A Planetesimal Accretion Zone in a Circumbinary Disk
A Planetesimal Accretion Zone in a Circumbinary Disk
复制标题
DOI：
10.1086/421342
复制
发表时间：
2003-11
期刊：
影响因子：
--
通讯作者：
Kazumasa Moriwaki;Y. Nakagawa
中科院分区：
文献类型：
--
作者：
Kazumasa Moriwaki;Y. Nakagawa
本文研究了环双星盘中小行星吸积的条件。直到最近，人们一直认为只有单一的太阳型恒星可能拥有行星系统。另一方面，环双星盘已经被红外线或无线电观测发现。行星可以在这样的盘中形成。双星系统对靠近双星轨道的微行星有更强的引力扰动。因此，微行星之间的相对速度会更大，当它们超过逃逸速度时，微行星就不可能聚集成行星。我们进行了长期的数值积分的二元和星子的轨道运动的框架内的共面椭圆形限制性三体问题，并找到了上限的轨道半径内的星子之间的相对速度超过逃逸速度。结果表明，当双星半长轴为1 Au，双星偏心率为0.1，双星总质量为m1 + m2 = 1 M，质量比为m2/（m1 + m2）= 0.2时，在距双星质心13 Au以内的区域不可能发生星子吸积。在超过13个Au的区域，微行星可以增生。根据长期摄动理论，我们还导出了双星引力摄动所抽升的星子离心率和星子吸积带内边界半径的解析表达式。
We investigate the conditions for planetesimal accretion in a circumbinary disk. Until recently, it had been believed that only single solar-type stars might harbor planetary systems. On the other hand, circumbinary disks have been detected by infrared or radio observation. Planets may be formed in such disks. Binary systems give stronger gravitational perturbation against planetesimals orbiting nearer to the binary. Therefore, the relative velocities between planetesimals will be larger and when they exceed the escape velocity it is impossible for the planetesimals to accumulate into planets. We performed long-term numerical integrations of binary and planetesimal orbital motions in the framework of the coplanar elliptic restricted three-body problem and have found the upper limit of the orbital radius inside of which the relative velocity between the planetesimals exceeds the escape velocity. One of our results is that planetesimal accretion cannot occur in a zone within 13 AU from the barycenter of the binary system when the binary semimajor axis is 1 AU, the binary eccentricity 0.1, the total mass m1 + m2 = 1 M☉, and the mass ratio m2/(m1 + m2) = 0.2. In regions farther out than 13 AU, planetesimals can accrete. We also derive analytic expressions of the eccentricity of a planetesimal pumped up by the gravitational perturbation of the binary and the inner boundary radius of the planetesimal accretion zone according to the secular perturbation theory.