S Coronae Australis -- a T Tauri Twin

Abstract

The star S CrA is a tight visual binary consisting of two classical T Tauri stars, both with outstanding spectral characteristics and brightness variations. High-resolution spectra were collected at ESO and photometric observations with the SMARTS telescope. Both stars undergo large variation in brightness caused mainly by variable foreground extinction. From the stellar parameters we conclude that the two stars are remarkably similar, and that S CrA can be regarded as a T Tauri twin. Rotational periods and inclinations are also similar. The stars differ, however, in terms of degree of veiling and emission line profiles. We compared observed Balmer emission line profiles with models including magnetospheric accretion and a disk wind. We found a good match between observed signatures of accreting gas, wind features, and rotational velocities with those resulting from our modelling for inclinations of around 65 degrees. At this orientation the trajectories of infalling gas just above the stellar surfaces are parallel to the line-of-sight, and accordingly we observe extended red-shifted absorption components extending to + 380 km/s, the estimated free-fall velocity at the surface. However, our so derived inclinations differ from those derived from interferometric near-infrared spectroscopy, and we discuss possible causes for this puzzling discrepancy.

11 pages, 12 figures

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Cited by in corpus (6)

• S and VV Corona Australis: Spectroscopic Variability in Two Young Binary Star Systems
• Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Diverse outcomes of binary-disk interactions
• Inhomogeneous dust eclipses in young stars. The case of CQ Tauri
• Modulated accretion in T Tauri star RY Tau -- stable MHD propeller or a planet at 0.2 AU?
• Star-disk interactions in the strongly accreting T Tauri Star S CrA N
• The GRAVITY young stellar object survey XIV : Investigating the magnetospheric accretion-ejection processes in S CrA N