In beyond-Horndeski theories of gravity, the Vainshtein screening mechanism might only be partially effective inside stellar objects. This results in a modification of the pressure balance equation inside stars, often characterized by a single parameter ($Υ$) in isotropic systems. We show how to constrain such theories of modified gravity, using tidal effects. We study such effects in cataclysmic variable star binaries and numerically obtain limits on the critical masses of the donor stars, below which they are tidally disrupted, by modeling them in beyond-Horndeski theories. This is contrasted with values of the donor masses, obtained using existing observational data, by a Monte Carlo error progression method. A best fit scenario of the two yields a parametric constraint in the theories that we consider, within the approximations used. Here, we obtain the allowed range $ 0 \le Υ\le 0.47 $.
Evolution of binary objects under the influence of tides drastically affects the expected observational properties of the system. With the discovery of a large number of close-in hot Jupiter systems and eclipsing binaries from missions such as Kepler and TESS, it has become imperative to understand the extent of tidal influence on their formation and observed properties. In the case of binary systems, an efficient tidal dissipation can lead to either spin up or spin down of the stars and/or spin-orbit synchronization, depending upon the exchange of angular momentum between the star and the orb…
Constraining Tidal Migration with the Hot Jupiter Population
Princeton University（普林斯顿大学）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；Canadian Institute for Theoretical Astrophysics（加拿大理论天体物理研究所）；University of California Los Angeles（加州大学洛杉矶分校）
We extend the quark mean-field (QMF) model for nuclear matter and study the possible presence of quark matter inside the cores of neutron stars. A sharp first-order hadron-quark phase transition is implemented combining the QMF for the hadronic phase with "constant-speed-of-sound" parametrization for the high-density quark phase. The interplay of the nuclear symmetry energy slope parameter, $L$, and the dimensionless phase transition parameters (the transition density $n_{\rm trans}/n_0$, the transition strength $Δ\varepsilon/\varepsilon_{\rm trans}$, and the sound speed squared in quark matte…
We revisit the Tidally Excited Oscillations (TEOs) in the A-type, main-sequence, eccentric binary KOI-54, the prototype of heartbeat stars. Although the linear tidal response of the star is a series of orbital-harmonic frequencies which are not stellar eigenfrequencies, we show that the non-linearly excited non-orbital-harmonic TEOs are eigenmodes. By carefully choosing the modes which satisfy the mode-coupling selection rules, a period spacing ($ΔP$) pattern of quadrupole gravity modes ($ΔP \approx 2520-2535$ sec) can be discerned in the Fourier spectrum, with a detection significance level o…
A new class of pulsating binary stars was recently discovered, whose pulsation amplitudes are strongly modulated with orbital phase. Stars in close binaries are tidally distorted, so we examine how a star's tidally induced asphericity affects its oscillation mode frequencies and eigenfunctions. We explain the pulsation amplitude modulation via tidal mode coupling such that the pulsations are effectively confined to certain regions of the star, e.g., the tidal pole or the tidal equator. In addition to a rigorous mathematical formalism to compute this coupling, we provide a more intuitive semi-a…
According to core-accretion formation models, the conditions under which gas giants will form around M dwarfs are very restrictive. Also, the correlation of the occurrence of these planets with the metallicity of host stars is still unknown due to the intrinsic faintness of M dwarfs in the optical and some intricacies in their spectra. Interestingly, NASA's TESS mission has started to create a growing sample of these systems, with eleven observed planets located in close-in orbits: contrary to what is expected for low stellar masses. Tidal interactions with the host star will play a key role i…
Effect of the stellar spin history on the tidal evolution of close-in planets
我们研究如何恒星的自旋速率的演变影响，并受到影响，在近轨道的行星，通过恒星行星潮汐相互作用。为此，我们使用标准的平衡潮汐模型来计算围绕类太阳恒星和0.1 M \odot M矮星运行的单个行星的轨道演化。我们测试了两个恒星的自旋演化曲线，一个是快速的初始旋转（P=1.2天），一个是缓慢的初始旋转（P=8天）。我们测试了改变恒星和行星耗散以及行星质量和初始轨道半径的影响。结论：潮汐演化允许区分早期行为的非常接近行星轨道无论是快速旋转的恒星或缓慢旋转的恒星。恒星的早期自旋使快速旋转体周围的近距离行星能够在早期演化中幸存下来。对于M矮星周围的行星来说，在早期演化中幸存下来意味着在Gyr时间尺度上幸存下来，而对于类太阳恒星来说，自旋下降带来了木星行星的后期合并。根据这项研究，我们可以说，在给定行星当前位置的情况下，区分一种自旋演化与另一种自旋演化是非常棘手的。除非我们能观察到以前演化的某些标志，否则几乎不可能区分这两种截然不同的自旋分布，更不用说中间自旋分布了。尽管如此，仍然可以从完全对流的M矮星周围行星的统计分布中得出一些结论。然而，如果潮汐演化在其历史的后期带来了合并，它也可能导致恒星在晚期的明显加速，因此有可能有快速旋转的老恒星。这就提出了更好地限制恒星年龄的问题。
Context. With the detection of thousands of exoplanets, characterising their dynamical evolution in detail represents a key step in the understanding of their formation. Studying the dissipation of tides occurring both in the host star and in the planets is of great relevance in order to investigate the distribution of the angular momentum occurring among the objects populating the system and to studying the evolution of the orbital parameters. From a theoretical point of view, the dissipation of tides throughout a body may be studied by relying on the so-called phase or time-lag equilibrium t…
