At 1.4 million mph, astronomers detect one of the fastest cosmic objects of its kind

When massive stars die, they don’t do so quietly.

His death is the spectacularly brilliant case that lights up the universe, a supernova explosion that sends the star swooping through space in a cloud of splendor. Meanwhile, the core of the star—all that could have remained—collapsed into an ultra-dense neutron star or black hole.

If that explosion happens a certain way, it could send collapsed cores barreling across the galaxy like a bat out of hell, at such insane velocities that they may eventually be completely cleared of the galaxy, wild in intergalactic space. on a tour .

It is one of these objects that has been measured via data from the Chandra X-ray Observatory: a type of pulsating neutron star known as a pulsar, with a speed of about 612 kilometers per second (or 1.4 million miles). per hour ripping through its own entrails).

It is one of the fastest such objects ever discovered. (The fastest known star in the Milky Way is not a supernova remnant kicked off by an explosion, but a star orbiting Sgr A*, the supermassive black hole at the galaxy’s center. At the fastest point in its orbit, It accelerates to a wild 24,000 kilometers per second.)

“We directly observed the motion of the pulsar in X-rays, which we could only do with very fast vision of Chandra,” said astrophysicist Xi Long of the Harvard and Smithsonian Center for Astrophysics (CFA).

“Because it is so far away, we had to measure about 15 miles away to see this speed, equal to the width of a quarter.”

It was detected by observing a bright supernova remnant about 20,000 light-years away named G292.0+1.8. Previous observations had revealed a fast pulsar in it. Long and his colleagues wanted to study the object to see if it could reveal the history of a supernova, by reversing its motion at the object’s center.

“We have only a few supernova explosions that even have a reliable historical record associated with it,” said CFA astrophysicist Daniel Patnaude, “so we wanted to test whether G292.0+1.8 could be added to this group.” could.”

They studied images taken from supernova remnants in 2006 and 2016 and used Gaia data at their current location in the galaxy, comparing differences in the positions of the pulsars. These comparisons revealed something very interesting: the dead star appears to be moving 30 percent faster than previous estimates.

This means that the supernova has taken very little time to travel from the center of the remnant, suggesting that the supernova itself was very recent. Previous estimates put the date of the supernova at about 3,000 years ago; New estimates take it to about 2,000 years ago.

The pulsar’s modified velocity also allowed the team to conduct a new, detailed investigation of how the dead star may have been ejected from the supernova’s center. They came up with two scenarios, both of which involved a similar mechanism.

In the first, neutrinos are ejected asymmetrically from a supernova explosion. in other, debris is ejected asymmetrically from the explosion. However, because the neutrino energy would need to be very large, the more likely explanation is heterogeneous debris.

Basically, a one-off explosion can ‘kick’ the collapsed core of a dead star into space at extremely high speeds; In this case, the star is currently traveling at speeds exceeding the Milky Way mid-disk escape velocity of 550 kilometers per second, although it will take a long time to get there, and it may slow down over time.

In fact, its actual speed may exceed 612 kilometers per second, as it is traveling very little along our line of sight.

“This pulsar is about 200 million times more energetic than Earth’s motion around the Sun,” said astrophysicist Paul Plucinsky of the CFA. “It looks like it got its powerful kick because the supernova explosion is asymmetric.”

The team’s research, presented at the 240th meeting of the American Astronomical Society, has been accepted. The Astrophysical Journal and is available on arXiv.


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