遥远太阳双胞胎巡天（SDST）- III。新的太阳孪星和太阳类星体的识别
Survey for Distant Solar Twins (SDST) -- III. Identification of new solar twin and solar analogue stars
摘要：
遥远太阳双星巡天（SDST）的目标是寻找与太阳非常相似的恒星，距离为1-4 kpc，比目前已知的任何太阳双星和类似物都要远几倍。我们的目标是找出最好的恒星，以测试我们银河系中的精细结构常数α是否随暗物质密度而变化。在这里，我们使用EPIC，我们的逐线差分技术，测量恒星的参数-有效温度Teff，表面重力log g，金属丰度[Fe/H] -从中等分辨率（R <32，000）光谱的877个太阳孪星和类似候选者（547个在1-4 kpc），由英澳望远镜上的HERMES摄谱仪观测。这些是一致的预期Teff和日志g测光，[Fe/H]从贝桑松恒星星族模型。EPIC提供了足够小的不确定性（~90 K，0.08 dex，0.05 dex，分别），即使在低信噪比（S/N >~ 25每像素），以确定299个新的太阳类似物（> 90%的信心），和20个太阳孪生（>50%的信心），其中206和12个是在1-4千秒差距。通过扩展EPIC来测量来自HERMES光谱的谱线展宽和锂丰度，并使用来自与我们的恒星参数拟合的等时线的年龄，我们确定了174个在1-4 kpc的太阳类似物，它们相对不活跃，旋转缓慢，并且没有光谱双星的证据。这些是后续光谱测量α的首选目标。
英文摘要：
The Survey for Distant Solar Twins (SDST) aims to find stars very similar to the Sun at distances 1-4 kpc, several times more distant than any currently known solar twins and analogues. The goal is to identify the best stars with which to test whether the fine-structure constant, alpha, varies with dark matter density in our Galaxy. Here we use EPIC, our line-by-line differential technique, to measure the stellar parameters - effective temperature Teff, surface gravity log g, metallicity [Fe/H] - from moderate resolution (R < 32,000) spectra of 877 solar twin and analogue candidates (547 at 1-4 kpc) observed with the HERMES spectrograph on the Anglo-Australian Telescope. These are consistent with expectations for Teff and log g from photometry, and for [Fe/H] from the Besancon stellar population model. EPIC provides small enough uncertainties (~90 K, 0.08 dex, 0.05 dex, respectively), even at the low signal-to-noise ratios available (S/N >~ 25 per pixel), to identify 299 new solar analogues (> 90% confidence), and 20 solar twins (>50% confidence), 206 and 12 of which are at 1-4 kpc. By extending EPIC to measure line broadening and lithium abundance from HERMES spectra, and with ages derived from isochrone fitting with our stellar parameters, we identify 174 solar analogues at 1-4 kpc which are relatively inactive, slowly rotating, and with no evidence of spectroscopic binarity. These are the preferred targets for follow-up spectroscopy to measure alpha.
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