Zahn's Theory of Dynamical Tides and Its Application to Stars

TL;DR

This paper critically examines Zahn's dynamical tide theory by comparing its predictions with numerical calculations for stars of 1.5 and 2 solar masses, revealing significantly faster orbital evolution timescales than previously estimated.

Contribution

The study provides a detailed comparison between Zahn's theory and numerical models, highlighting discrepancies and refining understanding of tidal evolution in stars with convective cores and radiative envelopes.

Findings

Zahn's theory overestimates orbital evolution timescales by several orders of magnitude.

Numerical calculations show faster tidal dissipation than predicted by Zahn's model.

Implications for binary star evolution timescales are significant.

Abstract

Zahn's theory of dynamical tides is analyzed critically. We compare the results of this theory with our numerical calculations for stars with a convective core and a radiative envelope and with masses of one and a half and two solar masses. We show that for a binary system consisting of stars of one and a half or two solar masses and a point object with a mass equal to the solar mass and with an orbital period of one day under the assumption of a dense spectrum and moderately rapid dissipation, the evolution time scales of the semimajor axis will be shorter than those in Zahn's theory by several orders of magnitude