论文标题
$ \ textit {gaia} $ 40 pc中的白色矮人：新候选人的光谱观察
$\textit{Gaia}$ white dwarfs within 40 pc I: spectroscopic observations of new candidates
论文作者
论文摘要
我们对William Herschel望远镜和Gran Telescopio Canarias的太阳40 PC内的230名白矮人候选人进行了光谱调查。从$ \ textit {gaia} $数据版本2（DR2）中选择所有候选人，几乎在所有情况下都没有先前的光谱分类。我们发现共有191个确认的白矮人和39个主要恒星污染物。样品中的大多数恒星残留物相对较酷（$ \ langle t _ {\ rm eff} \ rangle $ = 6200 K），显示了氢级式级式浆料线或无特征光谱，分别对应于89 da和76 dc White dc White Dwarfs。我们还恢复了两个DBA白色矮人和9--10磁性残留物。我们发现了两个含碳的DQ星和14个新的金属富含白色矮人。这包括可能检测到第一个具有金属线的超酷白色矮人。我们描述了三个DZ恒星，我们发现至少四种不同的金属物种，其中一种是强烈的Fe-和Ni富含的金属物种，表明具有核心 - 地球成分的行星的积聚。我们发现一个极其巨大的（1.31 $ \ pm $ 0.01 m $ _ {\ odot} $）da White矮人显示薄弱的Balmer线，可能表明出色的磁性。另一个白色矮人显示出强大的Balmer线排放，但没有红外线过量，这表明是低质量的亚赛车伴侣。现已在40 pc样本中，北半球（$δ> $ 0 deg）中的$ \ textit {gaia} $ dr2来源达到高光谱完整性（$> $ 99％），位于赫尔茨普朗格·鲁塞尔（Hertzsprungung-Russell Russell Russell）图中的白矮人冷却轨道上。同伴论文中介绍了全北部样本的统计研究。
We present a spectroscopic survey of 230 white dwarf candidates within 40 pc of the Sun from the William Herschel Telescope and Gran Telescopio Canarias. All candidates were selected from $\textit{Gaia}$ Data Release 2 (DR2) and in almost all cases had no prior spectroscopic classifications. We find a total of 191 confirmed white dwarfs and 39 main-sequence star contaminants. The majority of stellar remnants in the sample are relatively cool ($\langle T_{\rm eff} \rangle$ = 6200 K), showing either hydrogen Balmer lines or a featureless spectrum, corresponding to 89 DA and 76 DC white dwarfs, respectively. We also recover two DBA white dwarfs and 9--10 magnetic remnants. We find two carbon-bearing DQ stars and 14 new metal-rich white dwarfs. This includes the possible detection of the first ultra-cool white dwarf with metal lines. We describe three DZ stars for which we find at least four different metal species, including one which is strongly Fe- and Ni-rich, indicative of the accretion of a planetesimal with core-Earth composition. We find one extremely massive (1.31 $\pm$ 0.01 M$_{\odot}$) DA white dwarf showing weak Balmer lines, possibly indicating stellar magnetism. Another white dwarf shows strong Balmer line emission but no infrared excess, suggesting a low-mass sub-stellar companion. High spectroscopic completeness ($>$99%) has now been reached for $\textit{Gaia}$ DR2 sources within 40 pc sample, in the northern hemisphere ($δ>$ 0 deg) and located on the white dwarf cooling track in the Hertzsprung-Russell diagram. A statistical study of the full northern sample is presented in a companion paper.
