论文标题
冥王星 - 查隆奏鸣曲四世。对小卫星的动力学行为和质量的改善约束
A Pluto--Charon Sonata IV. Improved Constraints on the Dynamical Behavior and Masses of the Small Satellites
论文作者
论文摘要
我们讨论了一组新的$ \ sim $ 500数值N体计算，旨在限制Styx，Nix，Kerberos和Hydra的质量和散装密度。依靠Lee＆Peale（2006）理论的四个卫星方法的不同技术的不同技术比较，在该理论中，卫星轨道是在受限的三个身体问题的背景下得出的。在每个模拟中，我们都采用肯尼和布罗姆利（Kenyon＆Bromley）（2019a）中的名义卫星质量，将至少一个卫星的质量乘以数值因子$ f \ ge 1 $，并确定该系统是否在时间尺度上弹出至少一个卫星$ \ le 4.5 $ 4.5 $ 4.5 Gyr。当总系统质量大（$ f \ gg 1 $）时，kerberos的弹出更为常见。具有较低卫星质量的系统（$ f \ $ 1）通常会弹出styx。在这些计算中，Styx通常会通过在弹射之前长达较高的轨道倾斜度来“信号”弹射。 Kerberos很少以有用的方式发出信号。 N体的结果表明，Styx和Kerberos的散装密度更可能与水冰相当，$ρ_{SK} \ Lessim $ 2 g cm $^{ - 3} $，而不是与岩石。对总系统质量的强大上限，$ M_ {SNKH} \ Lessim 9.5 \ times 10^{19} $ G，也对四个卫星的平均体积密度进行了强大的约束，$ρ_{SNKH} \ Lessim $ 1.4 g cm $ 1.4 g cm $^{ - 3} $。这些限制支持模型，其中卫星在对冥王星或夏隆的重大影响期间弹出的冰冷材料生长出来。
We discuss a new set of $\sim$ 500 numerical n-body calculations designed to constrain the masses and bulk densities of Styx, Nix, Kerberos, and Hydra. Comparisons of different techniques for deriving the semimajor axis and eccentricity of the four satellites favor methods relying on the theory of Lee & Peale (2006), where satellite orbits are derived in the context of the restricted three body problem (Pluto, Charon, and one massless satellite). In each simulation, we adopt the nominal satellite masses derived in Kenyon & Bromley (2019a), multiply the mass of at least one satellite by a numerical factor $f \ge 1$, and establish whether the system ejects at least one satellite on a time scale $\le$ 4.5 Gyr. When the total system mass is large ($f \gg 1$), ejections of Kerberos are more common. Systems with lower satellite masses ($ f \approx$ 1) usually eject Styx. In these calculations, Styx often `signals' an ejection by moving to higher orbital inclination long before ejection; Kerberos rarely signals in a useful way. The n-body results suggest that Styx and Kerberos are more likely to have bulk densities comparable with water ice, $ρ_{SK} \lesssim$ 2 g cm$^{-3}$, than with rock. A strong upper limit on the total system mass, $M_{SNKH} \lesssim 9.5 \times 10^{19}$ g, also places robust constraints on the average bulk density of the four satellites, $ρ_{SNKH} \lesssim$ 1.4 g cm$^{-3}$. These limits support models where the satellites grow out of icy material ejected during a major impact on Pluto or Charon.
