by Scientists have discovered the terrifying secret behind the apparent youth of some of the stars at the heart of the Milky Way – stars taking part in a cosmic demolition derby around our galaxy’s supermassive black hole, Sagittarius A*, or Sgt A* .
Like a cosmic version of 17th-century serial killer Elizabeth Bathory, who apparently sought to maintain her youthful glow by bathing her victims, some of these stars seem to stay looking young through slam put on their neighboring stars and coat themselves in the stolen stellar material. This cannibalistic process leaves the star victim as a strange, stripped “zombie” star, as well as dooms the cannibal star to death soon.
This is just a taste of the strange results of a simulation of 1,000 closely packed stars orbiting the supermassive central black hole of the Milky Way, a study carried out by scientists at Northwestern University.
Related: New view of the supermassive black hole at the heart of the Milky Way hints at a disturbing hidden element (image)
“It is very difficult to observe the centers of other galaxies because they are so far away,” Sanaea C. Rose, a research leader and scientist at Northwestern University, told Space.com. “Studying our own Galactic Center can tell us about what goes on in the centers of all galaxies.”
The heart of the Milky Way is one of the most extreme environments that astronomers can see from Earth. In this region is Sarcel A*, which is not only a black hole with a mass equal to 4.5 million suns, but a cosmic monster orbiting over a million stars.
These stars are crammed into an area about 4 light years wide, about the distance between the sun and its nearest neighbor, Proxima Centauri. This means that events like stellar collisions, which are relatively rare in our region of the Milky Way, involve a small number of people, becoming almost common around Sarcel A*.
“The supermassive black hole at the heart of the Milky Way is surrounded by a very dense cluster of galaxies, many of these stars whizzing around in their orbits at speeds of hundreds to thousands of miles per second,” said Rose.
Studying the violent core of the Milky Way can reveal how stars behave, evolve and interact under the influence of a black hole’s immense gravity.
The part about the demolition Cosmic Derby
While the team’s simulations considered many factors and characteristics, such as stellar mass and star cluster density, one stood out as particularly important when determining the fate of a star near the Milky Way’s core.
Rose explained that, in general, a star’s distance from Sr A* is a good indicator of whether it will collide with another star and what kind of collision it would be.
“The population of the cluster gets bigger and denser the closer you get to the supermassive black hole, so the probability of a collision increases,” she said. ” “It’s a bit like running through an extremely crowded subway station in New York City during rush hour. If you’re not meeting other people, you’re passing them by.”
The closer the star is to Sgr A*, the faster the black hole’s center of gravity hits it. As a result, stars on the supermassive black hole can move at about 18 million miles per hour (29 million kilometers per hour), making the core of the Milky Way more like a demolition derby than a subway. full of New York.
That means collisions in the innermost A* Score region, which refers to an area within about 2,000 times the distance between Earth and the sun, or 0.01 parsecs, are destructive in nature.
Such stars within about 0.01 parsec of Sgr A* constantly collide, but this is rarely a head-on collision. That means, like a demolition derby car that has its bumper ripped off before driving away, the impact of the graze results in a star tearing off its outer layers and then racing on a collision course alongside another neighbor.
“They touch each other and they keep going. They just graze each other because they’re exchanging very violent high-fives,” Rose said.
The amount of material a star loses in this chaos, however, depends on how fast it is moving and how much it overlaps the star it collides with. One result of these destructive collisions is a strange population of stars and young-looking stars that appear young due to the entrapment of hydrogen-rich interstellar material from the former.
However, this youthful appearance comes at a cost. The more massive the star, the faster it burns through the fuel supply it maintains for internal nuclear fusion, a process that prevents it from collapsing under its own gravity. So, by accumulating this stolen matter, these massive stars shorten their own lives.
Farther out from Sgr A*, about 0.1 parsec, or about 21,000 times the distance between the sun and Earth, smaller stars collide more frequently and at slower speeds. When these slower breakups occur, Rose and her colleagues’ simulations showed, a complete merger of two stars into one massive star is likely.
“Collisions outside of 0.01 parsec are more likely to merge colliding stars,” she said. “Stars within 0.1 parsecs of SGR A* have a very high chance of at least one collision during their lifetime.”
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Rose explained that one of the most satisfying aspects of using this model to address some of the unexplained observations of the stars at the heart of the Milky Way is that it is based on a relatively simple calculation.
“Something that I personally found very special about my research is that it is based on calculating the collisional time scale, which is taught quite early in undergraduate physics education,” she said. “It was amazing to use a relatively simple calculation to learn about an incredibly complex environment unlike anything we experience in our solar neighborhood.”
The team has done two studies using the model so far, one published in The Astrophysical Journal Letters this month and another in September 2023, but they are not done with it yet.
“The next steps are to add to the physics that are currently in the model,” Rose said. “The Galactic Center is an incredibly complex environment, so there are always things we can add, and our work is never done!”
Rose presented this research at the April meeting of the American Physical Society, held in Sacramento, California, on Thursday (April 4), as part of the session “Particle Astrophysics and the Galactic Center.”
