Stable and Unstable Regimes of Mass Accretion onto RW Aur A

Abstract

We present monitoring observations of the active T Tauri star RW Aur, from 2010 October to 2015 January, using optical high-resolution (R>10000) spectroscopy with CFHT-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 8542 A emission}profile shapes, and a large variation in redshifted absorption in the O I 7772 and 8446 A and He I 5876 A 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 2011-2015. Neither scenario can simply explain all the observed trends, and more theoretical work is needed to further investigate their feasibilities.

23 pages, 11 figures, 4 tables, accepted by Astrophysical Journal; some typos corrected on 4/18/2016

References in corpus (11)

• Accretion to Magnetized Stars through the Rayleigh-Taylor Instability: Global Three-Dimensional Simulations
• Results of the ROTOR-program. I. The long-term photometric variability of classical T Tauri stars
• Spatially Resolved Molecular Hydrogen Emission in the Inner 200AU Environments of Classical T Tauri Stars
• A kinematic study of the Taurus-Auriga T association
• A tidal encounter caught in the act: modelling a star-disc fly-by in the young RW Aurigae system
• The HD 163296 Circumstellar Disk in Scattered Light: Evidence of Time-Variable Self-Shadowing
• Modelling the magnetic activity & filtering radial velocity curves of young Suns: the weak-line T Tauri star LkCa 4
• Magnetospheric Gap and Accumulation of Giant Planets Close to the Star
• Adaptive Optics Spectroscopy of the [Fe II] Outflows from HL Tauri and RW Aurigae
• Another deep dimming of the classical T Tauri star RW Aur A
• Reverse Rotation of the Accretion Disk in RW Aur A: Observations and a Physical Model

Cited by in corpus (14)

• Multiple Stellar Fly-Bys Sculpting the Circumstellar Architecture in RW Aurigae
• Violent environment of the inner disk of RW Aur A probed by the 2010 and 2015 dimming events
• Analysis of colour and polarimetric variability of RW Aur A in 2010-2018
• The disappearing act: A dusty wind eclipsing RW Aur
• A "Rosetta Stone" for protoplanetary disks: The synergy of multi-wavelength observations
• Star-disk interactions in multi-band photometric monitoring of the classical T Tauri star GI Tau
• Exploring the dimming event of RW Aur A through multi-epoch VLT/X-Shooter spectroscopy
• Optical dimming of RW Aur associated with an iron rich corona and exceptionally high absorbing column density
• Time-Variable Jet Ejections from RW Aur A, RY Tau and DG Tau
• The jet of the young star RW Aur A and related problems
• Interpreting observations of edge-on gravitationally unstable accretion flows
• Modulated accretion in T Tauri star RY Tau -- stable MHD propeller or a planet at 0.2 AU?
• RW Aur B: a modest UX Ori type companion of the famous primary
• Veiling of Photosphere Lines in the Spectra of UX ORI Stars at Deep Light Minima. I. The Star RR Tau