论文标题
Z = 1/2.5 ZSUN处非常巨大恒星的光谱演变
Spectroscopic evolution of very massive stars at Z = 1/2.5 Zsun
论文作者
论文摘要
在当地宇宙中观察到质量超过100 msun的恒星，但它们仍然是罕见的物体。由于质量功能的形状，预计它们仅存在于最庞大，最年轻的簇中。因此，它们可以在高度恒星的星系中形成数量。非常巨大的恒星（VMS）经历强风，比其质量较低的ob型恒星强。因此，在进化模型和合成光谱中需要考虑这些强风，以正确预测VM的外观。我们介绍了用代码线索计算的进化模型。它们包括最近与VMS相关的质量损失食谱。随后，我们使用代码CMFGEN沿所得轨道计算了大气模型和合成光谱。我们研究了质量在150至400 msun之间的恒星，并专注于金属性Z = 1/2.5ZSUN。我们研究了VMS光谱对年轻Starburst的光谱能量分布的影响。我们表明，与较少的巨星相比，VMS的整个主要序列演变几乎由HEII 4686和HEII 1640发射主导。在紫外光谱范围内，碳，氮和铁线塑造了VMS的光谱，它们的大部分进化都像WNH对象一样。合成光谱的形态与大麦芽云中的VMS相似。我们表明，质量高于100 msun的星星发出的恒星几乎与年轻的Starburst中的所有其他明星一样多。这些星状爆炸的集成紫外线光谱受VMS的存在显着影响。
Stars with masses in excess of 100 Msun are observed in the Local Universe, but they remain rare objects. Because of the shape of the mass function, they are expected to be present only in the most massive and youngest clusters. They may thus be formed in number in highly star-forming galaxies. Very massive stars (VMSs) experience strong stellar winds that are stronger than those of their less massive OB-type counterparts. These strong winds therefore need to be taken into account in evolutionary models and synthetic spectra to properly predict the appearance of VMS. We present evolutionary models computed with the code STAREVOL. They include a recent mass-loss recipe that is relevant for VMSs. We subsequently calculated atmosphere models and synthetic spectra along the resulting tracks with the code CMFGEN. We studied stars with masses between 150 and 400 Msun and focused on a metallicity Z=1/2.5Zsun. We studied the impact of our VMS spectra on the spectral energy distribution of young starbursts. We show that the optical and UV range is dominated by HeII 4686 and HeII 1640 emission for almost the entire main-sequence evolution of VMSs, in contrast to less massive stars. In the UV spectral range, carbon, nitrogen, and iron lines shape the spectra of VMSs, which appear for most of their evolution as WNh objects. The morphology of the synthetic spectra is similar to that of VMSs in the Large Magellanic Cloud. We show that stars with masses higher than 100 Msun emit nearly as much light as all other stars in young starbursts. The integrated UV spectrum of these starbursts is significantly affected by the presence of VMSs.
