Opposing the Milky Way’s rotation, the white dwarf was traveling at nearly 2 million mph (about 3.2 million km / h), which is about four times faster than our sun revolves around the galactic core. . At this speed, the star is well on its way to escape the gravitational pull of the Milky Way and enter intergalactic space.Even more remarkable, according to LiveScience, was its composition, loaded with heavy metals like oxygen, carbon, and magnesium (any atom larger than helium is considered a metal by astronomers). While it was not unusual for white dwarfs to have carbon and oxygen compositions, this star had magnesium and neon, which usually form under the intense energy of a supernova.
This led researchers in the Department of Astronomy at Boston University (BU) to study the star and piece together the puzzle of what sent it across the galaxy to its ultimate destination in the far reaches of intergalactic space. Their findings, published in The Astronomical Journal Letters, point to the catastrophic supernova.
White dwarf stars are the almshouse stage of a star’s life cycle. When a main sequence star runs out of fuel to burn during nuclear fusion, there is not enough external force to support the star’s intense mass and it collapses on itself. If a star’s mass is more than about eight times the mass of the sun, the mass is so large that the result is either a neutron star or even a black hole.
Smaller stars escape this fate, however. Their collapse sets off a catastrophic explosion known as a supernova, which scatters most of the star’s mass into a massive nebula that will help form new stars and solar systems. What remains is a bright and intensely hot shell of the star’s core, known as the white dwarf, whose mass is maintained not by fusion but by a quantum phenomenon involving electrons.
Although technically dead, with the nuclear fusion phase of the star’s life over, these stellar corpses will radiate heat and light for another billion years before going completely dark and becoming a dwarf. black. In some cases, binary star systems can end up with two white dwarfs, and this is where things get interesting.
The smaller of the two white dwarfs will begin to consume matter from the larger one, as the more massive white dwarfs are actually smaller. If a white dwarf consumes too much matter, the quantum process that keeps the star from collapsing becomes further destabilized, and the white dwarf erupts again into another violent supernova.
This is what the researchers at the BU think happened to this star.
“To have suffered a partial detonation and survive is very cool and unique, and it was only in the last few years that we started to think that this kind of star could exist,” said Odelia Putterman, a former student. from BU who co-authored the article.
“The star is actually dropped by the explosion, and we are [observing] its rotation when it comes out, ”Putterman added.
What is not known is whether the star was the partner star or a part of the star that became a supernova, although based on the speed of its rotation, the team of the BU thinks the star is essentially a shrapnel from the most massive star that has gone supernova.
“These are very strange stars,” said JJ Hermes, lead author of the article and associate professor of astronomy at the BU. “What we are seeing are the byproducts of violent nuclear reactions that occur when a star is blown up. “