High Resolution Spectroscopy of Infrared CO Emission from Young Stars
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We have obtained high-resolution spectra of the CO band-head emission from five young stars. We find a variety of line shapes, and we compare the profiles with those predicted by models of accretion disks and neutral winds. Standard accretion disks are able to reproduce the fluxes, profiles, and optical depths of our sources, with accretion rates of ~ 10-7 M⊙ yr-1. Winds successfully account for the fluxes and profiles provided the wind does not cool adiabatically, but remains hot at least out to where the density is too low to excite CO emission. However, our wind model predicts optically-thin emission, which is inconsistent with low-resolution data. We therefore prefer disks as the origin of the CO band-head emission in young stars.
Key wordspre-main sequence stars line profiles accretion disks stellar winds
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