Keck HIRES Spectroscopy of Four Candidate Solar Twins
Keck HIRES Spectroscopy of Four Candidate Solar Twins
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凯克聘请了四个候选太阳双胞胎的光谱学
DOI：
10.1086/452640
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
S. Schuler
中科院分区：
文献类型：
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作者：
J. King;A. Boesgaard;S. Schuler
我们使用高信噪比、高分辨率的Keck HIRES光谱对四个太阳孪生候选天体（HIP 71813、76114、77718和78399）进行了参数和丰度分析，这些天体来自我们基于hipparcos的Ca II H和K调查。我们的光谱Teff估计比最近日内瓦-哥本哈根调查的光度尺度热约100 K；一些证据表明太阳Teff的光度温度太低了。同时，我们在日内瓦-哥本哈根调查中发现的三个太阳双生子候选行星的丰度与光度金属丰度非常吻合；没有迹象表明某些晚g星群和毕宿星的光度金属丰度异常低。首次确定了HIP 78399的径向速度，并推导了所有恒星的UVW运动学。HIP 71813似乎是Wolf 630移动群的一员（在最近对喜巴谷晚期恒星的分析中，这个结构显然被重新确认了），但它的金属丰度比最近对该群金属丰度的估计高0.1个指数。虽然HIP 76114和77718肯定是太阳类型的恒星，但与太阳相比，它们的质量要小百分之几，年龄更大，金属含量也更少；它们既不是很好的太阳双胞胎候选者，也不是太阳的类似物，提供了太阳在其他演化阶段的观察。HIP 71813似乎是一个极好的太阳模拟物，年龄为~ 8 Gyr。我们对HIP 78399的研究结果表明，这颗恒星作为太阳双胞胎的前景可能相当于“最接近的太阳双胞胎”HR 6060；鼓励对这颗恒星进行后续研究。
We use high signal-to-noise ratio, high-resolution Keck HIRES spectroscopy of four solar twin candidates (HIP 71813, 76114, 77718, and 78399) pulled from our Hipparcos-based Ca II H and K survey to carry out parameter and abundance analyses of these objects. Our spectroscopic Teff estimates are ∼100 K hotter than the photometric scale of the recent Geneva-Copenhagen survey; several lines of evidence suggest the photometric temperatures are too cool at solar Teff. At the same time, our abundances for the three solar twin candidates included in the Geneva-Copenhagen survey are in outstanding agreement with the photometric metallicities; there is no sign of the anomalously low photometric metallicities derived for some late-G UMa group and Hyades dwarfs. A first radial velocity determination is made for HIP 78399 and UVW kinematics derived for all stars. HIP 71813 appears to be a kinematic member of the Wolf 630 moving group (a structure apparently reidentified in a recent analysis of late-type Hipparcos stars), but its metallicity is 0.1 dex higher than the most recent estimate of this group's metallicity. While certainly solar-type stars, HIP 76114 and 77718 are a few percent less massive, significantly older, and metal-poor compared to the Sun; they are neither good solar twin candidates nor solar analogs providing a look at the Sun at some other point in its evolution. HIP 71813 appears to be an excellent solar analog of ∼8 Gyr age. Our results for HIP 78399 suggest the promise of this star as a solar twin may be equivalent to the "closest ever solar twin," HR 6060; follow-up study of this star is encouraged.