Black Hole Star Destroyer: Scientists Fling Model Stars at a Virtual Black Hole to See Who Survives

Simulations of stars near a supermassive black hole reveal that stellar density plays a bigger role than mass in determining whether stars are torn apart or survive.

In these supercomputer simulations, eight stars are seen avoiding a black hole with a mass one million times that of the Sun. The gravity of the black hole stretches and distorts them all as they get closer. A tidal disruption event, a cataclysmic occurrence that fully separates some into a long stream of gas, occurs in these situations. Others just experience a partial disruption, keeping some of their mass and resuming their original shapes following their terrifying encounters.

Watch eight model stars stretch and deform as they approach a virtual black hole 1 million times the mass of the Sun. The black hole rips some stars apart into a stream of gas, a phenomenon called a tidal disruption event. Others manage to withstand their close encounters. These simulations show that destruction and survival depend on the stars’ initial densities. Yellow represents the greatest densities, blue the least dense. Credit: NASA’s Goddard Space Flight Center/Taeho Ryu (MPA)

These simulations are the first to incorporate the physical implications of Einstein’s general theory of relativity with an accurate stellar density model. They were conducted by Taeho Ryu, a fellow at the Max Planck Institute for Astrophysics in Garching, Germany. The mass of the simulated stars varies from roughly one-tenth to ten times that of the Sun.

There are other factors involved than mass that determine which stars completely disrupt and which ones survive. The density of the star has a greater impact on survival.

Ryu and his team also looked into how differing black hole masses and star close approaches affected tidal disruption events. The findings will assist astronomers in developing more precise models of these catastrophic cosmic catastrophes and in estimating how frequently full tidal disruptions occur in the universe.

Reference: “Tidal Disruptions of Main-sequence Stars. I. Observable Quantities and Their Dependence on Stellar and Black Hole Mass” by Taeho Ryu, Julian Krolik, Tsvi Piran and Scott C. Noble, 25 November 2021, The Astrophysical Journal.
DOI: 10.3847/1538-4357/abb3cf

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