Long-term photometric behaviour of the RS CVn binary RT Lacertae
Long-term photometric behaviour of the RS CVn binary RT Lacertae
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DOI：
10.1051/0004-6361:20030650
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发表时间：
2003-07
影响因子：
6.5
通讯作者：
Ö. Çakırlı;C. Ibanoğlu;G. Djurašević;S. Erkapić;S. Evren;G. Tas
中科院分区：
文献类型：
--
作者：
Ö. Çakırlı;C. Ibanoğlu;G. Djurašević;S. Erkapić;S. Evren;G. Tas
RT Lac的季节性光变曲线的序列，涵盖了1978年至2000年期间，分析的框架内的星点假设，以确定斑点的分布，根据解释的B波段观测。相应的光变曲线的分析是使用Djuray sevic的反问题方法。为了解释光变曲线的变化，我们使用罗氏模型对二元系统进行了建模，该模型涉及两个组件上都包含斑点的区域。假设两个组件上都有斑点，则获得了令人满意的拟合。质量更大的G5主星似乎是系统中最活跃的星星，它的斑点区域是光变曲线扭曲的主要原因。斑点集中在45度-170度的赤道附近和高纬度（45度以上）。我们的分析表明，两个斑点的直径为100毫米-50毫米的两个半球的初级。然而，质量较小的冷组分似乎只有一个点，覆盖面积相对较小。质量较大的主分量的斑点总面积表明，一个周期为8.4年的短期活动周期和一个周期为33.5年的长期活动周期的明显证据。G9 IV次级星系没有显示出任何活动周期的证据，它的光点覆盖范围似乎相当恒定，约占其表面的10%。轨道周期的变化似乎与系统的总活动水平有关。特别是，轨道周期的递减似乎是与最小的斑点和相当大的变化，在每个星星的表面上的表面斑点图案分布。这一结果，如果被未来的观测所证实，可以为最近提出的磁活动和轨道周期变化之间的联系模型提供进一步的支持。
A sequence of the seasonal light curves of RT Lac, covering the period 1978-2000, is analysed in the framework of the starspot hypothesis to define the spot distribution, based on the interpretation of the B-band observations. The analysis of the corresponding light curves is made using Djuray sevic's inverse-problem method. To explain the light-curve variations we modelled the binary system using a Roche model that involved regions containing spots on both components. Satisfactory fits were obtained assuming spots on both components. The more-massive G5 primary appears to be the most active star in the system and its spotted areas are mainly responsible for the light-curve distortions. Spots are concentrated around longitudes 45 ◦ -170 ◦ and at high latitudes (above 45 ◦ ). Our analysis indicates two spots with diameters of ∼10 ◦ -50 ◦ on both hemispheres of the primary. However, the less-massive cool component seems to have only one spot which covers a relatively small area. Total spotted area of the more-massive primary component indicates clear evidence for a short-term activity cycle with a period of 8.4 yr, and a possible long-term cycle with a period of 33.5 yr. The G9IV secondary does not show any evidence for an activity cycle, its spot coverage appearing rather constant at about 10% of its surface. The variation of the orbital period seems to be correlated with the total activity level of the system. In particular, the decrement of the orbital period appears to be associated with minimum spottedness and sizeable changes of the surface spot pattern distribution on the surface of each star. This result, if confirmed by the future observations, can provide further support for recently proposed models for connection between the magnetic activity and orbital period variations.