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首页> 外文期刊>The Astrophysical journal >Spectropolarimetry and modeling of the eclipsing T Tauri star KH 15D
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Spectropolarimetry and modeling of the eclipsing T Tauri star KH 15D

机译：T Tauri星KH 15D的光谱极光法和建模

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KH 15D is a strongly variable T Tauri star in the young star cluster NGC 2264 that shows a decrease in flux of 3.5 mag lasting for 18 days and repeating every 48 days. The eclipsing material is likely due to orbiting dust or rocky bodies in a partial ring or warped disk that periodically occults the star. We measured the polarized spectrum in and out of eclipse at the Keck and Palomar observatories. Outside of the eclipse, the star exhibited low polarization consistent with zero. During eclipse, the polarization increased dramatically to similar to2% across the optical spectrum, while the spectrum had the same continuum shape as outside of eclipse and exhibited emission lines of much larger equivalent width, as previously seen. From the data, we conclude that ( 1) the scattering region is uneclipsed, ( 2) the scattering is nearly achromatic, and ( 3) the star is likely completely eclipsed so that the flux during eclipse is entirely due to scattered light, a conclusion also argued for by the shape of the ingress and egress. We argue that the scattering is not due to electrons but may be due to large dust grains of size similar to10 mum, similar to the interplanetary grains that scatter the zodiacal light. We construct a warped-disk model with an extended dusty atmosphere that reproduces the main features of the light curve, namely, ( 1) a gradual decrease before ingress due to extinction in the atmosphere ( similar for egress), ( 2) a sharper decrease within ingress due to the optically thick base of the atmosphere, and ( 3) a polarized flux during eclipse that is 0.1% of the total flux outside of eclipse, which requires no fine-tuning of the model. The inclination of the warp is set by the duration of ingress and egress assuming that the warp is located at the Keplerian radius, and the inclination of the observer is then determined by the duration of the eclipse. [References: 29]
机译：KH 15D是年轻恒星团NGC 2264中的T变星T强变星，显示3.5 mag的磁通量减少，持续18天，每48天重复一次。黯淡的物质很可能是由于轨道上的尘埃或岩石体在周期性地掩盖恒星的局部环或弯曲的圆盘中造成的。我们在凯克和帕洛玛天文台测量了食入和食出的偏振光谱。在日食之外，恒星显示出与零一致的低极化。如前所述，在日食期间，偏振在整个光谱范围内急剧增加，接近2％，而光谱具有与日食外部相同的连续谱形状，并显示出更大的等效宽度发射线。根据这些数据，我们得出结论：（1）散射区域没有遮挡，（2）散射几乎是消色差的，并且（3）恒星很可能被完全遮挡了，因此日食期间的通量完全是由散射光引起的，这一结论也由入口和出口的形状主张。我们认为，散射不是由于电子，而是由于大的尘埃颗粒，其大小类似于10微米，类似于散射黄道光的行星际颗粒。我们构建了一个带有扩展的尘埃气氛的翘曲盘模型，该模型再现了光曲线的主要特征，即，（1）由于大气的消光而在进入之前逐渐减小（与出口相似），（2）急剧减小（3）在日食期间的极化通量是日食以外总通量的0.1％，因此不需要对模型进行微调。扭曲的倾斜度由进出的持续时间设定，假设扭曲位于Keplerian半径处，然后观察者的倾斜度由食道的持续时间确定。 [参考：29]

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