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. The Astrophysical Journal, 835 (1). ISSN 0004-637X

[img]
Preview
Text (Published Version)
Ciardi_2017_PV.pdf

Download (2311Kb) | Preview

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.


Statistics for USQ ePrint 32081
Statistics for this ePrint Item
Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: No Faculty
Date Deposited: 08 Nov 2017 01:12
Last Modified: 19 Apr 2018 00:33
Uncontrolled Keywords: accretion; accretion disks; binaries; close; stars; formation supporting material; data behind figure; stars; individual(DQ Tau)
Fields of Research : 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020107 Mesospheric, Ionospheric and Magnetospheric Physics
Identification Number or DOI: 10.3847/1538-4357/835/1/8
URI: http://eprints.usq.edu.au/id/eprint/32081

Actions (login required)

View Item Archive Repository Staff Only