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Anomalous Spectral Types and Intrinsic Colors of Young Stars

Published online by Cambridge University Press:  27 January 2016

Mark J. Pecaut
Mark J. Pecaut*
Affiliation:
Rockhurst University, 1100 Rockhurst Rd., Kansas City, MO 64110 email: mark.pecaut@rockhurst.edu
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Abstract

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We highlight differences in spectral types and intrinsic colors observed in pre-main sequence (pre-MS) stars. Spectral types of pre-MS stars are wavelength-dependent, with near-infrared spectra being 3-5 spectral sub-classes later than the spectral types determined from optical spectra. In addition, the intrinsic colors of young stars differ from that of main-sequence stars at a given spectral type. We caution observers to adopt optical spectral types over near-infrared types, since Hertzsprung-Russell (H-R) diagram positions derived from optical spectral types provide consistency between dynamical masses and theoretical evolutionary tracks. We also urge observers to deredden pre-MS stars with tabulations of intrinsic colors specifically constructed for young stars, since their unreddened colors differ from that of main sequence dwarfs. Otherwise, V-band extinctions as much as ~0.6 mag erroneously higher than the true extinction may result, which would introduce systematic errors in the H-R diagram positions and thus bias the inferred ages.

Keywords

stars: pre-main sequencestars: fundamental parametersstarspotsopen clusters and associations: individual (η Cha Cluster, TW Hydra Association, β Pictoris moving group, Tucana-Horologium moving group)
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 10 , Issue S314: Young Stars & Planets Near the Sun , November 2015 , pp. 85 - 90
Copyright
Copyright © International Astronomical Union 2016 

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