“Zombie stars” discovered by American scientists in our galaxy

Some stars orbiting the central supermassive black hole of our Milky Way galaxy look deceptively young.

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But unlike people, who can look rejuvenated after collagen injections, these stars look young for a much darker reason – they “ate” their neighbors. This was established by a new study by scientists from Northwestern University (USA), reports EurekAlert.

As part of the study, astrophysicists simulated the motion of 1 thousand stars orbiting the central supermassive black hole of our galaxy, known as Sagittarius A* (Sgr A*). Densely filled with stars moving at extremely high speeds, this region usually experiences violent collisions between them.

By simulating the consequences of these intense collisions, the new work shows that stars that survive the collision may lose mass and become sparse, low-mass stars, or may merge with other stars, becoming more massive and rejuvenating their appearance, the paper notes.

The center of the Milky Way is a rather strange and stormy place:

• the gravitational pull of Sgr A* accelerates the stars, causing them to circle around their orbits at terrifying speeds of thousands of kilometers per second;
• and the sheer number of stars collected in the center of the galaxy exceeds a million;
• the dense congestion plus lightning speeds are comparable to a high-speed fighter jet race. In the outermost region—within 0.1 parsecs of the black hole—few stars survive unscathed.

It’s akin to a crowded New York City subway station during rush hour. If you do not encounter other people, then you pass by them very close, the scientists note. “For stars, these close encounters still involve their gravitational interaction. We wanted to explore what these collisions and interactions mean for the stellar population and characterize their results.

It is noted that the fate of such stars most likely depends on the distance from the supermassive black hole.

• at a distance of 0.01 parsecs from it, moving stars with speeds reaching thousands of kilometers per second constantly collide with each other. Scientists say this is rarely a head-on collision, more like a violent high-five. Such impacts are not strong enough to completely shatter the stars. Instead, they shed their outer layers and continue to move at high speed along the impact path. These destructive collisions result in a population of strange, impoverished, low-mass stars.
• Beyond 0.01 parsecs, stars move much slower—hundreds of kilometers per second. Due to their lower speed, these stars collide with each other but do not have enough energy to escape. Instead, they merge to become more massive. In some cases, they can even merge several times to become 10 times more massive than our Sun.

Several stars will win the “collision lottery,” scientists note. “Through collisions and mergers, these stars collect more hydrogen. Although they formed from an old population, they masquerade as rejuvenated, young-looking stars. They look like zombie stars; they eat their neighbors.

But stars have to pay for this youth with shorter life expectancies.

They die very quickly, the researchers note. “Massive stars are like giant gas-guzzling cars.” They start with a lot of hydrogen, but they burn it very, very quickly.

Source: EurekAlert

Source: Racurs

David

I am David Wyatt, a professional writer and journalist for Buna Times. I specialize in the world section of news coverage, where I bring to light stories and issues that affect us globally. As a graduate of Journalism, I have always had the passion to spread knowledge through writing.