论文标题
通过探测Fe 42多重线在Lamost DR4中搜索壳星
Searching for shell stars in LAMOST DR4 by probing the Fe 42 multiplet lines
论文作者
论文摘要
壳星，尤其是较酷的恒星，通常不会显示出明显的Balmer-line发射，因此在调查中可能会错过，这些调查专门搜索Halpha线中的排放特征。目前的工作旨在通过搜索在档案层光谱中的4924、5018、5169A的强feII多重42行，通过搜索强FEII多重42行来识别恒星。通过使用修改的MKClass代码的修改版本在颜色预先选择的早期恒星样品的光谱中探测FEII 42行的选择，然后通过目视检查其光谱进行分类。我们确定了75颗恒星，显示出明显的壳特征，43 AM/CP1星，12个AP/CP2星和三个具有复合光谱的物体。为壳星的样品提供了FEII 42线的光谱类型和等效宽度测量。除三个物体外，所有壳恒星似乎都从颜色象征图中的ZAM中显着去除，这可能是由于折叠式材料灭绝所致。我们发现5169a线的等效宽度与主要序列恒星轨迹的距离（IR-Excess越大，5169a线越越大）之间的相关性，并使用苔丝数据研究了Shell Star样品的可变性，从而鉴定了非常高的双星。除14个外壳之外，所有的恒星都是新发现，它突出了此处呈现出具有微妙外壳特征的恒星的新方法的效率。这项研究可以用作在大量光谱数据库中发现这些对象的蓝图。
Shell stars, in particular the cooler ones, often do not show conspicuous Balmer-line emission and may consequently be missed in surveys that specifically search for emission signatures in the Halpha line. The present work is aimed at identifying stars with shell-signatures via a search for strong FeII multiplet 42 lines at 4924, 5018, 5169A in archival LAMOST spectra. Candidates were selected by probing the FeII 42 lines in the spectra of a sample of colour-preselected early-type stars using a modified version of the MKCLASS code and then categorised by visual inspection of their spectra. We identified 75 stars showing conspicuous shell features, 43 Am/CP1 stars, 12 Ap/CP2 stars, and three objects with composite spectra. Spectral types and equivalent width measurements of the FeII 42 lines are presented for the sample of shell stars. Except for three objects, all shell stars appear significantly removed from the ZAMS in the colour-magnitude diagram, which is likely due to extinction by circumstellar material. We find a correlation between the equivalent width of the 5169A line and the distance to the locus of the main-sequence stars (the larger the IR-excess, the stronger the 5169A line) and studied the variability of the shell star sample using TESS data, identifying a very high proportion of double stars. All but 14 shell stars are new discoveries, which highlights the efficiency of the here presented novel approach to identify stars with subtle shell features. This study may be used as a blueprint for discovering these objects in massive spectral databases.
