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The Daily Wildcat

The Daily Wildcat


UA study finds black holes may kill stars

A UA professor’s co-authored study found evidence that black holes are ripping apart and killing stars.

On the rare event that a star gets too close to a black hole, gravity will pull the star unevenly on one of its sides. The stretching will continue until the star tears apart and shatters, said Dennis Zaritsky, a professor of astronomy in the Steward Observatory who co-authored the study. The study was published in the Astrophysical Journal.

After analyzing data from the Sloan Digital Sky Survey, a project that took images of the sky, a handful of objects were found that resembled stars being partially swallowed by a black hole. The process of a star being shredded and falling into a black hole is called a tidal disruption event, Zaritsky said.

Most of a star’s matter spirals into the black hole where nothing, not even light, can escape. The remaining material was examined by a team of researchers.

Black holes are located near the center of the galaxy, which is where the star remains were found. Their location is strong evidence that these were indeed tidal disruption events, and not one of the many possibilities that resemble them, Zaritsky said.

After more analysis of the Sloan Digital Sky Survey’s data of a few million galaxies, they settled on two tidal disruption events.

“Could there be some other kind of exploding star that we’ve never seen? Perhaps, but it would have to always happen at the center of galaxies,” Zaritsky said. “Then again, the universe is usually weirder than you think.”

People have been looking for tidal disruption events for at least the last decade, Zaritsky said.

“It’s hard to say this is the first time they’ve been discovered, because other people have put out claims of finding them,” he said. “But this is the first large optical survey where you look for variability and find them that way.”

What if a human fell into a black hole?

“That’s a standard problem we give in class to figure out how stretched you get,” he said. “If you didn’t rip apart initially, you’d get stretched hundreds of feet until you did.”

Under Arizona Stadium, a telescope’s mirror is being finished that will revolutionize the way this type of research is done, Zaritsky said.

The Large Synoptic Survey Telescope’s 8-meter mirror will take images of the entire sky every few nights. The Sloan Digital Sky Survey used a 2-meter mirror telescope.

Zaritsky said the LSST might be ready by 2020.

“We’ll see a lot more tidal disruption events,” Zaritsky said. “We’ll find all sorts of weird things, I guarantee it.”

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