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arXiv 1105.4535astro-ph.SR
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由光谱干涉观测确定富C流体静力星的恒星参数

Determination of stellar parameters of C-rich hydrostatic stars from spectro-interferometric observations

C. Paladini, G. T. van Belle, B. Aringer, J. Hron, P. Reegen, C. J. Davis, T. Lebzelter

摘要:

巨星,特别是富碳巨星,对星系的化学富集有重要贡献。确定这些恒星的精确参数是在星系模型中正确实现这一演化阶段的必要先决条件。红外干涉测量为研究巨星的恒星参数开辟了新的视野,并为大气和演化模型提供了新的重要约束条件,本文旨在确定哪些恒星参数可以通过红外干涉测量和光谱学来约束,在C星的情况下,可以达到的精度是多少,限制是什么。为此,我们获得了新的红外光谱,并将它们与未发表的干涉测量五个温和的变化富碳渐近巨星分支星。的意见进行了比较,一个大的网格的流体静力学模型大气和新的等时线,其中包括预测的热脉冲阶段。对于第一次,我们能够再现光谱范围在0.9和4 $μ$ m之间,和$K$宽带干涉与流体静力学模型大气。温度,质量,日志$(g)$,C/O和合理的范围内的距离推导出我们的研究的所有对象。我们所有的目标都至少有一个最佳拟合参数的组合,这些参数位于HR图中预测C星的区域。我们证实,低分辨率光谱是不敏感的质量和log $(g)$测定。对于流体静力学物体,$3\,μ$ m特征对温度变化非常敏感,因此它是精确确定温度的非常有力的工具。干涉测量可以约束质量、半径和log $(g)$,但必须假设距离。富碳恒星距离测量的不确定性仍然是一个主要问题。

英文摘要:

Giant stars, and especially C-rich giants, contribute significantly to the chemical enrichment of galaxies. The determination of precise parameters for these stars is a necessary prerequisite for a proper implementation of this evolutionary phase in the models of galaxies. Infrared interferometry opened new horizons in the study of the stellar parameters of giant stars, and provided new important constraints for the atmospheric and evolutionary models.We aim to determine which stellar parameters can be constrained by using infrared interferometry and spectroscopy, in the case of C-stars what is the precision which can be achieved and what are the limitations. For this purpose we obtained new infrared spectra and combined them with unpublished interferometric measurements for five mildly variable carbon-rich asymptotic giant branch stars. The observations were compared with a large grid of hydrostatic model atmospheres and with new isochrones which include the predictions of the thermally pulsing phase. For the very first time we are able to reproduce spectra in the range between 0.9 and 4 $μ$m, and $K$ broad band interferometry with hydrostatic model atmospheres. Temperature, mass, log$(g)$, C/O and a reasonable range for the distance were derived for all the objects of our study. All our targets have at least one combination of best-fitting parameters which lays in the region of the HR-diagram where C-stars are predicted. We confirm that low resolution spectroscopy is not sensitive to the mass and log$(g)$ determination. For hydrostatic objects the $3\,μ$m feature is very sensitive to temperature variations therefore it is a very powerful tool for accurate temperature determinations. Interferometry can constrain mass, radius and log$(g)$ but a distance has to be assumed. The large uncertainty in the distance measurements available for C-rich stars remains a major problem.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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