Stars Crushed by Black Holes. III. Mild Compression of Radiative Stars by Supermassive Black Holes

Suman Kumar Kundu, Eric R. Coughlin, C. J. Nixon

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


A tidal disruption event (TDE) occurs when the gravitational field of a supermassive black hole (SMBH) destroys a star. For TDEs in which the star enters deep within the tidal radius, such that the ratio of the tidal radius to the pericenter distance β satisfies β ≫ 1, the star is tidally compressed and heated. It was predicted that the maximum density and temperature attained during deep TDEs scale as ∝ β 3 and ∝ β 2, respectively, and nuclear detonation is triggered by β ≳ 5, but these predictions have been debated over the last four decades. We perform Newtonian smoothed-particle hydrodynamics simulations of deep TDEs between a Sun-like star and a 106 M SMBH for 2 ≤ β ≤ 10. We find that neither the maximum density nor temperature follow the ∝ β 3 and ∝ β 2 scalings or, for that matter, any power-law dependence, and that the maximum-achieved density and temperature are reduced by ∼1 order of magnitude compared to past predictions. We also perform simulations in the Schwarzschild metric and find that relativistic effects modestly increase the maximum density (by a factor of ≲1.5) and induce a time lag relative to the Newtonian simulations, which is induced by time dilation. We also confirm that the time the star spends at high density and temperature is a very small fraction of its dynamical time. We therefore predict that the amount of nuclear burning achieved by radiative stars during deep TDEs is minimal.

Original languageEnglish (US)
Article number71
JournalAstrophysical Journal
Issue number2
StatePublished - Nov 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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