قيامة أرطغرل الموسم الخامس الحلقة 1: وصول أرطغرل

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قيامة ارطغرل الموسم الخامس الحلقة 1 مسلسلات الريشة

Graveyard of the Suns! Creation of the first ever map of the galactic underworld of dead stars in the Milky Way

The first “galactic underworld” map reveals a graveyard of suns that is 3 times the height of the Milky Way galaxy.

The first map of the ‘galactic underworld’, a map of the once-massive corpses of suns that have since collapsed into black holes and neutron stars, has revealed a graveyard that spans three times the height of the Galaxy of the Milky Way, and that almost a third of the objects were thrown out of the galaxy.

“These compact remnants of dead stars show a fundamentally different distribution and structure from the visible galaxy,” said David Sweeney, PhD student at the Sydney Institute of Astronomy at the University of Sydney and lead author of the paper. in the latest issue of Monthly Notices of the Royal Astronomical Society.

“The ‘height’ of the galactic underworld is more than three times greater in the Milky Way itself,” he added. “And an incredible 30% of the objects were completely ejected from the galaxy.”

Neutron stars and black holes form when massive stars – more than eight times larger than our Sun – run out of fuel and suddenly collapse. This sets off a runaway reaction that blasts the outer parts of the star apart in a titanic supernova explosion, while the core continues to compress until, depending on its starting mass, it becomes either a star at neutrons, or a black hole.

In neutron stars, the core is so dense that electrons and protons are forced to combine at the subatomic level into neutrons, compressing its total mass into a sphere smaller than a city. If the mass of the original star is more than 25 times that of our Sun, this gravity-driven collapse continues until the core is so dense that not even light can escape. Both types of stellar corpses warp the space, time, and matter around them.

Although billions must have formed since the galaxy was young, these alien carcasses were blasted into the darkness of interstellar space by the supernova that created them, and thus escaped the sight and knowledge of astronomers – until now.

By carefully recreating the full life cycle of ancient dead stars, researchers have constructed the first detailed map showing where their corpses lie.

“One of the problems with finding these ancient objects is that, until now, we didn’t know where to look,” said Professor Peter Tuthill of the Institute of Astronomy in Sydney, co-author of the paper. . “The oldest neutron stars and black holes were created when the galaxy was younger and formed differently, then subjected to complex changes spanning billions of years. It has been a major task to model everything to find them.”

Newly formed neutron stars and black holes are consistent with today’s galaxy, so astronomers know where to look. But the oldest neutron stars and black holes are like ghosts still haunting a house demolished long ago, so they’re harder to find.

“It was like trying to find the mythical elephant graveyard,” said Professor Tuthill, referring to a place where, according to legend, old elephants go to die alone, far from their group. “The bones of these rare massive stars must have been there, but they seemed to shroud themselves in mystery.”

Sweeney added: “The most difficult problem I had to solve in tracking down their true cast was accounting for the ‘kicks’ they receive in the violent moments of their creation. Supernova explosions are asymmetrical and the remains are ejected at high speed — up to millions of kilometers per hour — and, even worse, it happens in an unknown and random direction for each object.”

But nothing in the universe stands still for long, so even knowing the likely magnitude of the explosive kicks wasn’t enough: Researchers had to dive into the depths of cosmic time and reconstruct their behavior over billions of years. .

“It’s a bit like snooker,” Sweeney said. “If you know in which direction the ball is hit and with what force, you can determine where it will end up. But in space, objects and speeds are simply much larger. Also, the table is not flat , so the stellar remnants go on complex orbits weaving through the galaxy.

“Finally, unlike a pool table, there’s no friction – so they never slow down. Almost every remnant ever formed is still out there, gliding like ghosts through interstellar space.”

The complex models they built – in collaboration with University of Sydney researcher Dr Sanjib Sharma and Monash University’s Dr Ryosuke Hirai – coded where stars were born, where they met their end fiery and their eventual dispersal as the galaxy evolved.

The end result is a distribution map of the stellar necropolis of the Milky Way.

“It was a bit of a shock,” Dr. Sharma said. “I work every day with images of the visible galaxy as we know it today, and I expected the galactic underworld to be subtly different, but similar in outline. I didn’t expect such a drastic change in shape.”

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