食双星TY CrA再访：近红外光变曲线告诉我们什么
The eclipsing binary TY CrA revisited: What near-IR light curves tell us
摘要：
用VYSOS 6在光学波段和SOFI及REMIR在近红外波段对食分系统TY CrA进行了新的光度观测。这是第一次在近红外波段观测到主序前次级深食极小值，并首次可靠地将次级极小值用于TY CrA的O-C图计算。到目前为止，O-C图可以在大约二十年的时间基础上进行研究。我们确认，O-C图不能解释的光谱三级。首次同时在光学和近红外波段分析了内食双星的光变曲线。结合已经发表的光谱元素，使用ROCHE代码获得初级和次级成分的精确绝对尺寸和质量。近红外数据的包含对由反射星云、光谱第三分量和视觉第四分量组成的第三光提出了强有力的约束。内食双星的绝对参数与以前的工作非常一致，除了主半径（1.46+/-0.15 Rsun）和光度（40+/-10 Lsun）明显较小。虽然当假设年龄约为3-5百万年时，中学的参数是很好理解的，但小学似乎相当小。低金属丰度不能解释原生的参数。
英文摘要：
New photometric observations of the hierarchical eclipsing TY CrA system were taken in the optical with VYSOS6 and in the near-IR with SOFI and REMIR. They are the first observations showing the deep eclipse minimum of the pre-main sequence secondary in the near-IR. For the first time, the secondary minimum can be reliably used in the calculation of the O-C diagram of TY CrA. By now, the O-C diagram can be studied on a time basis of about two decades. We confirm, that the O-C diagram cannot be explained by the spectroscopic tertiary. For the first time, the light curve of the inner eclipsing binary is analysed in both optical and near-IR bands simultaneously. In combination with already published spectroscopic elements, precise absolute dimensions and masses of the primary and the secondary component are obtained using the ROCHE code. The inclusion of the near-IR data puts strong constraints on the third light which is composed of the reflection nebula, the spectroscopic tertiary and a visual fourth component. The absolute parameters of the inner eclipsing binary agree very well with previous work except of the primary radius (1.46+/-0.15 Rsun) and luminosity (40+/-10 Lsun) which are clearly smaller. While the parameters of the secondary are well understood when assuming an age of about 3-5 Myrs, the primary seems considerably undersized. Low metallicity cannot explain the parameters of the primary.
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