Stellar and Circumstellar Properties of the Pre-Main Sequence Binary GV Tau from Infrared Spectroscopy

We report spatially resolved spectroscopy of both components of the lowmass pre-main-sequence binary GV Tau. High resolution spectroscopy in the Kand L-bands is used to characterize the stellar properties of the binary and to explore the nature of the circumstellar environment. We find that the southern component, GV Tau S, is a radial velocity variable, possibly as a result of an unseen low-mass companion. The strong warm gaseous HCN absorption reported previously toward GV Tau S (Gibb et al. 2007) was not present during the epoch of our observations. Instead, we detect warm (∼500 K) molecular absorption with similar properties toward the northern infrared companion, GV Tau N. At the epoch of our observations, the absorbing gas toward GV Tau N was approximately at the radial velocity of the GV Tau molecular envelope, but it was redshifted with respect to the star by ∼13 km s. One interpretation of our results is that GV Tau N is also a binary and that most of the warm molecular absorption arises in a circumbinary disk viewed close to edge-on. Subject headings: infrared: stars – stars: formation, fundamental parameters, late-type, low-mass, pre–main sequence — stars: circumstellar matter, stars: individual (GV Tau)— techniques: spectroscopic, radial velocities Data presented herein were obtained at the W.M. Keck Observatory from telescope time allocated to the National Aeronautics and Space Administration through the agency’s scientific partnership with the California Institute of Technology and the University of California. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. NOAO, 950 North Cherry Avenue, Tucson, AZ 85719 Naval Research Laboratory, Code 7210, Washington, DC 20375