TY - JOUR
T1 - The Close T Tauri Binary System V4046 Sgr: Rotationally Modulated X-Ray Emission from Accretion Shocks
AU - Argiroffi, C.
AU - Maggio, A.
AU - Montmerle, T.
AU - Huenemoerder, D. P.
AU - Alecian, E.
AU - Audard, M.
AU - Bouvier, J.
AU - Damiani, F.
AU - Donati, J. -F.
AU - Gregory, S. G.
AU - Güdel, M.
AU - Hussain, G. A. J.
AU - Kastner, J. H.
AU - Sacco, G. G.
PY - 2012/6
Y1 - 2012/6
N2 - 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.
AB - 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.
KW - : accretion, accretion disks
KW - stars: individual (V4046 Sgr)
KW - stars: magnetic field
KW - stars: pre-main sequence
KW - stars: variables: T Tauri, Herbig Ae/Be
KW - X-rays: stars
UR - https://ui.adsabs.harvard.edu/abs/2012ApJ...752..100A/abstract
U2 - 10.1088/0004-637X/752/2/100
DO - 10.1088/0004-637X/752/2/100
M3 - Article
SN - 0004-637X
VL - 752
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 100
ER -