Cool Stars 14 - Submitted Abstract # 53
This version created on 05 October 2006

Periodic accretion from a circumbinary disk in the young binary UZ
Tauri E


Saurav Dhital, Vanderbilt University, Swarthmore College
Eric L. N. Jensen, Swarthmore College
Keivan Stassun, Vanderbilt University
Jenny Patience, Caltech
Bill Herbst, Wesleyan University
Fred Walter, State University of New York, Stony Brook
Michal Simon, State University of New York, Stony Brook
Gibor Basri, University of California, Berkeley

Most close, young binary stars are surrounded by circumbinary disks.
However, unlike single stars, the nature and extent of the flow of
material from the circumbinary disk to the circumstellar system is not
clear.  Theoretical simulations predict that the gravitational
perturbation of the stars causes the circumbinary material to accrete
onto the circumstellar environment (Artymowicz & Lubow 1996),
manifested as changes in brightness modulated at the binary orbital
period.  We report BVRI photometry over three years for a pre-main
sequence spectroscopic binary UZ Tauri E.  We find that the system's
brightness is clearly periodic, with a best-fit period of 19.17 ± 0.05
days.  This is consistent with the binary orbital period of 19.13
days, re-determined from analysis of new and existing radial velocity
data.  The system shows significant random variability, as seen in
other T Tauri stars.  There is also a general long-term increase in
brightness.  But the overall pattern is periodically recurring
brightening events, spanning more than half an orbital period.  These
results are in accordance with theoretical predictions for binary
systems similar to UZ Tau E.  Along with the pulsed accretion seen in
DQ Tau (Mathieu et al.  1997), our observations indicate that there is
accretion from circumbinary disks, which would possibly increase the
life of circumstellar disks and the timescale for planet formation.

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