Key takeaways

  • The star, J1249+36, travels at 1.3 million miles per hour, much faster than our sun.
  • This speed could allow the star to escape the Milky Way’s gravity entirely.
  • Astronomers found this star while searching for “Planet 9” as part of a citizen science project.
  • J1249+36 is a rare, ancient L subdwarf, one of the oldest stars in the Milky Way.
  • The star’s high speed might result from a past supernova or interaction with a black hole in a globular cluster.

Astronomers discovered a jaw-droppingly fast star, one of the galaxy’s oldest, speeding across our galaxy while seeking for something else entirely.

The scientists discovered the fast star flying at 1.3 million miles per hour, roughly three times the speed of our own sun, which orbits our Milky Way galaxy at around 500,000 miles per hour.

This fast-moving star, CWISE J124909+362116.0 (“J1249+36”), could conceivably escape the galaxy’s gravity entirely. This is according to new research, which was announced during the American Astronomical Society’s 244th Meeting in Wisconsin and will be published soon in The Astrophysical Journal Letters.

fast star
A simulation of a hypothetical J1249+36-white dwarf binary pair ending with the white dwarf exploding into a supernova. This may be how the super-fast star started traveling so quickly. ADAM MAKARENKO / W.M. KECK OBSERVATORY

This discovery was found by chance, with astronomers noticing the star rushing across the galaxy while combing over data hunting for signs of “Planet 9” in our solar system. This was part of a citizen science effort called Backyard Worlds: Planet 9, in which 80,000 volunteers sifted through NASA’s Wide-field Infrared Survey Explorer (WISE) mission data from the previous 14 years in the hopes of locating a hidden planet on the boundaries of our solar system. Instead, J1249+36 was seen speeding across the galaxy at 372 miles per second.

This star’s extraordinary speed qualifies it as a prospective “hypervelocity” star, which is an incredibly unusual star that moves quickly enough to depart the galaxy entirely.

“Its speed and trajectory showed that it was moving fast enough to potentially escape the Milky Way,” researcher Adam Burgasser, an astronomy and astrophysics professor at the University of California, San Diego, said in a release.

According to the researchers’ models, the star was discovered to be a L subdwarf, a rare sort of low-mass, low-temperature star that is one of the earliest in the Milky Way.

“It was exciting to see that our models were able to accurately match the observed spectrum,” UC San Diego researcher Efrain Alvarado III said in a statement.

The exact mechanism by which this star began to travel so quickly is unknown, however scientists have proposed several ideas. One theory holds that J1249+36 was in a binary star system with a white dwarf—the residual core of a star that has expended its nuclear fuel and shed its outer layers—that gathered enough mass from its companion to erupt in a massive explosion known as a nova.

“In this kind of supernova, the white dwarf is completely destroyed, so its companion is released and flies off at whatever orbital speed it was originally moving, plus a little bit of a kick from the supernova explosion as well,” according to Burgasser. “Our calculations suggest that this scenario works. However, the white dwarf is no longer present, and the leftovers of the explosion, which occurred several million years ago, have faded, thus there is no solid proof that this is its origin.”

Alternatively, they propose that J1249+36 formed in a compact group of stars known as a globular cluster, which contained a black hole, which ended up catapulting the star at incredible speeds.

“When a star encounters a black hole binary, the complex dynamics of this three-body interaction can toss that star right out of the globular cluster,” Kyle Kremer, an assistant professor at UC San Diego, said in a release. “It demonstrates a proof of concept, but we don’t actually know what globular cluster this star is from.”

The researchers intend to continue studying the star and hunt for evidence of either scenario, such as remnants of a white dwarf nova or a globular cluster in its aftermath.

“We’re essentially looking for a chemical fingerprint that would pinpoint what system this star is from,” UC alumnus and University of Notre Dame researcher Roman Gerasimov said in a statement.

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