论文标题
关于红色超级巨人的肉芽和不规则变化
On Granulation and Irregular Variation of Red Supergiants
论文作者
论文摘要
根据小麦哲伦云（SMC），大麦哲伦云（LMC）和M31的RSG样品，研究了红色超级群（RSG）不规则变化（RSG）的机制和特征。借助来自All Sky自动化调查的超新星（ASAS-SN）和中级Palomar瞬态工厂调查的数据，我们使用连续的时间自动回应移动平均模型来估计光曲线的可变性特征及其功率谱密度。颗粒的特征进化时间尺度和振幅是由将后功率谱密度与COR功能拟合的，这是Harvey样肉芽模型。检查了理论预测和结果的一致性，以验证RSG上颗粒的假设的正确性。获得了肉芽和恒星参数之间的关系，并将其与红色巨型分支恒星和Betelgeuse的结果进行了比较。发现这些关系与肉芽基本物理过程的预测一致，并落在RGB恒星的推断关系中。大多数RSG中的颗粒在几天到一年的时间范围内进化，其特征幅度为10-1000 mmag。结果表明，RSG的不规则变化可以归因于颗粒的演变。在比较SMC，LMC和M31的结果时，颗粒的时间尺度和幅度似乎随着金属性而增加。针对每个星系的RSG样品得出了具有恒星参数的肉芽参数的分析关系。
The mechanism and characteristics of the irregular variations of red supergiants (RSGs) are studied based on the RSG samples in Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC) and M31. With the time-series data from All-Sky Automated Survey for SuperNovae (ASAS-SN) and Intermediate Palomar Transient Factory survey, we use the continuous time autoregressive moving average model to estimate the variability features of the light curves and their power spectral density. The characteristic evolution timescale and amplitude of granulations are further derived from fitting the posterior power spectral density with the COR function, which is a Harvey-like granulation model. The consistency of theoretical predictions and results is checked to verify the correctness of the assumption that granulations on RSGs contribute to irregular variation. The relations between granulation and stellar parameters are obtained and compared with the results of red giant branch stars and Betelgeuse. It is found that the relations are in agreement with predictions from basic physical process of granulation and fall close to the extrapolated relations of RGB stars. The granulations in most of the RSGs evolve at a timescale of several days to a year with the characteristic amplitude of 10-1000 mmag. The results imply that the irregular variations of RSGs can be attributed to the evolution of granulations. When comparing the results from SMC, LMC and M31, the timescale and amplitude of granulation seem to increase with metallicity. The analytical relations of the granulation parameters with stellar parameters are derived for the RSG sample of each galaxy.
