发表机构
Zentrum für Astronomie der Universität Heidelberg; Heidelberger Institut für Theoretische Studien（海德堡大学天文中心; 海德堡理论研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究分层恒星包层中动力学摩擦，阐述弱点扰动物体线性正压声响应公式，应用于多种情况，发现分层影响摩擦，双扰动物体系统中伴星尾流有作用，该公式为相关模型提供工具。
AI 中文摘要
用于共包层和行星吞噬吸积的动力学摩擦公式通常假设介质均匀和/或扰动物体直线运动。而嵌入巨星包层中的引力物体在通过有限的径向分层介质的弯曲轨道上运动时会激发轨道尺度的尾流。我们阐述了在静水压、球对称分层气态介质中，弱点扰动物体在圆形轨道上的线性正压声响应。将该公式应用于幂律密度分布和巨星包层模型中的单个扰动物体，以及幂律密度背景下的双扰动物体。发现分层通过尾流的整体结构影响动力学摩擦。径向分量由低阶轨道尺度尾流决定，其幅度和符号与均匀介质结果有很大差异。方位分量也受分层影响，但在超音速状态下保留了均匀问题的库仑对数敏感性。在双扰动物体系统中，伴星尾流可显著改变径向力并减小给定分量上的方位阻力。对于所采用的巨星包层分布，分层尾流施加的方位阻力导致的吸积时间比用相同局部背景量评估的均匀介质公式更短。该公式为计算规定径向分层中嵌入扰动物体的尾流提供了灵活工具，是迈向共包层和行星吞噬吸积计算高效、自洽模型的第一步。
英文摘要
Dynamical friction prescriptions used for common-envelope and planetary engulfment inspirals often assume a homogeneous medium and/or rectilinear perturber motion. A gravitating object embedded in a giant-star envelope instead excites an orbit-scale wake while moving on a curved orbit through a finite, radially stratified medium. We formulate the linear barotropic acoustic response of a weak point perturber on a circular orbit in a hydrostatic, spherically stratified gaseous medium. We apply the formulation to single perturbers in power-law density profiles and giant-star envelope models, and to double perturbers in power-law density backgrounds. We find that stratification affects dynamical friction through the global structure of the wake. The radial component is set by the low-order, orbit-scale wake and can strongly differ in amplitude and sign from the homogeneous-medium result. The azimuthal component is also modified by stratification, but in the supersonic regime it retains the Coulomb-logarithmic sensitivity of the homogeneous problem. In double-perturber systems, the companion wake can substantially change the radial force and reduce the azimuthal drag on a given component, but, unlike the perturber's own wake, it has no local Coulomb-logarithmic contribution. For the adopted giant-star envelope profiles, the azimuthal drag exerted by the stratified wake gives shorter inspiral times than uniform-medium prescriptions evaluated with the same local background quantities. The formulation provides a flexible tool for computing embedded-perturber wakes in prescribed radial stratifications and is a first step toward computationally efficient, self-consistent models of common-envelope and planetary-engulfment inspirals.
Comments21 pages, 19 figures, 1 table. Accepted for publication in A&A
