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G.W. Doppmann, T.P. Greene (NASA Ames Research Center), C.J. Lada (CfA Harvard), K.R. Covey (University of Washington)
Infrared observations of heavily embedded protostars in star forming regions provide a crucial window for examining the earlier stages of protostellar evolution, where optical techniques fail because of high extinction (av ~ 50). At high spectral resolution (R > 10,000), photospheric lines originating in the atmospheres of cool (T < 5200 K) protostars are fully resolved and contain physical information about the star and its circumstellar environment, independent of uncertainties in the distance to the cloud and the amount of extinction along the line-of-sight. We present a sample of NIRSPEC/Keck spectra of Class I and flat spectrum (Class I.5) protostars in Ophiuchus, Taurus, and Serpens. Using a new spectral fitting technique that employs spectral synthesis models at high resolution, we fit multiple absorption lines present in K band spectra to determine important physical properties of these embedded protostars. In particular, our near-IR spectroscopic measurements at high resolution (R = 17,500) permit measurements of (1) precise radial velocities (sigmav < 3 km s-1) from line shifts, (2) vsin i rotational velocities from the broadened line widths, (3) effective temperatures and surface gravities from the relative line strengths, and (4) measurements of the continuum veiling by hot dust from the diminished line depths. With these derived properties we place these objects on the H-R diagram for comparison with theoretical evolutionary model tracks to obtain masses and ages, set constraints on the short period binary fraction at earlier evolutionary stages, and explore how rotation and disk accretion relates to earlier protostellar evolutionary states.
Support by the National Research Council is gratefully acknowledged.
The author(s) of this abstract have provided an email address for comments about the abstract: gdoppmann@mail.arc.nasa.gov
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.