The close T Tauri binary system V4046 Sgr: Rotationally modulated X-ray emission from accretion shocks
Abstract
We report initial results from a quasi-simultaneous X-ray/optical observing campaign targeting V4046 Sgr, a close, synchronous-rotating classical T Tauri star (CTTS) binary in which both components are actively accreting. V4046 Sgr is a strong X-ray source, with the X-rays mainly arising from high-density (n_e ~ 10^(11-12) cm^(-3)) plasma at temperatures of 3-4 MK. Our multiwavelength campaign aims to simultaneously constrain the properties of this X-ray emitting plasma, the large scale magnetic field, and the accretion geometry. In this paper, we present key results obtained via time-resolved X-ray grating spectra, gathered in a 360 ks XMM-Newton observation that covered 2.2 system rotations. We find that the emission lines produced by this high-density plasma display periodic flux variations with a measured period, 1.22+/-0.01 d, that is precisely half that of the binary star system (2.42 d). The observed rotational modulation can be explained assuming that the high-density plasma occupies small portions of the stellar surfaces, corotating with the stars, and that the high-density plasma is not azimuthally symmetrically distributed with respect to the rotational axis of each star. These results strongly support models in which high-density, X-ray-emitting CTTS plasma is material heated in accretion shocks, located at the base of accretion flows tied to the system by magnetic field lines.
Cite
@article{arxiv.1204.0964,
title = {The close T Tauri binary system V4046 Sgr: Rotationally modulated X-ray emission from accretion shocks},
author = {C. Argiroffi and A. Maggio and T. Montmerle and D. P. Huenemoerder and E. Alecian and M. Audard and J. Bouvier and F. Damiani and J. -F. Donati and S. G. Gregory and M. Güdel and G. A. J. Hussain and J. H. Kastner and G. G. Sacco},
journal= {arXiv preprint arXiv:1204.0964},
year = {2015}
}
Comments
paper accepted by ApJ