Light and colour variations of Mira variables in the Small Magellanic Cloud
Light and colour variations of Mira variables in the Small Magellanic Cloud
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DOI：
10.1093/mnras/staa3251
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发表时间：
2020-10
影响因子：
4.8
通讯作者：
Y. Ita;J. Menzies;P. Whitelock;N. Matsunaga;M. Takayama;Y. Nakada;T. Tanabé;M. Feast;T. Nagayama
中科院分区：
文献类型：
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作者：
Y. Ita;J. Menzies;P. Whitelock;N. Matsunaga;M. Takayama;Y. Nakada;T. Tanabé;M. Feast;T. Nagayama
本文的目的是描述小麦哲伦云中Mira变星的光变特性。我们研究了一个组合的光学和近红外多历元数据集的Mira变量的基础上，我们的监测数据超过15年。辐射热校正关系制定各种近红外颜色。我们发现，相同的热辐射校正方程适用于两个bolometricly最亮和最暗的脉动阶段。利用时间平均值推导出了周期-测辐射热星等关系和周期-颜色关系。富氧（表面C/O数比小于1）的Mira变星存在辐射热相位与光学和近红外相位的相位滞后，而富碳（表面C/O数比大于1）的Mira变星没有明显的系统滞后。一些Miras显示颜色相位反转，例如，H-Ks在其最蓝处，而J-H和J-Ks在其最红值处，大约在测辐射热最亮的相位处。研究了它们的发生条件，但没有发现明显的直接或间接触发。在具有长次级周期的Miras中观察到与恒星脉动无关的大的近红外颜色变化，并对其可能的解释进行了描述。
The goal of this paper is to characterize the light variation properties of Mira variables in the Small Magellanic Cloud. We have investigated a combined optical and near-infrared multi-epoch data set of Mira variables based on our monitoring data obtained over 15 yr. Bolometric correction relations are formulated for various near-infrared colours. We find that the same bolometric correction equation holds for both the bolometricly brightest and faintest pulsation phases. Period–bolometric magnitude relations and period–colour relations were derived using time-averaged values. Phase lags between bolometric phase and optical and near-infrared phases were detected from the O-rich (the surface C/O number ratio is below unity) Mira variables, while no significant systematic lags were observed in most of the C-rich (the C/O ratio is over unity) ones. Some Miras show colour phase inversions, e.g. H–Ks at its bluest while J–H and J–Ks are at their reddest values at about the bolometricly brightest phase. Their occurrence conditions were studied but no clear direct or indirect trigger was found. A large NIR colour change unassociated with stellar pulsation was observed in Miras with long secondary periods, and its possible explanation is described.