Bright OB stars in the Galaxy - IV. Stellar and wind parameters of early to late B supergiants
Bright OB stars in the Galaxy - IV. Stellar and wind parameters of early to late B supergiants
复制标题
银河系中明亮的转播星 - IV。
DOI：
10.1051/0004-6361:20077919
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发表时间：
2007
影响因子：
6.5
通讯作者：
J. Puls
中科院分区：
文献类型：
--
作者：
N. Markova;J. Puls
上下文。b型超巨星代表了大质量恒星演化的一个重要阶段。然而，它们的恒星和风参数的可靠估计很少，特别是在中后期光谱亚型。目标。我们应用NLTE大气代码FASTWIND对B0到B9的一小部分银河系b超巨星样本进行了光谱研究。通过得到的数据并结合其他研究的额外数据集，我们研究了ob超巨星的特性，并将我们的发现与理论预测进行了比较。方法。我们的样品恒星的恒星和风参数是通过线形拟合确定的，基于合成剖面，傅里叶技术来研究恒星旋转和“宏观湍流”的个体贡献，以及与微湍流速度并行确定Si丰度的适当方法。结果。由于线覆盖和风覆盖的综合影响，银河系b超巨星的温标需要向下修正，下调10%到20%，后者的值适用于更强的风。与理论预测相比，ob -超巨星的风特性显示出许多差异。与最近的结果相当一致，我们的样本表明在双稳定区域上v∞逐渐减小，该区域的极限位于低于预测的Teff。介绍�
Context. B-type supergiants represent an important phase in the evolution of massive stars. Reliable estimates of their stellar and wind parameters, however, are scarce, especially at mid and late spectral subtypes. Aims. We apply the NLTE atmosphere code FASTWIND to perform a spectroscopic study of a small sample of Galactic B-supergiants from B0 to B9. By means of the resulting data and incorporating additional datasets from alternative studies, we investigate the properties of OB-supergiants and compare our findings with theoretical predictions. Methods. Stellar and wind parameters of our sample stars are determined by line profile fitting, based on synthetic profiles, a Fourier technique to investigate the individual contributions of stellar rotation and “macro-turbulence” and an adequate approach to determine the Si abundances in parallel with micro-turbulent velocities. Results. Due to the combined effects of line- and wind-blanketing, the temperature scale of Galactic B-supergiants needs to be revised downward, by 10 to 20%, the latter value being appropriate for stronger winds. Compared to theoretical predictions, the wind properties of OB-supergiants indicate a number of discrepancies. In fair accordance with recent results, our sample indicates a gradual decrease in v∞ over the bi-stability region, where the limits of this region are located at lower Teff than those predicted. Introducing �