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Measurements of Starspot Parameters on Active Stars using Molecular Bands in Echelle Spectra

机译:利用埃歇尔光谱中的分子带测量活性恒星上的星点参数

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We present results from a study of starspot areas (fS) and temperatures (TS), primarily on active, single-lined spectroscopic binaries, determined using molecular absorption bands. Expanding upon our previous studies, we have analyzed multiorder echelle spectra of eight systems to simultaneously measure several different molecular bands and chromospheric emission lines. We determined starspot parameters by fitting the molecular bands of interest, using spectra of inactive G and K stars as proxies for the nonspotted photosphere of the active stars, and using spectra of M stars as proxies for the spots. At least two bands with different Teff sensitivities are required. We found that fitting bands other than the TiO 7055 and 8860 ? features does not greatly extend the temperature range or sensitivity of our technique. The 8860 ? band is particularly important because of its sharply different temperature sensitivity. We did not find any substantial departures from fS or TS that we have measured previously based on single-order spectra. We refined our derived spot parameters using contemporaneous photometry where available. We found that using M giants as spot proxies for subgiant active stars often underestimates fS needed to fit the photometry; this is presumably due to the increase in strength of the TiO bands with decreasing gravity. We also investigated correlations between fS and chromospheric emission, and we developed a simple method to measure nonspot temperature (TQ) solely from our echelle spectra.
机译:我们目前的研究结果来自星点区域(fS)和温度(TS)的研究,主要是利用分子吸收带确定的活跃的单线光谱双星。在我们之前的研究的基础上,我们分析了八个系统的多级阶梯光谱,以同时测量几个不同的分子带和色球层发射线。我们通过拟合感兴趣的分子带,使用非活动的G和K恒星的光谱作为活动恒星的非斑点光球的代理,并使用M恒星的光谱作为光斑的代理,来确定星点参数。至少需要两个具有不同Teff灵敏度的频段。我们发现除了TiO 7055和8860以外,其他的配合带也没有。这些功能不会大大扩展我们技术的温度范围或灵敏度。 8860?由于温度敏感度差异很大,因此该频带特别重要。我们没有发现与之前基于单阶光谱测量的fS或TS有任何实质性差异。我们在可行的情况下使用同期光度法对派生的点参数进行了优化。我们发现,使用M巨星作为次活跃恒星的现货代理经常会低估适合光度法所需的fS;据推测这是由于TiO带的强度随着重力的降低而增加。我们还研究了fS与色球层发射之间的相关性,并且我们开发了一种简单的方法来仅从我们的echelle光谱中测量非斑点温度(TQ)。

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