Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1K082

A Spectroscopic Census of the young sigma Orionis cluster

Hernández, Jesús (Centro de Investigaciones de Astronomía, Mérida, Venezuela)
Pérez, Alice (Centro de Investigaciones de Astronomía, Merida, Venezuela)
Calvet, Nuria (Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, US)
Olguin, Lorenzo (Universidad de Sonora, Mexico)
Contreras, Maria E. (UNAM-Ensenada, Mexico)
Briceño, Cesar (Centro de Investigaciones de Astronomía, Mérida, Venezuela)
Allen, Lori (NOAO,USA)
Espaillat, Catherine (Harvard-Smithsonian Center for Astrophysics)

We present a spectroscopic survey of the stellar population of the sigma Orionis cluster. Using low resolution spectra and the SPTCLASS code, we have obtained spectral types for 340 stars. Spectroscopic data for spectral typing come from several spectrographs with similar spectroscopic coverage and resolution. More than half of the stars of our sample are members confirmed by the presence of lithium in absorption, strong Hα line in emission or presence of weak gravity-sensitive features. In addition, we have obtained high resolution (R∼34,000) spectra in the Hα region for 169 stars in the cluster. Radial velocity was calculated from this data set. The radial velocity distribution for members of the cluster is in agreement with previous works. Analysis of the profile of the Hα line and infrared observations reveals two binary candidates or fast rotators that mimic the Hα width expected in stars with accretion disks. On the other hand there are stars with optically thick disks and narrow Hα profiles not expected in accreting stars. This contribution constitutes the largest homogeneous spectroscopic data set to date.

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