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The most massive white dwarfs in the solar neighbourhood
Monthly Notices of the Royal Astronomical Society ( IF 4.8 ) Pub Date : 2021-03-12 , DOI: 10.1093/mnras/stab767
Mukremin Kilic 1 , P Bergeron 2 , Simon Blouin 3 , A Bédard 2
Affiliation  

We present an analysis of the most massive white dwarf candidates in the Montreal White Dwarf Database 100 pc sample. We identify 25 objects that would be more massive than $1.3\, {\rm M}_{\odot }$ if they had pure H atmospheres and CO cores, including two outliers with unusually high photometric mass estimates near the Chandrasekhar limit. We provide follow-up spectroscopy of these two white dwarfs and show that they are indeed significantly below this limit. We expand our model calculations for CO core white dwarfs up to M = 1.334 M⊙, which corresponds to the high-density limit of our equation-of-state tables, ρ = 109 g cm−3. We find many objects close to this maximum mass of our CO core models. A significant fraction of ultramassive white dwarfs are predicted to form through binary mergers. Merger populations can reveal themselves through their kinematics, magnetism, or rapid rotation rates. We identify four outliers in transverse velocity, four likely magnetic white dwarfs (one of which is also an outlier in transverse velocity), and one with rapid rotation, indicating that at least 8 of the 25 ultramassive white dwarfs in our sample are likely merger products.

中文翻译:

太阳附近最大的白矮星

我们对蒙特利尔白矮星数据库 100 pc 样本中最大的白矮星候选者进行了分析。我们确定了 25 个质量超过 $1.3\, {\rm M}_{\odot }$ 的物体,如果它们具有纯 H 大气和 CO 核心,包括两个异常值,其光度质量估计值在 Chandrasekhar 极限附近异常高。我们提供了这两个白矮星的后续光谱,并表明它们确实明显低于这个限制。我们将 CO 核心白矮星的模型计算扩展到 M = 1.334 M⊙,这对应于我们的状态方程表的高密度极限 ρ = 109 g cm-3。我们发现许多物体接近我们的 CO 核心模型的最大质量。预计很大一部分超大质量白矮星将通过双星合并形成。合并种群可以通过它们的运动学、磁力或快速旋转率来揭示自己。我们确定了四个横向速度异常值、四个可能的磁性白矮星(其中一个也是横向速度异常值)和一个快速旋转,这表明我们样本中的 25 颗超大质量白矮星中至少有 8 颗可能是合并产物.
更新日期:2021-03-12
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