期刊
ASTROPHYSICAL JOURNAL
卷 752, 期 2, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/752/2/100
关键词
accretion, accretion disks; stars: individual (V4046 Sgr); stars: magnetic field; stars: pre-main sequence; stars: variables: T Tauri, Herbig Ae/Be; X-rays: stars
资金
- ESA Member States
- NASA
- National Science Foundation [AST-1108950]
- [ASI-INAF I/009/10/0]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1108950] Funding Source: National Science Foundation
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) similar to 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.
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