论文标题
非常贫穷的RR Lyre明星，在太阳能街区发现了磁盘轨道
A Very Metal-poor RR Lyrae Star with a Disk Orbit Found in the Solar Neighborhood
论文作者
论文摘要
金属缺陷型恒星是理解星系早期形成的重要示踪剂。最近具有光度和光谱数据的大规模调查报告了金属缺陷型恒星的数量越来越多，其运动学特征与磁盘恒星种群的运动特征一致。我们报告了位于厚磁盘内的Rr〜lyraie变量（以下称为RRL）的发现，其轨道与厚磁化学运动学一致。我们的目标RRL（HD 331986）位于距太阳约1 kpc，v = 11.3是迄今为止已知的130个最亮的RRL之一。但是，该物体几乎没有研究，因为它位于银河系的中间平面，银河纬度约为-1度。它的近红外光谱（0.91-1.32微米）没有吸收线除外，除了帕森系列的氢系，这表明[Fe/H]小于-2.5。它至少是轨道与磁盘运动学一致的RRL中最大的RRL，尽管我们无法确定其所属的磁盘和光环。这种独特的RRL将为我们提供基本的线索，用于研究内星系中恒星的早期形成，并进一步研究，包括高分辨率光谱法。
Metal-deficient stars are important tracers for understanding the early formation of the Galaxy. Recent large-scale surveys with both photometric and spectroscopic data have reported an increasing number of metal-deficient stars whose kinematic features are consistent with those of the disk stellar populations. We report the discovery of an RR~Lyrae variable (hereafter RRL) that is located within the thick disk and has an orbit consistent with the thick-disk kinematics. Our target RRL (HD 331986) is located at around 1 kpc from the Sun and, with V=11.3, is among the 130 brightest RRLs known so far. However, this object was scarcely studied because it is in the midplane of the Galaxy, the Galactic latitude around -1 deg. Its near-infrared spectrum (0.91-1.32 micron) shows no absorption line except hydrogen lines of the Paschen series, suggesting [Fe/H] less than -2.5. It is the most metal-deficient RRL, at least, among the RRLs whose orbits are consistent with the disk kinematics, although we cannot determine to which of the disk and the halo it belongs. This unique RRL would provide us with essential clues for studying the early formation of stars in the inner Galaxy with further investigations, including high-resolution optical spectroscopy.
