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Accretion and Magnetic Reconnection in the Classical T Tauri Binary DQ Tau

Tofflemire, Benjamin M. and Mathieu, Robert D. and Ardila, David R. and Akeson, Rachel L. and Ciardi, David R. and Johns-Krull, Christopher and Herczeg, Gregory J. and Quijano-Vodniza, Alberto (2017) Accretion and Magnetic Reconnection in the Classical T Tauri Binary DQ Tau. Astrophysical Journal, 835 (1). Art. No. 8. ISSN 0004-637X. https://resolver.caltech.edu/CaltechAUTHORS:20170120-090229795

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Abstract

The theory of binary star formation predicts that close binaries (a < 100 au) will experience periodic pulsed accretion events as streams of material form at the inner edge of a circumbinary disk (CBD), cross a dynamically cleared gap, and feed circumstellar disks or accrete directly onto the stars. The archetype for the pulsed accretion theory is the eccentric, short-period, classical T Tauri binary DQ Tau. Low-cadence (~daily) broadband photometry has shown brightening events near most periastron passages, just as numerical simulations would predict for an eccentric binary. Magnetic reconnection events (flares) during the collision of stellar magnetospheres near periastron could, however, produce the same periodic, broadband behavior when observed at a one-day cadence. To reveal the dominant physical mechanism seen in DQ Tau's low-cadence observations, we have obtained continuous, moderate-cadence, multiband photometry over 10 orbital periods, supplemented with 27 nights of minute-cadence photometry centered on four separate periastron passages. While both accretion and stellar flares are present, the dominant timescale and morphology of brightening events are characteristic of accretion. On average, the mass accretion rate increases by a factor of five near periastron, in good agreement with recent models. Large variability is observed in the morphology and amplitude of accretion events from orbit to orbit. We argue that this is due to the absence of stable circumstellar disks around each star, compounded by inhomogeneities at the inner edge of the CBD and within the accretion streams themselves. Quasiperiodic apastron accretion events are also observed, which are not predicted by binary accretion theory.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.3847/1538-4357/835/1/8DOIArticle
http://iopscience.iop.org/article/10.3847/1538-4357/835/1/8/metaPublisherArticle
https://arxiv.org/abs/1612.02431arXivDiscussion Paper
ORCID:
AuthorORCID
Akeson, Rachel L.0000-0001-9674-1564
Ciardi, David R.0000-0002-5741-3047
Herczeg, Gregory J.0000-0002-7154-6065
Additional Information:© 2017 The American Astronomical Society. Received 2016 September 24; revised 2016 November 28; accepted 2016 November 29; published 2017 January 16. The authors would like to thank Diego Muñoz and Dong Lai for providing the results of their simulations and for many useful discussions. We thank Suzanne Hawley and the Astrophysical Research Consortium (ARC) for their generous allocation of ARCSAT commissioning time as well as Flynn Hasse and the WIYN 0.9 m synoptic observers, Stephen Gilliam, François Dufour, and William Romanishin. This work makes use of observations from the LCOGT network and observations obtained with Apache Point Observatory's 0.5 m Astrophysical Research Consortium Small Aperture Telescope. B.M.T. acknowledges support from a Sigma Xi Grant-in-Aid of Research and the University of Wisconsin–Madison Graduate School.
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
Sigma XiUNSPECIFIED
University of WisconsinUNSPECIFIED
Subject Keywords:accretion, accretion disks – binaries: close – stars: individual (DQ Tau) – stars: formation
Issue or Number:1
Record Number:CaltechAUTHORS:20170120-090229795
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170120-090229795
Official Citation:Benjamin M. Tofflemire et al 2017 ApJ 835 8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73564
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:22 Jan 2017 17:11
Last Modified:03 Oct 2019 16:29

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