Black Holes Reanimate Dead Stars Into Stellar Zombies

The cosmos is a mysterious place. Here, black holes can spark life back into dead stars and create a "zombie" for a fleeting moment.

There's a lot people who still don't know about black holes, but it's often seen as great voids that devour the life out of surrounding cosmic objects. It is, to put it simply, a gravitational field so powerful that even light can't escape from its depths.

However, new data shows that black holes are so much more complex than just eating cosmic objects completely.

Black Holes Create 'Zombie Stars'

The study, set for publication in the Astrophysical Journal, reveals that dead sun-like stars called white dwarf stars could experience a brief reanimation in a very specific sequence of events.

When stars or other celestial objects wander too close to a black hole, they typically get simultaneously stretched and compressed in opposite directions by the powerful tidal forces. These stars are eventually torn apart, an event scientists call "tidal disruption events," according to the College of Charleston.

The researchers, led by Chris Fragile of the College of Charleston, found that if the cosmic object is a white dwarf, the compression that occurs in the wake of the black hole encounter may be enough to reignite nuclear fusion in the star for a few seconds.

As Popular Mechanics explains, stars such as the sun don't transform into dense objects when they die. Instead, they blow out the helium and hydrogen layers until only the core of degenerate matter is left. The black hole is able to spark nuclear fusion back into the core for a moment.

However, it's not as simple as just a white dwarf coming across a black hole. Fragile says that two objects must have a close encounter with the star venturing inside what's called the tidal radius. The intermediate black hole should also be the right size between 1,000 to 10,000 times the mass of the sun.

A Rare Event

No zombie stars have ever been witnessed, which isn't surprising considering the extremely specific series of events required for it to happen as well as the brief nature of the phenomenon.

Plus, Fragile points out that intermediate-mass black holes are also incredibly scarce.

"It is important to know how many intermediate mass black holes exist, as this will help answer the question of where supermassive black holes come from," he says in a statement. "Finding intermediate mass black holes through tidal disruption events would be a tremendous advancement."