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A new study shows that the Milky Way has a grave of dead stars that spans three times the height of the galaxy. Astronomers discovered ancient stellar remains when they first mapped this “galactic underworld”.
our galaxy Formed about 13 billion years agoIt houses billions of stars. Over time, many of these huge objects have crumbled into solid remains.
When a star eight times more massive than the Sun burns its elements and collapses, the star’s outer layer explodes in a supernova. Meanwhile, the star’s core condenses into a neutron star or black hole.
It is easy to detect modern neutron stars and black holes forming in the Milky Way because they stay within our galaxy and conform to their shape. But the ancient stars that resided in the young Milky Way evolved as stellar ghosts when researchers tried to find them.
The supernova explosions that cause stars to collapse actually push them into interstellar space. The researchers determined that 30% of the stellar remains had been ejected from the galaxy entirely, according to their study published in the latest issue of the journal. Royal Astronomical Society Monthly Notices.
The research team was able to determine where stellar remnants persist in and around our galaxy by recreating the life cycles of ancient stars.
“One of the problems with finding these ancient objects is that until now we didn’t know where to look,” said study co-author Peter Tuthill, a professor at the School of Physics and director of the University’s Sydney Institute for Astronomy. from Sidney. In Australia, in a statement.
The oldest neutron stars and black holes appeared when galaxies were younger and different in shape, so they underwent complex changes over billions of years. It was a huge job modeling all of these to find them. It was like trying to find the grave of a legendary elephant. The bones of these rare massive stars must exist, but they seem to darken in the dark. ”
Researchers faced many challenges trying to trace the footsteps and violent death shedding of ancient stars. When a star explodes in a supernova, it gets a “kick”.
The study’s lead author David Sweeney, a medical student at the University of Sydney’s Sydney Astronomy Institute, said in a statement.
Even knowing the size is not enough. The team also had to model the behavior of stars and the orbits they might enter after a supernova experience. Furthermore, there is no friction to slow the speed of the stellar remnants.
“Most of the remnants that formed are still there, crawling like ghosts in interstellar space,” Sweeney said.
The new map includes where the stars in the Milky Way are born, where they explode and where they finally rest.
Comparing the current appearance of the Milky Way with a new model of its stellar explosion reveals a stark difference. The galaxy’s signature spiral arms seem to disappear under all drifting supernova blasts.
The “galactic underworld” also appears to be longer and more prominent than the Milky Way because the supernova’s calcium pushed the remains into a kind of halo formation around the galaxy.
“It was a big surprise,” study co-author Dr Sanjib Sharma, a researcher at the University of Sydney, said in a statement. “Every day I work with images of galaxies that look like we know them today, and I expect the galaxy’s underworld to be very different, but similar in contours. I didn’t expect such a drastic change in shape “.
The research team predicts that the stellar ghost could be hovering relatively close to our sun, from an astronomical point of view.
“Statistically, our closest remnant should be only 65 light-years away – roughly in our backyard, in terms of galaxies,” Tuthill said.
The map will allow scientists to identify individual remains to learn more about the evolution of the galaxy and stellar timelines.
“Now that we know where to look, we are developing techniques to look for,” Sweeney said. “I’m sure the ‘galactic underworld’ won’t be shrouded in mystery any longer.”
