Stable and Unstable Regimes of Mass Accretion onto RW Aur A
Date
2016
Authors
Takami, Michihiro
Wei, Yu-Jie
Chou, Mei-Yin
Karr, Jennifer L.
Beck, Tracy L.
Manset, Nadine
Chen, Wen-Ping
Kurosawa, Ryuichi
Fukagawa, Misato
White, Marc
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Volume Title
Publisher
IOP Publishing
Abstract
We present monitoring observations of the active T Tauri star RW Aur, from 2010 October to 2015 January, using
optical high-resolution (R 10,000) spectroscopy with Canada–France–Hawaii Telescope/ESPaDOnS. Optical
photometry in the literature shows bright, stable fluxes over most of this period, with lower fluxes (by 2–3 mag) in
2010 and 2014. In the bright period our spectra show clear photospheric absorption, complicated variation in the
Ca II λ8542 emission profile shapes, and a large variation in redshifted absorption in the O I λλ7772 and 8446 and
He I λ5876 lines, suggesting unstable mass accretion during this period. In contrast, these line profiles are
relatively uniform during the faint periods, suggesting stable mass accretion. During the faint periods, the
photospheric absorption lines are absent or marginal, and the averaged Li I profile shows redshifted absorption due
to an inflow. We discuss (1) occultation by circumstellar material or a companion and (2) changes in the activity of
mass accretion to explain the above results, together with near-infrared and X-ray observations from 2011 to 2015.
Neither scenario can simply explain all the observed trends, and more theoretical work is needed to further
investigate their feasibilities.
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The Astrophysical Journal
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Journal article
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Open Access
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