If you were attacked by a greedy vampire star or risked falling into two dueling black holes, you’d probably run away too!
One of these terrifying scenarios is likely responsible for sending a low-mass star across the Milky Way at a staggering million miles per hour (1.6 million kilometers per hour). This is approximately 1,500 times faster than the speed of sound.
The star has been named CWISE J124909+362116.0 (J1249+36) and was first detected by citizen science volunteers from the Backyard Worlds: Planet 9 project, which investigated large amounts of data collected by NASA’s Wide Field Infrared Survey Explorer (WISE). a mission of almost a decade and a half. J1249+36 stood out immediately because of its particularly tremendous speed of 1.3 million mph (2.1 million km/h), nearly three times the speed of the sun in its orbit around the heart of the Milky Way. The speed of this “ultrafast” star is so great that it is likely to escape our galaxy entirely.
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To unravel the secrets of this hyperfast star, Adam Burgasser, Professor of Astronomy and Astrophysics at the University of California, San Diego, returned to the WM Keck Observatory in Maunakea, Hawaii, to observe its infrared spectrum.
This research revealed that the star belongs to the oldest class of stars in the Milky Way: L subdwarfs. These stars are very rare and remarkable due to their extremely low mass and relatively cold temperatures.
The team’s spectral data were combined with a new set of atmospheric models created specifically to study L subdwarfs. This revealed the position and speed of J1249+36 in the Milky Way. “This is where the resource becomes very interesting,” Burgasser said in a statement. “Its speed and orbit indicated that it was moving fast enough to have the potential to escape the Milky Way.”
The question is: What pushed this semi-dwarf star into a fast escape orbit? This brings us to our two suspects.
Is this star running from a white dwarf vampire?
In the first scenario used to explain the hypervelocity nature of J1249+36, Burgasser and colleagues hypothesized that the low-mass star was once the stellar companion of a “dead” type of star called a white dwarf.
White dwarfs are born as a result of smaller stars like the Sun exhausting the hydrogen supply in their cores. When this happens, the star’s nuclear fusion stops. This cuts off the outward flow of energy that supports the star against the inward pressure of its own gravity. While this ends the lives of lonely, isolated stars like the Sun, white dwarfs in binary systems can return from the grave by cannibalizing stellar material scraped from a nearby “donor” star.
This material accumulates on the white dwarf until the mass of the stellar remnant exceeds the Chandrasekhar limit, which is about 1.4 times the mass of the Sun at which a star can go supernova. This results in a type of cosmic explosion called a “Type Ia supernova” that completely destroys the white dwarf.
“In this type of supernova, the white dwarf is completely destroyed, so its companion is released and flies away according to the orbital speed at which it was initially moving, it is also slightly affected by the supernova explosion,” Burgasser explained. “Our calculations show that this scenario works. But the white dwarf is no longer there, and the remnants of the explosion that likely occurred several million years ago have long since disappeared, so we have no conclusive evidence that this is it.” Origin.”
Could twin black holes have something to do with this?
In the second scenario considered by the team, this hyperfast star is predicted to begin its life in a globular cluster, a dense and compact cluster of stars bound together by gravity. These globular clusters can contain anywhere from tens of thousands to millions of stars.
Stars are concentrating towards the center of globular clusters, where scientists theorize black holes of different masses also hide. These black holes can come together and form binaries that are adept at blasting stars that get too close out of their systems.
“When a star encounters a black hole binary, the complex dynamics of this three-body interaction can blow that star out of the globular cluster,” said Kyle Kremer, an assistant professor in the Department of Astronomy and Astrophysics at UC San Diego. said.
Simulations created by Kremer revealed that in rare cases, such interactions can knock a low-mass subdwarf out of the globular cluster and place them in orbits similar to the one observed with J1249+36.
The team also tracked the orbit of this hypervelocity star into an extremely populated region of space; This region may or may not be the location of a currently undiscovered globular cluster. more than one.
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The team will now look at the elemental composition of J1249+36 to determine which of these launch scenarios is correct. Composition may be an indicator of possible origin because white dwarfs contaminate the stars they eject when they “go nova.” In addition, stars born in globular clusters have different chemical compositions.
Whatever the origin of this star, its discovery offers scientists a unique opportunity to investigate hypervelocity stars as a whole. And it’s all very nice.
Burgasser presented the team’s results at a press conference during the 244th national meeting of the American Astronomical Society (AAS) on Monday, June 10, in Madison, Wisconsin.