When huge stars die, it isn't a silent death.
Their deaths are extraordinarily magnificent events that light up the universe, a supernova explosion that sends stellar guts blasting out into space in a cloud of glory. Meanwhile, the center of the once-bright star can survive as an ultra-dense neutron star or black hole.
If the explosion occurs in just the right way, the collapsing core will scream across the Milky Way like a bat out of hell, accelerating to such crazy speeds that it will finally smash through the galaxy and into intergalactic space.
A form of pulsating neutron star known as a pulsar, tearing through its own entrails at a speed of roughly 612 kilometers per second, is one of these objects that has been freshly observed using data from the Chandra X-ray observatory (or 1.4 million miles per hour).
It's one of the most rapidly discovered objects of its type ever. (The fastest known star in the Milky Way is a star circling Sgr A*, the supermassive black hole at the galactic core, rather than a supernova remnant kicked by an explosion.) It travels at a dizzying 24,000 kilometers per second at its fastest point in its orbit.)
"We directly saw motion of the pulsar in X-rays, something we could only do with Chandra's very sharp vision," stated Harvard & Smithsonian Center for Astrophysics astronomer Xi Long (CfA).
"Because it is so distant, we had to measure the equivalent of the width of a quarter about 15 miles away to see this motion."
A bright supernova remnant designated G292.0+1.8, located 20,000 light-years distant, was used to make the discovery. A fast pulsar has been discovered there previously. Long and his colleagues sought to explore if tracking the object's velocity backwards to the object's center may give information about the supernova's past.
"We only have a handful of supernova explosions that also have a reliable historical record tied to them," said CfA astronomer Daniel Patnaude. "So we wanted to check if G292.0+1.8 could be added to this group."
They compared the variations in the pulsar's position between photos obtained in 2006 and 2016 of the supernova remnant, as well as Gaia data on its present location in the Milky Way. These comparisons showed something fascinating: the dead star appeared to be travelling 30% quicker than prior calculations indicated.
This indicates that it took a significantly shorter time to travel from the supernova remnant's center, implying that the supernova occurred much more recently. The supernova was thought to have occurred roughly 3,000 years ago, but fresh estimates place it closer to 2,000 years ago.
The team was also able to perform a fresh, in-depth research of how the dead star was blasted from the supernova's core because to the pulsar's revised velocity. They devised two scenarios, each of which included a similar process.
In the first, neutrinos are expelled asymmetrically from the supernova explosion. The debris from the explosion is expelled asymmetrically in the other. However, because the neutrino energy would have to be exceedingly high, asymmetrical debris is the most plausible explanation.
Basically, a lopsided explosion can 'kick' a dead star's collapsed core out into space at extremely high speeds; in this case, the star is currently traveling faster than the Milky Way's mid-disk escape velocity of 550 kilometers per second, though it will take a long time to get there and may slow down over time.
Because it is moving very little along our line of sight, its real speed might be considerably higher than 612 kilometers per second.
"This pulsar is about 200 million times more energetic than Earth's motion around the Sun," CfA astronomer Paul Plucinsky stated. "It appears to have received its powerful kick just because the supernova explosion was asymmetric."
