Stable accretion and episodic outflows in the young transition disk system GM Aurigae

Abstract

We investigate the structure and dynamics of the magnetospheric accretion region and associated outflows on a scale smaller than 0.1 au around the young transitional disk system GM Aur. We monitored the variability of the system on timescales ranging from days to months, using high-resolution optical and near-infrared spectroscopy, multiwavelength photometry, and low-resolution near-infrared spectroscopy, over a total duration of six months (30 rotational cycles). We analyzed the photometric and line profile variability to characterize the accretion and ejection processes. The luminosity of the system is modulated by surface spots at the stellar rotation period of 6.04 days. The Balmer, Paschen, and Brackett hydrogen lines as well as the HeI 5876 A and HeI 10830 A line profiles are modulated on the same period. The PaB line flux correlates with the photometric excess in the u' band, which suggests that most of the line emission originates from the accretion process. High-velocity redshifted absorptions reaching below the continuum periodically appear in the near-infrared line profiles at the rotational phase in which the veiling and line fluxes are the largest. These are signatures of a stable accretion funnel flow and associated accretion shock at the stellar surface. This large-scale magnetospheric accretion structure appears fairly stable over at least 15 and possibly up to 30 rotational periods. In contrast, outflow signatures randomly appear as blueshifted absorption components in the Balmer and HeI 10830 A line profiles and disappear on a timescale of a few days. The coexistence of a stable, large-scale accretion pattern and episodic outflows supports magnetospheric ejections as the main process occurring at the star-disk interface. Stable magnetospheric accretion and episodic outflows appear to be physically linked on a scale of a few stellar radii in this system.

30 pages, 28 figures, 12 tables, accepted for publication in Astronomy & Astrophysics

References in corpus (32)

• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• X-Shooter spectroscopy of young stellar objects in Lupus: Accretion properties of class II and transitional objects
• An Optical Spectroscopic Study of T Tauri Stars. I. Photospheric Properties
• Stellar SEDs from 0.3-2.5 Microns: Tracing the Stellar Locus and Searching for Color Outliers in SDSS and 2MASS
• The Magnetic Fields of Classical T Tauri Stars
• The Stellar Populations of Praesepe and Coma Berenices
• Probing T Tauri Accretion and Outflow with 1 Micron Spectroscopy
• Results of the ROTOR-program. I. The long-term photometric variability of classical T Tauri stars
• Accretion funnels onto weakly magnetized young stars
• SPIRou: nIR velocimetry & spectropolarimetry at the CFHT
• CSI 2264: Probing the inner disks of AA Tau-like systems in NGC 2264
• Modeling T Tauri Winds from He I 10830 Profiles
• APERO: A PipelinE to Reduce Observations -- Demonstration with SPIRou
• The masses of young stars: CN as a probe of dynamical masses
• Redshifted Absorption at He I 10830 as a Probe of the Accretion Geometry of T Tauri Stars
• The magnetic field and accretion regime of CI Tau
• Multi-epoch Ultraviolet HST Observations of Accreting Low-mass Stars
• Constraining the Sub-AU-Scale Distribution of Hydrogen and Carbon Monoxide Gas around Young Stars with the Keck Interferometer
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). IV. Accretion properties of the Taurus-Auriga young association
• A measure of the size of the magnetospheric accretion region in TW Hydrae
• Magnetic braking of accreting T Tauri stars: Effects of mass accretion rate, rotation, and dipolar field strength
• The ODYSSEUS Survey. Motivation and First Results: Accretion, Ejection, and Disk Irradiation of CVSO 109
• Measuring the Density Structure of an Accretion Hot Spot
• Emission-line profile modelling of structured T Tauri magnetospheres
• Using FUV to IR Variability to Probe the Star-Disk Connection in the Transitional Disk of GM Aur
• Rotation Effects in Classical T Tauri Stars
• The magnetic obliquity of accreting T Tauri stars
• A Resolved Near-Infrared Image of The Inner Cavity in The GM Aur Transitional Disk
• Revealing the Star-Disk-Jet Connection in GM Aur using Multiwavelength Variability
• Spectroscopic and interferometric signatures of magnetospheric accretion in young stars

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• Density streams in the disc winds of Classical T Tauri stars