The lowest mass white dwarf
The lowest mass white dwarf
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DOI：
10.1086/514327
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发表时间：
2007-05-10
影响因子：
4.9
通讯作者：
Koester, D.
中科院分区：
文献类型：
--
作者：
Kilic, Mukremin;Prieto, Carlos Allende;Koester, D.
极低质量的白矮星是非常罕见的天体，很可能形成于紧凑的双星系统中。我们给出了在超高速B型恒星调查中偶然发现的42个低质量白矮星的MMT光谱。其中一个天体SDSS J0917+46的T-ef=11,288+/-72K，logg=5.48+/-0：03；它的质量估计为0.17M圆点，是目前已知的最低重力/质量白矮星。然而，40颗质量较低的候选恒星是正常的DA白矮星，其SDSS g星等明显不准确。我们重新审视了之前在SDSS中发现的低质量白矮星候选天体的识别，并得出结论：有四个天体有M<；0.2M圆点。这些白矮星都没有显示出来自双星伴星的过量辐射，径向速度搜索将是必要的，以限制看不见的伴星的性质。
Extremely low mass white dwarfs are very rare objects likely formed in compact binary systems. We present MMT optical spectroscopy of 42 low-mass white dwarf candidates serendipitously discovered in a survey for hypervelocity B-type stars. One of these objects, SDSS J0917+46, has T-eff = 11, 288 +/- 72 K and log g = 5.48 +/- 0: 03; with an estimated mass of 0.17 M circle dot , it is the lowest gravity/mass white dwarf currently known. However, 40 of the low-mass candidates are normal DA white dwarfs with apparently inaccurate SDSS g magnitudes. We revisit the identification of low-mass white dwarf candidates previously found in the SDSS and conclude that four objects have M < 0.2 M circle dot. None of these white dwarfs show excess emission from a binary companion, and radial velocity searches will be necessary to constrain the nature of the unseen companions.