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Title: ACCRETION AND MAGNETIC RECONNECTION IN THE CLASSICAL T TAURI BINARY DQ TAU

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 amplitudemore » 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.« less

Authors:
;  [1];  [2]; ;  [3];  [4];  [5];  [6]
  1. Department of Astronomy, University of Wisconsin–Madison, 475 North Charter Street, Madison, WI 53706 (United States)
  2. The Aerospace Corporation, M2-266, El Segundo, CA 90245 (United States)
  3. NASA Exoplanet Science Institute, IPAC/Caltech, Pasadena, CA 91125 (United States)
  4. Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)
  5. The Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China)
  6. University of Nariño Observatory, Pasto, Nariño (Colombia)
Publication Date:
OSTI Identifier:
22663245
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 835; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BINARY STARS; COLLISIONS; COMPUTERIZED SIMULATION; MAGNETIC RECONNECTION; MASS; ORBITS; PERIODICITY; PHOTOMETRY; PULSES; STELLAR FLARES; STELLAR MAGNETOSPHERES; STREAMS

Citation Formats

Tofflemire, Benjamin M., Mathieu, Robert D., Ardila, David R., Akeson, Rachel L., Ciardi, David R., Johns-Krull, Christopher, Herczeg, Gregory J., and Quijano-Vodniza, Alberto. ACCRETION AND MAGNETIC RECONNECTION IN THE CLASSICAL T TAURI BINARY DQ TAU. United States: N. p., 2017. Web. doi:10.3847/1538-4357/835/1/8.
Tofflemire, Benjamin M., Mathieu, Robert D., Ardila, David R., Akeson, Rachel L., Ciardi, David R., Johns-Krull, Christopher, Herczeg, Gregory J., & Quijano-Vodniza, Alberto. ACCRETION AND MAGNETIC RECONNECTION IN THE CLASSICAL T TAURI BINARY DQ TAU. United States. doi:10.3847/1538-4357/835/1/8.
Tofflemire, Benjamin M., Mathieu, Robert D., Ardila, David R., Akeson, Rachel L., Ciardi, David R., Johns-Krull, Christopher, Herczeg, Gregory J., and Quijano-Vodniza, Alberto. Fri . "ACCRETION AND MAGNETIC RECONNECTION IN THE CLASSICAL T TAURI BINARY DQ TAU". United States. doi:10.3847/1538-4357/835/1/8.
@article{osti_22663245,
title = {ACCRETION AND MAGNETIC RECONNECTION IN THE CLASSICAL T TAURI BINARY DQ TAU},
author = {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},
abstractNote = {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.},
doi = {10.3847/1538-4357/835/1/8},
journal = {Astrophysical Journal},
number = 1,
volume = 835,
place = {United States},
year = {Fri Jan 20 00:00:00 EST 2017},
month = {Fri Jan 20 00:00:00 EST 2017}
}