Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries
Finding binaries from phase modulation of pulsating stars with Kepler: V. Orbital parameters, with eccentricity and mass-ratio distributions of 341 new binaries
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DOI：
10.1093/mnras/stx3049
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发表时间：
2017-11
影响因子：
4.8
通讯作者：
S. Murphy;M. Moe;D. Kurtz;T. Bedding;H. Shibahashi;H. Boffin
中科院分区：
文献类型：
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作者：
S. Murphy;M. Moe;D. Kurtz;T. Bedding;H. Shibahashi;H. Boffin
中期(102-103d)双星的轨道参数很难用常规方法测量，而且非常不完整。我们进行了一项新的调查，应用我们的脉动计时方法对2224颗主序A/F星的开普勒光曲线进行了测量，发现了341颗非食双星。我们计算了317个PB1系统(单脉冲器双星)和24个PB2系统(双脉冲器)的轨道参数，使具有全轨道解的中等质量双星的数量增加了两倍。该方法达到了小质量比Q≈0.02，并产生了高度均匀的样品。我们用倒置和马尔可夫链蒙特卡罗正演模拟技术对质量比分布进行了参数化，发现它向低质量伴星倾斜，在Q≈0.2时达到峰值。虽然太阳类型的初级恒星在短周期和中期呈现出棕矮星沙漠，但我们发现了一小部分但在统计上有意义的极端质量比伴星(Q0.1，我们测量当前A/F初级恒星的二进制分数为15.4%±1.4%)，尽管我们发现很大一部分伴星(21%±6%)是质量转移后系统中的白矮星，初级恒星现在是蓝散星，其中一些是Ia型超新星、钡星、共生和相关现象的祖先。排除这些白矮星，我们确定在相同的参数空间中，原始A/F主星的二进制分数为13.9%±2.1%。结合我们的测量和文献中的那些，我们发现对于初级恒星M1和lt；0.8M，这些周期的二进制分数是恒定的5%，但随后随着对数M1线性增加，这表明围绕更大质量的原恒星M1 2：1M的新生圆盘变得越来越容易碎裂。最后，我们发现主序列偶的偏心率分布比热分布的偏心率小得多。
The orbital parameters of binaries at intermediate periods (102–103 d) are difficult to measure with conventional methods and are very incomplete. We have undertaken a new survey, applying our pulsation timing method to Kepler light curves of 2224 main-sequence A/F stars and found 341 non-eclipsing binaries. We calculate the orbital parameters for 317 PB1 systems (single-pulsator binaries) and 24 PB2s (double-pulsators), tripling the number of intermediate-mass binaries with full orbital solutions. The method reaches down to small mass ratios q ≈ 0.02 and yields a highly homogeneous sample. We parametrize the mass- ratio distribution using both inversion and Markov-Chain Monte Carlo forward-modelling techniques, and find it to be skewed towards low-mass companions, peaking at q ≈ 0.2. While solar-type primaries exhibit a brown dwarf desert across short and intermediate periods, we find a small but statistically significant (2.6σ ) population of extreme-mass-ratio companions (q 0.1, we measure the binary fraction of current A/F primaries to be 15.4 per cent ± 1.4 per cent, though we find that a large fraction of the companions (21 per cent ± 6 per cent) are white dwarfs in post-mass-transfer systems with primaries that are now blue stragglers, some of which are the progenitors of Type Ia supernovae, barium stars, symbiotics, and related phenomena. Excluding these white dwarfs, we determine the binary fraction of original A/F primaries to be 13.9 per cent ± 2.1 per cent over the same parameter space. Combining our measurements with those in the literature, we find the binary fraction across these periods is a constant 5 per cent for primaries M1 < 0.8 M , but then increases linearly with log M1, demonstrating that natal discs around more massive protostars M1 2: 1M become increasingly more prone to fragmentation. Finally, we find the eccentricity distribution of the main-sequence pairs to be much less eccentric than the thermal distribution.