arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2103.09251astro-ph.HEastro-ph.EPastro-ph.SR
收藏

由气盘引起的100质量偏心双星的轨道演化:偏心进旋和圆形出旋

Orbital Evolution of Equal-mass Eccentric Binaries due to a Gas Disk: Eccentric Inspirals and Circular Outspirals

Daniel J. D'Orazio, Paul C. Duffell

摘要:

我们解决二维流体动力学方程描述一个circumbinary盘吸积到偏心,等质量的二。我们计算的时间变化率的二进制半长轴$a$和偏心率$e$在一个连续的范围内的偏心率跨越$e=0$到$e=0.9$。我们发现具有初始偏心率$e_0 \lesssim 0.1$的双星倾向于$e=0$,在那里双星半长轴膨胀。所有其他的都被吸引到$e \approx 0.4$,在那里二元半长轴衰变。$e \approx 0.4$吸引子是由盘响应从近原点对称状态到进动非对称状态的快速变化引起的。状态变化导致时间变化率$\dot{a}$和$\dot{e}$在相同的临界偏心率下急剧改变符号,导致吸引解,其中$\dot{a} = \dot{e} = 0$。然而,这并不会导致一个停滞的、偏心的双星。盘状态之间的有限过渡时间导致的二进制偏心率演变超出吸引偏心率在两个方向上导致振荡的轨道参数和漂移的半长轴。对于所选择的盘参数,具有$e_0 \gtrsim 0.1$的双星朝着$e \approx 0.4$演化,然后围绕其半长轴收缩的位置振荡。由于不等质量的双星通过优先吸积向等质量方向生长,我们的结果适用于很宽的初始双星质量比范围。因此,这些研究结果值得进一步调查这个磁盘过渡;了解其对磁盘参数的依赖性是至关重要的,以确定命运的双星进行轨道演化与一个circumbinary磁盘。

英文摘要:

We solve the equations of two-dimensional hydrodynamics describing a circumbinary disk accreting onto an eccentric, equal-mass binary. We compute the time rate of change of the binary semimajor axis $a$ and eccentricity $e$ over a continuous range of eccentricities spanning $e=0$ to $e=0.9$. We find that binaries with initial eccentricities $e_0 \lesssim 0.1$ tend to $e=0$, where the binary semimajor axis expands. All others are attracted to $e \approx 0.4$, where the binary semimajor axis decays. The $e \approx 0.4$ attractor is caused by a rapid change in the disk response from a nearly origin-symmetric state to a precessing asymmetric state. The state change causes the time rates of change $\dot{a}$ and $\dot{e}$ to steeply change sign at the same critical eccentricity resulting in an attracting solution where $\dot{a} = \dot{e} = 0$. This does not, however, result in a stalled, eccentric binary. The finite-transition time between disk states causes the binary eccentricity to evolve beyond the attracting eccentricity in both directions resulting in oscillating orbital parameters and a drift of the semimajor axis. For the chosen disk parameters, binaries with $e_0 \gtrsim 0.1$ evolve toward and then oscillate around $e \approx 0.4$ where they shrink in semimajor axis. Because unequal mass binaries grow toward equal mass through preferential accretion, our results are applicable to a wide range of initial binary mass ratios. Hence, these findings merit further investigations of this disk transition; understanding its dependence on disk parameters is vital for determining the fate of binaries undergoing orbital evolution with a circumbinary disk.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑