The nature of the 2014–2015 dim state of RW Aurigae revealed by X-ray, optical, and near-IR observations
The nature of the 2014–2015 dim state of RW Aurigae revealed by X-ray, optical, and near-IR observations
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DOI：
10.1051/0004-6361/201527237
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发表时间：
2015-11
影响因子：
6.5
通讯作者：
P. Schneider;H. M. Gunther;J. Robrade;S. Facchini;K. Hodapp;C. Manara;V. Perdelwitz;J. Schmitt;S. Skinner;S. Wolk
中科院分区：
文献类型：
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作者：
P. Schneider;H. M. Gunther;J. Robrade;S. Facchini;K. Hodapp;C. Manara;V. Perdelwitz;J. Schmitt;S. Skinner;S. Wolk
双星系统RW Aur由两颗经典的金牛T星（CTTS）组成。主星系最近经历了第二次观测到的主要变暗事件（V2等）。我们提出了新的，解决钱德拉X射线和UKIRT近红外（NIR）的数据，以及未解决的光学光度学在昏暗的状态下获得研究的气体和尘埃含量的吸收剂引起的调光。X射线数据表明，吸收柱密度从亮态的NH < 0：1 × 10 22 cm 2增加到暗态的2 × 10 22 cm 2。在光学波长到NIR波长下，暗态和亮态之间的亮度比仅显示出中等的波长依赖性，并且NIR颜色-颜色图表明没有实质性的变红。两者合计，这表明灰色吸收的大颗粒（1米）的尘埃质量柱密度为2 × 10 - 4克厘米2。与NH的比较表明，负责光学/NIR调光和X射线吸收的吸收剂与ISM的气尘比兼容，即，晶粒在盘表面层中生长而不会很大程度上改变气尘比。最后，我们讨论了一个方案，其中一个共同的机制可以解释长期的调光RW Aur和最近在AA头。
The binary system RW Aur consists of two classical T Tauri stars (CTTSs). The primary recently underwent its second observed major dimming event ( V 2 mag). We present new, resolved Chandra X-ray and UKIRT near-IR (NIR) data as well as unresolved optical photometry obtained in the dim state to study the gas and dust content of the absorber causing the dimming. The X-ray data show that the absorbing column density increased from NH < 0:1 10 22 cm 2 during the bright state to 2 10 22 cm 2 in the dim state. The brightness ratio between dim and bright state at optical to NIR wavelengths shows only a moderate wavelength dependence and the NIR color‐color diagram suggests no substantial reddening. Taken together, this indicates gray absorption by large grains (&1 m) with a dust mass column density of &2 10 4 g cm 2 . Comparison with NH shows that an absorber responsible for the optical/NIR dimming and the X-ray absorption is compatible with the ISM’s gas-to-dust ratio, i.e., that grains grow in the disk surface layers without largely altering the gas-to-dust ratio. Lastly, we discuss a scenario in which a common mechanism can explain the long-lasting dimming in RW Aur and recently in AA Tau.