Towards stellar effective temperatures and diameters at 1 per cent accuracy for future surveys
Towards stellar effective temperatures and diameters at 1 per cent accuracy for future surveys
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DOI：
10.1093/mnras/stu089
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发表时间：
2014-01
影响因子：
4.8
通讯作者：
L. Casagrande;L. Portinari;I. Glass;D. Laney;Silva Aguirre;J. Datson;J. Andersen;B. Nordström;J. Holmberg;C. Flynn;M. Asplund
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文献类型：
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作者：
L. Casagrande;L. Portinari;I. Glass;D. Laney;Silva Aguirre;J. Datson;J. Andersen;B. Nordström;J. Holmberg;C. Flynn;M. Asplund
恒星的表观大小是衡量恒星有效温度、半径和表面引力等基本恒星性质的重要基准。虽然对恒星角直径的干涉测量是测量恒星角直径的最直接方法，但它们仍然局限于相对较近和明亮的恒星，这些恒星在大多数现代光度测量中都是饱和的。这种二分法阻止了我们安全地将经过良好校准的关系扩展到大型光谱和光度测量中的目标暗星。在这里，我们通过介绍SAAO对55颗恒星的近红外JHK观测来缓解这一障碍：其中16颗恒星具有干涉角直径，其余的与2MASS(不饱和)数据集相同，使我们能够将通过红外通量方法得出的有效温度和角直径与干涉尺度联系起来。我们将测试扩展到最近对包括巨星在内的非饱和2MASS恒星和缺乏金属的基准目标HD122563的干涉测量。通过对所涉及的系统学进行严格的评估，我们得出结论，基本恒星参数的1%的精度通常是可以达到的。然而，当通过颜色关系间接测试温度标尺时，以及在评估干涉测量的可靠性时，尤其是在亚毫弧秒级别时，必须谨慎。结果，完全不同的有效温度标度可以与给定的干涉数据子集兼容。我们强调了在这样的探索中需要注意的一些警告，并建议了一种简单的方法来检查基本测量中的系统学。文中还提出了一种新的地震半径与天文距离相结合的诊断方法。
The apparent size of stars is a crucial benchmark for fundamental stellar properties such as effective temperatures, radii and surface gravities. While interferometric measurements of stellar angular diameters are the most direct method to gauge these, they are still limited to relatively nearby and bright stars, which are saturated in most of the modern photometric surveys. This dichotomy prevents us from safely extending well calibrated relations to the faint stars targeted in large spectroscopic and photometric surveys. Here, we alleviate this obstacle by presenting SAAO near-infrared JHK observations of 55 stars: 16 of them have interferometric angular diameters, and the rest are in common with the 2MASS (unsaturated) dataset, allowing us to tie the effective temperatures and angular diameters derived via the Infrared Flux Method to the interferometric scale. We extend the test to recent interferometric measurements of unsaturated 2MASS stars, including giants, and the metal-poor benchmark target HD122563. With a critical evaluation of the systematics involved, we conclude that a 1% accuracy in fundamental stellar parameters is usually within reach. Caution, however, must be used when indirectly testing a temperature scale via colour relations, as well as when assessing the reliability of interferometric measurements, especially at sub-milliarcsec level. As a result, rather different effective temperature scales can be compatible with a given subset of interferometric data. We highlight some caveats to be aware of in such a quest, and suggest a simple method to check against systematics in fundamental measurements. A new diagnostic combination seismic radii with astrometric distances is also presented.