arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0908.4133astro-ph.CO
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恒星质量损失的痕迹。I.光学和近红外颜色和表面亮度波动

Tracers of stellar mass-loss. I. Optical and near-IR colours and surface brightness fluctuations

Rosa A. Gonzalez-Lopezlira, Gustavo Bruzual-A., Stephane Charlot, Javier Ballesteros-Paredes, Laurent Loinard

摘要:

我们提出了光学和红外综合颜色和SBF的大小,计算从恒星星族的合成模型,包括从周围的TP-AGB恒星进行质量损失的尘埃信封的排放。我们探讨了由一个数量级的基准值周围的质量损失率的变化的影响,相应地修改恒星参数和输出光谱的TP-AGB恒星加上他们的尘埃信封。这些模型是单次爆发,年龄范围从几百万年到14亿年,金属丰度介于$Z$ = 0.0001和$Z$ = 0.07之间;它们结合了TP-AGB阶段恒星演化的新计算,以及用辐射转移代码DUSTY产生的恒星加包络SED。我们比较这些模型的光学和近红外数据的单个AGB星和麦哲伦星团。这种比较验证了目前的理解的质量损失的作用,在确定恒星参数和光谱的TP-AGB。然而,无论是在光学或近红外波段的宽带颜色或SBF测量可以辨别全球的恒星星族的质量损失率的变化。我们预测中红外SBF测量可以发现这种变化,并实际解决金属丰度和质量损失之间是否存在关系。

英文摘要:

We present optical and IR integrated colours and SBF magnitudes, computed from stellar population synthesis models that include emission from the dusty envelopes surrounding TP-AGB stars undergoing mass-loss. We explore the effects of varying the mass-loss rate by one order of magnitude around the fiducial value, modifying accordingly both the stellar parameters and the output spectra of the TP-AGB stars plus their dusty envelopes. The models are single burst, and range in age from a few Myr to 14 Gyr, and in metallicity between $Z$ = 0.0001 and $Z$ = 0.07; they combine new calculations for the evolution of stars in the TP-AGB phase, with star plus envelope SEDs produced with the radiative transfer code DUSTY. We compare these models to optical and near-IR data of single AGB stars and Magellanic star clusters. This comparison validates the current understanding of the role of mass-loss in determining stellar parameters and spectra in the TP-AGB. However, neither broad-band colours nor SBF measurements in the optical or the near-IR can discern global changes in the mass-loss rate of a stellar population. We predict that mid-IR SBF measurements can pick out such changes, and actually resolve whether a relation between metallicity and mass-loss exists.

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