ABSTRACT

The origin of mercury–manganese (HgMn) stars is still poorly understood and the statistical analysis of an extensive sample of well characterized objects would be very valuable. Nevertheless, the compilation of a clean and reliable list of all known HgMn stars, and complete characterization of those objects, is still a pending issue. We report the identification of 13 new HgMn stars from our own spectroscopic observations and from publicly available spectral libraries. In addition, we perform a thorough literature search to give a list of 46 confirmed HgMn stars (plus a further nine suspected HgMn stars) discovered over the last years or neglected by other compilations. When required, we performed specific observations to confirm doubtful cases. For the 13 newly identified HgMn stars we derived photospheric chemical abundances by spectral synthesis. Besides Hg and Mn, which are overabundant in the whole sample, P, Ga, and Xe are overabundant in the hottest stars of the sample, and Sr, Zr, and Pt among the coolest; Y is present in most stars of the sample. Three of these new HgMn stars are members of open clusters: HD 93549 in IC 2602, HD 96473 in NGC 3532, and HD 322659 in NGC 6281. Furthermore, our sample includes HD 145842, an object remarkable for its high rotation. In fact, its projected rotational velocity of v_e sin i = 124 km s⁻¹ is the highest measured in any HgMn star and is more than 30 per cent above the theoretical limit predicted by the diffusion theory, which makes HD 145842 a challenging test case for the current models.

中文翻译：

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发现新的汞锰恒星，包括快速旋转器

摘要

汞-锰（HgMn）星的起源仍然知之甚少，对大量特征明确的物体进行统计分析将非常有价值。尽管如此，如何整理所有已知的HgMn恒星的可靠清单，以及对这些物体的完整表征，仍然是一个悬而未决的问题。我们报告了从我们自己的光谱观测和公共可用的光谱库中鉴定出的13颗新的HgMn恒星。此外，我们进行了全面的文献搜索，以列出在过去几年中发现或被其他汇编所忽略的46颗确认的HgMn恒星（加上另外9颗可疑的HgMn恒星）的列表。必要时，我们进行了具体观察，以确认可疑案件。对于13个新发现的HgMn恒星，我们通过光谱合成得出了光球化学丰度。除了Hg和Mn在整个样品中过量外，P，Ga和Xe在样品中最热的恒星中也过量，而Sr，Zr和Pt则是最冷的。在样品的大多数恒星中都存在Y。这些新的HgMn恒星中的三颗是开放星团的成员：IC 2602中的HD 93549，NGC 3532中的HD 96473和NGC 6281中的HD322659。此外，我们的样本还包括HD 145842，该物体以其高自转着称。实际上，它的预计旋转速度为 IC 2602中的HD 93549，NGC 3532中的HD 96473和NGC 6281中的HD322659。此外，我们的样本还包括HD 145842，该物体以其高旋转性着称。实际上，它的预计旋转速度为 IC 2602中的HD 93549，NGC 3532中的HD 96473和NGC 6281中的HD322659。此外，我们的样本还包括HD 145842，该物体以其高旋转性着称。实际上，它的预计旋转速度为v _e  sin  i = 124 km s ^-1是在任何HgMn恒星中测得的最高值，比扩散理论预测的理论极限高出30％以上，这使HD 145842成为当前模型的具有挑战性的测试案例。