A Surprising Dynamical Mass for V773~Tau~B

Abstract

We report on new high-resolution imaging and spectroscopy on the multiple T Tauri star system V773 Tau over the 2003 -- 2009 period. With these data we derive relative astrometry, photometry between the A and B components, and radial velocity (RV) of the A-subsystem components. Combining these new data with previously published astrometry and RVs, we update the relative A-B orbit model. This updated orbit model, the known system distance, and A subsystem parameters yields a dynamical mass for the B component for the first time. Remarkably the derived B dynamical mass is in the range of 1.7 -- 3.0 M$_\sun$. This is much higher than previous estimates, and suggests that like A, B is also a multiple stellar system. Among these data, spatially-resolved spectroscopy provide new insight into the nature of the B component. Similar to A, these near-IR spectra indicate that the dominant source in B is of mid-K spectral type. If B is in fact a multiple star system as suggested by the dynamical mass estimate, the simplest assumption is that B is composed of similar $\sim$ 1.2 M$_\sun$ PMS stars in a close ($<$ 1 AU) binary system. This inference is supported by line-shape changes in near-IR spectroscopy of B, tentatively interpreted as changing RV among components in V773 Tau B. Relative photometry indicate that B is highly variable in the near-IR. The most likely explanation for this variability is circum-B material resulting in variable line-of-sight extinction. The distribution of this material must be significantly affected by both the putative B multiplicity, and the A-B orbit.

22 pages, 7 figures, accepted for publication ApJ. Companion paper to R. Torres et al arXiv:1112.0114. Table 2 (RV Data Table) to appear in on-line version

References in corpus (8)

• Comparative statistics and origin of triple and quadruple stars
• VLBA determination of the distance to nearby star-forming regions V. Dynamical mass, distance and radio structure of V773 Tau A
• Synchrotron emission from the T Tauri binary system V773 Tau A
• Interacting coronae of two T Tauri stars: first observational evidence for solar-like helmet streamers
• Dynamical Masses for Pre-Main Sequence Stars: A Preliminary Physical Orbit for V773 Tau A
• Geometrical and Physical Properties of Circumbinary Discs in Eccentric Stellar Binaries
• The circumbinary disk of HD 98800 B: Evidence for disk warping
• HD 98800: A most unusual debris disc

Cited by in corpus (10)

• The Gould's Belt Distances Survey (GOBELINS). IV. Distance, Depth and Kinematics of the Taurus Star-Forming Region
• VLBA determination of the distance to nearby star-forming regions V. Dynamical mass, distance and radio structure of V773 Tau A
• Herschel/PACS Survey of protoplanetary disks in Taurus/Auriga -- Observations of [OI] and [CII], and far infrared continuum
• A Disk-based Dynamical Mass Estimate for the Young Binary V4046 Sgr
• Internal and relative motions of the Taurus and Ophiuchus star-forming regions
• The Taurus Boundary of Stellar/Substellar (TBOSS) Survey I: far-IR disk emission measured with Herschel
• The eclipse of the V773 Tau B circumbinary disk
• A Search for Spatially Resolved Infrared Ro-Vibrational Molecular Hydrogen Emission from the Disks of Young Stars
• Dynamical Masses of Young Stars II: Young Taurus Binaries Hubble~4, FF~Tau, and HP~Tau/G3
• RX J0513.1+0851 AND RX J0539.9+0956: Two Young, Rapidly Rotating, Spectroscopic Binary Stars