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Published December 1, 2007 | Published
Journal Article Open

Dynamical Masses for Pre-Main-Sequence Stars: A Preliminary Physical Orbit for V773 Tau A


We report on interferometric and radial velocity observations of the double-lined 51 day period binary (A) component of the quadruple pre-main-sequence (PMS) system V773 Tau. With these observations we have estimated preliminary visual and physical orbits of the V773 Tau A subsystem. Among other parameters, our orbit model includes an inclination of 66.0° ± 2.4° and allows us to infer the component dynamical masses and system distance. In particular, we find component masses of 1.54 ± 0.14 and 1.332 ± 0.097 M_⊙ for the Aa (primary) and Ab (secondary) components, respectively. Our modeling of the subsystem component spectral energy distributions finds temperatures and luminosities consistent with previous studies and, coupled with the component mass estimates, allows for comparison with PMS stellar models in the intermediate-mass range. We compare V773 Tau A component properties with several popular solar composition models for intermediate-mass PMS stars. All models predict masses consistent to within 2 σ of the dynamically determined values, although some models predict values that are more consistent than others.

Additional Information

© 2007 The American Astronomical Society. Received 2007 March 31; accepted 2007 June 15. Part of this work was performed at the Michelson Science Center (MSC), California Institute of Technology under contract with the National Aeronautics and Space Administration (NASA). Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We gratefully acknowledge the support of personnel at the Jet Propulsion Laboratory, W. M. Keck Observatory, and the MSC in obtaining KI observations of V773 Tau A. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The CfA RV observations presented here were originally advocated by Robert Mathieu; we thank him for his gracious contribution of these data in their use here. We thank P. Berlind, M. Calkins, J. Caruso, R. J. Davis, G. Esquerdo, J. Peters, A. Milone, and R. P. Stefanik for obtaining many of the spectroscopic observations. G. T. acknowledges partial support from NASA's MASSIF SIM Key Project (BLF57-04) and NSF grant AST 04-06183. We thank F. D'Antona, J. Montalba´n, S. Stahler, and F. Palla for sharing their pre Y main-sequence evolutionary models and for fruitful discussions on applying them. Thanks also to G. Duchene for sharing IR photometry for V773 Tau A (including his kind permission to report these data here in Table 6) and the anonymous referee, whose many thoughtful comments helped greatly improve this manuscript. This research has made use of services of the MSC at the California Institute of Technology; the SIMBAD database, operated at CDS, Strasbourg, France; NASA's Astrophysics Data System Abstract Service; and data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center, funded by NASA and the National Science Foundation.

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