Two planets orbiting the recently formed post-common envelope binary NN Serpentis
Two planets orbiting the recently formed post-common envelope binary NN Serpentis
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DOI：
10.1051/0004-6361/201015472
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发表时间：
2010-10
影响因子：
6.5
通讯作者：
K. Beuermann;F. Hessman;S. Dreizler;T. Marsh;S. Parsons;D. Winget;G. Miller;M. Schreiber;W. Kley;V. Dhillon;S. Littlefair;C. Copperwheat;J. Hermes
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作者：
K. Beuermann;F. Hessman;S. Dreizler;T. Marsh;S. Parsons;D. Winget;G. Miller;M. Schreiber;W. Kley;V. Dhillon;S. Littlefair;C. Copperwheat;J. Hermes
围绕共同包络后双星运行的行星提供了行星形成和演化的基本信息。我们在NN Ser ab中寻找这样的行星，NN Ser ab是一个日食短周期双星，显示了长期的日食时间变化。使用出版的，重新分析，和新的中期日食时间的NN Ser AB之间获得1988年和2010年，我们发现极好的协议与光旅行时间的影响所产生的两个额外的机构叠加在线性星历的二进制。我们的多参数拟合伴随N体模拟产生锁定在2：1平均运动共振中的对象NN Ser（ab）c和d的最佳拟合，轨道周期P-c类似于或等于15.5年，P-d类似于或等于7.7年，质量M-c sin i（c）类似于或等于6.9 M-Jup，M-d sin i（d）类似于或等于2.2 M-Jup，偏心率e（c）类似于或等于0，e（d）类似于或等于0.20。第二个chi（2）最小值对应于周期比为5：2的另一个解。我们估计，祖先双星由一个A星星与类似或等于2 M-圆点和目前的M矮二次在一个类似的轨道间距为1.5 Au。两颗行星在共同包层阶段的生存创造了现在的白色矮星，这需要在引力和它们在膨胀包层中所经历的拖曳力之间进行微调。另一种选择是在这一阶段结束时创建的环双星盘中的第二代起源。在这种情况下，行星将非常年轻，年龄不超过白色矮星的冷却年龄10（6）岁。
Planets orbiting post-common envelope binaries provide fundamental information on planet formation and evolution. We searched for such planets in NN Ser ab, an eclipsing short-period binary that shows long-term eclipse time variations. Using published, reanalysed, and new mid-eclipse times of NN Ser ab obtained between 1988 and 2010, we find excellent agreement with the light-travel-time effect produced by two additional bodies superposed on the linear ephemeris of the binary. Our multi-parameter fits accompanied by N-body simulations yield a best fit for the objects NN Ser (ab)c and d locked in the 2:1 mean motion resonance, with orbital periods P-c similar or equal to 15.5 yrs and P-d similar or equal to 7.7 yrs, masses M-c sin i(c) similar or equal to 6.9 M-Jup and M-d sin i(d) similar or equal to 2.2 M-Jup, and eccentricities e(c) similar or equal to 0 and e(d) similar or equal to 0.20. A secondary chi(2) minimum corresponds to an alternative solution with a period ratio of 5:2. We estimate that the progenitor binary consisted of an A star with similar or equal to 2 M-circle dot and the present M dwarf secondary at an orbital separation of similar to 1.5 AU. The survival of two planets through the common-envelope phase that created the present white dwarf requires fine tuning between the gravitational force and the drag force experienced by them in the expanding envelope. The alternative is a second-generation origin in a circumbinary disk created at the end of this phase. In that case, the planets would be extremely young with ages not exceeding the cooling age of the white dwarf of 10(6) yrs.