Argiroffi, C. and Maggio, A. and Montmerle, T. and Huenemoerder, D. P. and Alecian, E. and Audard, M. and Bouvier, J. and Damiani, F. and Donati, J.-F and Gregory, S. G. and Güdel, M. and Hussain, G. A. J. and Kastner, J. H. and Sacco, G. G. (2012) The Close T Tauri Binary System V4046 Sgr: Rotationally Modulated X-Ray Emission from Accretion Shocks. Astrophysical Journal, 752 (2). Art. No. 100. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20120723-122204894
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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)–10^(12) 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.
|Additional Information:||© 2012 The American Astronomical Society. Received 2011 May 26; accepted 2012 April 4; published 2012 May 31. This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. C.A., A.M., and F.D. acknowledge financial contribution from the agreement ASI-INAF I/009/10/0. J.K.’s research on accreting young stars near Earth is supported by National Science Foundation grant AST-1108950 to RIT.|
|Subject 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|
|Official Citation:||The Close T Tauri Binary System V4046 Sgr: Rotationally Modulated X-Ray Emission from Accretion Shocks C. Argiroffi et al. 2012 ApJ 752 100|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Aucoeur Ngo|
|Deposited On:||23 Jul 2012 20:24|
|Last Modified:||26 Dec 2012 15:41|
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