The Close T Tauri Binary System V4046 Sgr: Rotationally Modulated X-Ray Emission from Accretion Shocks

C. Argiroffi, A. Maggio, T. Montmerle, D. P. Huenemoerder, E. Alecian, M. Audard, J. Bouvier, F. Damiani, J. -F. Donati, S. G. Gregory, M. Güdel, G. A. J. Hussain, J. H. Kastner, G. G. Sacco

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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~ 1011-1012 cm-3) plasma at temperatures of 3-4 MK. Our multi-wavelength 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.
Original languageEnglish
Article number100
Number of pages8
JournalAstrophysical Journal
Volume752
Issue number2
DOIs
Publication statusPublished - Jun 2012

Keywords

  • : accretion, accretion disks
  • stars: individual (V4046 Sgr)
  • stars: magnetic field
  • stars: pre-main sequence
  • stars: variables: T Tauri, Herbig Ae/Be
  • X-rays: stars

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    Argiroffi, C., Maggio, A., Montmerle, T., Huenemoerder, D. P., Alecian, E., Audard, M., Bouvier, J., Damiani, F., Donati, J. -F., Gregory, S. G., Güdel, M., Hussain, G. A. J., Kastner, J. H., & Sacco, G. G. (2012). The Close T Tauri Binary System V4046 Sgr: Rotationally Modulated X-Ray Emission from Accretion Shocks. Astrophysical Journal, 752(2), [100]. https://doi.org/10.1088/0004-637X/752/2/100