论文标题
偶然发现的九个白色矮人带有气态碎屑磁盘
Serendipitous Discovery of Nine White Dwarfs With Gaseous Debris Disks
论文作者
论文摘要
基于Gaia DR2数据库选择的白矮星的光谱观测显示，九个新的气态碎片盘绕了单个白色矮人恒星，比以前已知的样品增加了两倍。对于每个来源，我们呈现鉴定的气体发射线和基本的恒星参数，包括低分辨率光谱的线的丰度。原则发现包括：（1）带有气盘的最酷的白矮人（Teff〜12,720 K）；据报道，这颗恒星WD0145+234正在发生最近的红外爆发。 （2）从多个元素的气态发射速度空间中的共同点，表明不同的元素被充分混合； （3）针对SDSSJ0006+2858的高度不对称发射结构，以及其他两个系统的不对称结构； （4）总体样本由大约25％dB和75％的Da白矮人组成，与现场种群中原发性大气类型的总体分布一致； （5）在GAIAJ0611-6931光谱中，从未看到的发射线，Semi Forbidden Mg，CA和Fe线的WD0842+572和Fe线中的Si和Fe线。目前已知的气态碎片盘系统样品显着偏向北半球的恒星，这表明在南半球正在等待十几个发射线星星。
Optical spectroscopic observations of white dwarf stars selected from catalogs based on the Gaia DR2 database reveal nine new gaseous debris disks that orbit single white dwarf stars, about a factor of two increase over the previously known sample. For each source we present gas emission lines identified and basic stellar parameters, including abundances for lines seen with low-resolution spectroscopy. Principle discoveries include: (1) the coolest white dwarf (Teff~12,720 K) with a gas disk; this star, WD0145+234, has been reported to have undergone a recent infrared outburst; (2) co-location in velocity space of gaseous emission from multiple elements, suggesting that different elements are well-mixed; (3) highly asymmetric emission structures toward SDSSJ0006+2858, and possibly asymmetric structures for two other systems; (4) an overall sample composed of approximately 25% DB and 75% DA white dwarfs, consistent with the overall distribution of primary atmospheric types found in the field population; and (5) never-before-seen emission lines from Na in the spectra of GaiaJ0611-6931, semi-forbidden Mg, Ca, and Fe lines toward WD0842+572, and Si in both stars. The currently known sample of gaseous debris disk systems is significantly skewed towards northern hemisphere stars, suggesting a dozen or so emission line stars are waiting to be found in the southern hemisphere.
