NASA Simulation Shows What Happens When Stars Get Too Close to Black Holes

What happens to a star when it strays too close to a monster black hole? Astronomers have wondered why some stars are ripped apart, while others manage to survive a close encounter with a lurking black hole, only a little worse for wear.

To figure out the dynamics of such an event, scientists built a supercomputer simulation and tested it out on eight different types of stars. The stars were sent towards a virtual black hole, 1 million times the mass of the Sun.

What they found was surprising.

The stars they modeled ranged in size from about one-tenth to 10 times the Sun’s mass, all with varying densities. All the stars were sent to about 24 million miles away from the black hole at their closest.

The good news is that the Sun-like star survived its close approach (good news for us, anyway). The other stars that survived had 0.15, 0.3, and 0.7 solar masses. But the stars that were 0.4, 0.5, and 3, and 10 times the Sun’s mass were completely torn apart.

Why the disparity?

The researchers realized it wasn’t the star’s size that made the difference for its survival. Instead, the difference between survival and destruction was dependent on the star’s internal density. You can see the details in this video from NASA:

In the simulation above, yellow represents the greatest densities, blue the least dense.

These simulations were led by Taeho Ryu, from the Max Planck Institute for Astrophysics in Garching, Germany. NASA says these simulations are the first to combine the physical effects of Einstein’s general theory of relativity with realistic stellar density models.

The results will help astronomers estimate how often full tidal disruptions occur in the universe and will aid them in building more accurate pictures of these catastrophic events.

You can see all the various simulations here, from NASA’s Scientific Visualization Studio at Goddard Spaceflight Center.

Read the team’s paper, published in the Astrophysical Journal.

Lead image caption: From left to right, this illustration shows four snapshots of a virtual Sun-like star as it approaches a black hole with 1 million times the Sun’s mass. The star stretches, looses some mass, and then begins to regain its shape as it moves away from the black hole. Credit: NASA’s Goddard Space Flight Center/Taeho Ryu (MPA)