Abstract

Based on moderate-resolution spectra in the range 4200–5200 Å, we have studied B and Be stars in the young open star cluster NGC 581. The temperatures of the program stars have been derived by the differential method with the choice of simple spectroscopic parameters for a number of lines and their comparison with the analogous parameters of a large sample of B stars for which accurate estimates of \(T_{\textrm{eff}}\) were obtained through a non-LTE analysis of their atmospheres. Applying this method to our sample of objects has allowed the cluster age, \(t=22\pm 1\) Myr, and the cluster distance modulus, \((m-M)_{0}=12.4^{m}\), to be determined with confidence. We have studied the spectroscopic variability of the emission spectra for four Be stars in the cluster. All of them are shown to have a long-term variability of the profiles typical of classical Be stars.

中文翻译：

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新生恒星团NGC 581（M 103）中B和Be星的光谱学

摘要

基于4200–5200Å范围内的中等分辨率光谱，我们研究了年轻的开放恒星团NGC 581中的B和Be恒星。程序星的温度是通过微分方法导出的，并选择了简单的光谱参数多条线，并与大量B星样本的类似参数进行比较，通过对它们的大气进行非LTE分析，获得了\（T _ {\ textrm {eff}} \）的准确估计。将这种方法应用于我们的对象样本，可以使聚类年龄\（t = 22 \ pm 1 \） Myr和聚类距离模量\（（mM）_ {0} = 12.4 ^ {m} \），有信心确定。我们研究了星团中四个Be星的发射光谱的光谱变异性。所有这些都显示出经典Be恒星典型的轮廓具有长期变化性。