ARCHEOLOGY OF AN ANCIENT STAR
ARCHEOLOGY OF AN ANCIENT STAR
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DOI：
10.1088/0004-637x/761/2/159
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发表时间：
2012-12
期刊：
影响因子：
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通讯作者：
K. Fuhrmann;R. Chini;M. Haas;M. Hackstein;M. Ramolla;J. Bernkopf
中科院分区：
文献类型：
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作者：
K. Fuhrmann;R. Chini;M. Haas;M. Hackstein;M. Ramolla;J. Bernkopf
本文报道了一颗亮而晚的F型恒星HR3138，从它在[mg/H]-[Fe/mg]丰度平面上的化学组成来看，我们认为它是一个古老的族II成员。然而，进化轨迹与这一发现相矛盾，相反，这意味着HR3138的年龄仅为τ=5.6Gyr 1.8+2.2Gyr(2−)。我们根据现有的高精度径向速度测量来讨论这一争议，这些测量大多排除了蓝散星主星和白矮星副星的情况。虽然人们意识到恒星合并可以主要解决这个问题，而且确实有观测证据表明，由于光球层中没有锂，HR3138上存在质量吸积，但我们也考虑了一个有趣的情况，即HR3138位于距离350PC的年轻疏散星系团NGC2516的方向上。我们指出，这个星系团的前驱星云可能同样可以解释以前的质量吸积，我们特别论证了与这个星云的动力摩擦是场星和疏散星系团惊人共同的银河系自转速度的合理原因。
We report on the bright and late F-type star HR 3138, which, with respect to its chemistry in the [Mg/H]–[Fe/Mg] abundance plane, we identify as an old Population II member. Evolutionary tracks are, however, in conflict with this finding and instead imply an age of only τ = 5.6−1.8+ 2.2 Gyr (2σ) for HR 3138. We discuss this controversy in light of existing high-precision radial velocity surveys that mostly exclude the case of a blue straggler primary and a white dwarf secondary. While it is realized that a stellar merger can principally solve the issue and there is indeed observational evidence for mass accretion on HR 3138 from the absence of lithium in its photosphere, we also consider the interesting circumstance that HR 3138 lies in the direction to the 350 pc distant, young open cluster NGC 2516. We point to the possibility that the progenitor cloud of this cluster may likewise account for former mass accretion and we argue in particular for a dynamical friction with this cloud as a plausible cause for the strikingly common Galactic rotational velocity of the field star and open cluster.