Massive stars usually die in spectacular explosions, while a handful of stars fade like unexploded firecrackers.
Astronomers have identified the remains of one such unexploded firecracker on SGR 0755-2933. neutron star about 11,400 light years from earth Pupis, the southern constellation. In a new study, scientists believe that this early in life star Transferred an unusually large amount of mass to the binary companion — so there wasn’t enough material left to explode to death.Instead, it ended with a silent ‘ultra-strip’ supernovaa rare cosmic event that leaves behind an ultra-dense remnant called a neutron star.
“This amazing binary system is essentially a 1 in 10 billion system,” says André-Nicolas Chené, an astronomer at the National Science Foundation’s NOIRLab research center and co-author of the new study. says so. statement.
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A neutron star and its orbiting binary companion, a star that researchers also predict will one day collapse into a neutron star, represents the first clear example of a star system that would eventually cause a massive explosion. I’m here. Kironovathe cosmic explosion in which two neutron stars merge.
Even though it was a kilonova First detected in 2017astronomers recorded only the aftermath of the event, thanks to observations of light and gravitational waves.
What’s more, astronomers have traditionally thought that only one or two such systems exist in spiral galaxies like ours. milky wayThe researchers in the latest study have now increased that estimate to 10, and say that these observations will help us better understand the history, evolution and unusual deaths of stars in such systems. I’m paying attention.
“For quite some time, astronomers have speculated about the exact conditions that could eventually lead to Kilonova,” Shené said in a statement. “These new results show that, at least in some cases, he of two sibling neutron stars can merge if one is created without a classical supernova explosion.”
This sibling star is massive, orbits a primary neutron star every 60 days, and has a name that looks like a license plate: CPD-29 2176. as a possible future development.
“This is not a simple binary system”
Clarissa Pavao, an undergraduate at Embry-Riddle Aeronautical University in Arizona, discovered the system while poring over data acquired by Chile’s Cerro Tololo InterAmerican Observatory.especially she spectrum Analysis of how much light a star emits at a particular wavelength, of its sibling stars. After removing noise from the data, she noticed one simple line in her spectrum suggesting that massive stars have highly circular orbits. This is a rare feature in binary star systems.
This was a key discovery that helped the team conclude that the primary neutron star ended up as a dud supernova, the astronomers said.
Normally, when one of the stars in a binary system burns up hydrogen and nears its end, Main train In stages, it begins to transfer mass to the companion star. The resulting end-of-life explosion often drives the companion star out of the system and into a highly elliptical orbit.
However, this doesn’t seem to happen on the intriguing system. To better understand what happened at the end of SGR 0755-2933’s lifetime, astronomers looked at thousands of models describing binary systems similar to the one they were studying. . Only two matches were found.
The team then traced the star’s history and concluded that, for the most part, it behaved like any other massive star that ran out of fuel. Towards the end of its life, the star began to transfer mass to its peers and was reduced to a low-mass star. It has a helium core, just as scientists expected. However, the star lost so much mass in the process that the end-of-life supernova “didn’t even have enough energy to give its orbit the more typical elliptical shape seen in similar binaries. said Embry-Riddle and the lead author of the new study. statement.
Studies show that the dying star also didn’t have enough energy to force its mate out of the system.
In addition to learning more about kilonova events, this new study will help astronomers better understand the origin of the heaviest elements in the universe.
A quiet supernova occurred only a few million years ago, and astronomers expect the CPD-29 2176 system to remain intact for at least a million years or more. Their model shows that just like the first neutron star, the sibling star also becomes a supernova supernova and eventually collapses into a neutron star.
Millions of years from now, the team predicts, two neutron stars will slowly swirl closer together in a cosmic dance, eventually colliding in a kilonova explosion. Such explosions sauce Vast amounts of heavy elements such as platinum, xenon, uranium and gold were “thrown into space,” Richardson said.
Astronomers have found that heavy metals released during such events floated in the interstellar medium and coalesced into asteroids that bombarded Earth when it formed, depositing the precious metals we see today. The 2017 Kilonova event alone Sent With at least 100 times more precious metals than Earth, a failed supernova explosion doesn’t seem like a big loss to the universe after all.
This research paper (opens in new tab) It was published in Nature on Wednesday (1 February).
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