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American Astronomical Society, Astronomical Journal, (113), p. 1395, 1997

DOI: 10.1086/118354

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Optical Outburst of a Pre-Main-Sequence Object

Journal article published in 1997 by Joao Alves, Lee Hartmann, Cesar Briceno ORCID, Charles J. Lada
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

We present a study of CB34V, a pre-main sequence object that has increased in brightness by ~ 3.7 magnitudes in the red between November 1951 (1951.9) and February 1996 (1996.1). Our data consists of intermediate and high resolution optical spectroscopy as well as optical and near-infrared photometry (BVRIJHK). We find that the color behavior of the CB34V brightness variation is peculiar, corresponding to a gray brightening. We demonstrate that CB34V is a pre-main sequence object embedded in a small molecular cloud by 2.4 visual magnitudes. At optical wavelengths CB34V has a G5 (III-IV) spectral type and is rapidly rotating with a vsini ~ 145 +/- 20 km s(-1) . We estimate a current bolometric luminosity of 7 < LCB34V < 39 (D/kpc)(2) L_sun. If the optical light is stellar in origin, the object's position on the HR diagram implies a stellar mass of ~ 2 M_sun and an age of ~ 1 x 10(6) years. We consider two possible explanations for the observed brightening: 1) a high accretion episode (FU Orionis type) and 2) time variable extinction due to motions of the non-uniform circumstellar environment. Although we favor the latter, CB34V seems difficult to classify into any of the known types of pre-main sequence variability.