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

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. doi:10.1088/0004-637X/752/2/100.

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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.

Item Type:Article
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URLURL TypeDescription
Bouvier, J.0000-0002-7450-6712
Kastner, J. H.0000-0002-3138-8250
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.
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)ASI-INAF I/009/10/0
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
Issue or Number:2
Record Number:CaltechAUTHORS:20120723-122204894
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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.
ID Code:32646
Deposited By: Aucoeur Ngo
Deposited On:23 Jul 2012 20:24
Last Modified:09 Nov 2021 21:28

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