The evolution of red supergiants to supernova in NGC 2100
The evolution of red supergiants to supernova in NGC 2100
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DOI：
10.1093/mnras/stw2054
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发表时间：
2016-08
影响因子：
4.8
通讯作者：
Emma R. Beasor;B. Davies
中科院分区：
文献类型：
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作者：
Emma R. Beasor;B. Davies
红超巨星（RSG）的质量损失率决定了它们向超新星的演化，并决定了由此产生的爆炸的外观。为了研究质量损失率如何随演化而变化，我们测量了大麦哲伦星云中年轻大质量星系团NGC 2100中19颗红超巨星的质量损失率（\mdot）和折射率。通过瞄准同时代星团中的恒星，我们可以在保持质量和金属丰度变量不变的情况下研究质量损失率的演化。质量损失率通过将DUSTY模型拟合到WISE和Spitzer/IRAC的中红外光度测定法来确定。我们发现红超巨星中的mdot随星星的演化而增大，并且被广泛应用于恒星演化计算的de Jager的mdot公式很好地描述。我们发现由温暖的尘埃引起的灭绝是可以忽略不计的，这意味着内部风的温暖的星周物质不能解释与其他星团恒星相比在RSG中发现的更高水平的灭绝。我们讨论了这项工作的超新星祖先和恒星演化理论的影响。我们认为，在RSG阶段大幅增加“mdot”几乎没有理由，因为最近已经提出，以解释没有高质量的IIP型超新星祖先。我们还认为，在红变的增加接近年底的RSG阶段，观察到的两个最进化的星团恒星，可能提供一个解决方案的红超巨星问题。
The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova and dictate the appearance of the resulting explosion. To study how mass-loss rates change with evolution we measure the mass-loss rates (\mdot) and extinctions of 19 red supergiants in the young massive cluster NGC2100 in the Large Magellanic Cloud. By targeting stars in a coeval cluster we can study the mass-loss rate evolution whilst keeping the variables of mass and metallicity fixed. Mass-loss rates were determined by fitting DUSTY models to mid-IR photometry from WISE and Spitzer/IRAC. We find that the \mdot\ in red supergiants increases as the star evolves, and is well described by \mdot\ prescription of de Jager, used widely in stellar evolution calculations. We find the extinction caused by the warm dust is negligible, meaning the warm circumstellar material of the inner wind cannot explain the higher levels of extinction found in the RSGs compared to other cluster stars. We discuss the implications of this work in terms of supernova progenitors and stellar evolution theory. We argue there is little justification for substantially increasing the \mdot\ during the RSG phase, as has been suggested recently in order to explain the absence of high mass Type IIP supernova progenitors. We also argue that an increase in reddening towards the end of the RSG phase, as observed for the two most evolved cluster stars, may provide a solution to the red supergiant problem.