6 eV < hν < 100 eV) and X-ray (hν < 100 eV) photons. These photons heat and ionize the surface of the disk. The EUV photons completely ionize the very top surface region and heat it to about 10,000 K. The X-rays, typically dominated by roughly 1 keV photons, penetrate deeper and heat a partially ionized layer to temperatures greater than about 1000 K. We provide a parameter study of the infrared line spectra produced by ionized species in disks as a function of the EUV and X-ray luminosities, and the EUV spectral shape. Strong lines include [NeII] 12.8 um, [NeIII] 15.6 um, and [ArII] 7.0 um, although we also include estimates of the fine structure lines of [SIII], [SIV], and [OIII] and recombination lines of hydrogen. Comparisons are made with Spitzer data.
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