The classical T Tauri spectroscopic binary DQ Tau .2. Emission line variations with orbital phase

被引:74
作者
Basri, G
JohnsKrull, CM
Mathieu, RD
机构
[1] UNIV TEXAS, MCDONALD OBSERV, AUSTIN, TX 78712 USA
[2] UNIV WISCONSIN, DEPT ASTRON, MADISON, WI 53706 USA
关键词
D O I
10.1086/118510
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report on echelle observations of a variety of Line profiles taken throughout the orbit of the close, eccentric binary T Tauri system DQ Tau. The stars themselves exhibit puzzling inconsistencies in the spectral types inferred from atomic versus molecular lines. The system shows clear evidence of an extensive circumbinary disk. The binary is expected to clear a central hole in the disk; however, the line profiles are similar to those from single classical T Tauri stars. This indicates that similar infall and outflow activities are taking place. The implication is that material is flowing through the supposed gap in the disk. It also means that these ''classical'' profiles do not require a stable circumstellar disk for their formation, since the stellar separation at periastron is too small to allow such disks. We present evidence that accretion increases (sometimes dramatically) as the stars approach each other. Both continuum Veiling and emission line intensities can increase. In one outburst the Ca II IR Lines brighten by a factor of 5. We discuss the line profiles during such outbursts in some detail. Along with increased accretion, the lines sometimes also imply high velocity outflows. Given the fact that outbursts can occur as much as 0.15 in phase away from closest approach, we favor accretion over direct magnetospheric interactions as the power source of the outbursts. Away from each other, the stars resemble moderate- to low-activity classical T Tauri stars. There is evidence that some material is stored near the stars and ingested throughout the orbit. These observations are generally consistent with a model for disks in binary systems proposed by Artymowicz & Lubow (1996, ApJ, 467, L77). The importance of this system is that it provides empirical support for continuing accretion through dynamical tidal gaps in disks. It demonstrates that very close binaries can be classical T Tauri systems. (C) 1997 American Astronomical Society.
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页码:781 / 792
页数:12
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