DISCOVERY OF TWO NEW THERMALLY BLOATED LOW-MASS WHITE DWARFS AMONG THE KEPLER BINARIES
DISCOVERY OF TWO NEW THERMALLY BLOATED LOW-MASS WHITE DWARFS AMONG THE KEPLER BINARIES
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DOI：
10.1088/0004-637x/803/2/82
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发表时间：
2015-02
期刊：
影响因子：
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通讯作者：
S. Rappaport;L. Nelson;A. Levine;R. Sanchis-Ojeda;D. Gandolfi;G. Nowak;E. Pallé;A. Prša
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文献类型：
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作者：
S. Rappaport;L. Nelson;A. Levine;R. Sanchis-Ojeda;D. Gandolfi;G. Nowak;E. Pallé;A. Prša
我们在开普勒食双星样本中发现了两颗新的低质量、热膨胀、热白矮星。它们是KIC 9164561和KIC 10727668，轨道周期分别为1.2670天和2.3058天。目前在这两个系统中的主星都是大约2M⊙？>；的A星。这使得开普勒样本中类似双星的数量达到6颗，而这两个新系统的轨道周期是其中最短的。KIC 9164561中的白矮星(WD)的热膨胀比其冷简并半径大约14倍。我们利用KIC 9164561中A星的径向速度测量相当精确地确定了WD质量：0.197±0.005 M⊙？>；KIC 10727668中WD的质量是基于开普勒测光中的多普勒增强信号，不太准确地确定为0.266±0.035 M⊙？根据这两颗白矮星的半径和有效温度，我们可以根据它们失去富氢包层后冷却历史的演化模型，对它们的质量做出独立的理论估计，范围在∼0.01M⊙？>；我们还提出了在KIC 9164561系统中存在第三个天体的证据，其轨道周期为8-14年。
We report the discovery of two new low-mass, thermally bloated, hot white dwarfs among the Kepler sample of eclipsing binaries. These are KIC 9164561 and KIC 10727668 with orbital periods of 1.2670 and 2.3058 days, respectively. The current primary in both systems is an A star of about 2 M ⊙ ?> . This brings the number of similar binaries among the Kepler sample to six, and the two new systems have the shortest orbital periods among them. The white dwarf (WD) in KIC 9164561 has the largest thermal bloating, compared to its cold degenerate radius, of about a factor of 14. We utilize radial velocity measurements of the A star in KIC 9164561 to determine the WD mass rather accurately: 0.197 ± 0.005 M ⊙ ?> . The mass of the WD in KIC 10727668 is based on the Doppler boosting signal in the Kepler photometry and is less accurately determined to be 0.266 ± 0.035 M ⊙ ?> . Based on the inferred radii and effective temperatures of these two white dwarfs, we are able to make an independent theoretical estimate of their masses to within ∼0.01 M ⊙ ?> based on evolutionary models of their cooling history after they lose their hydrogen-rich envelopes. We also present evidence that there is a third body in the KIC 9164561 system with an orbital period of 8–14 yr.