A. Boden, G. Torres, G. Duchene, Q. Konopacky, A. Ghez, R. Torres, L. Loinard
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.
View original:
http://arxiv.org/abs/1112.1018
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