Astronomers Named This Failed Star 'The Accident,' And For Good Reason
Due to a rather fortunate accident, a team of astronomers may have discovered a method to identify older brown dwarf stars. Unlike stars like our Sun, brown dwarfs are a type of star that does not have the mass needed to sustain internal nuclear fusion. About 2,000 brown dwarfs are known to exist in the Milky Way galaxy, but it is believed that they are much more plentiful.
Most brown dwarfs have a mass 13-80 times the mass of the gas giant Jupiter. Because brown dwarfs cannot support nuclear fusion and ignite in the way that a true star does, they become cooler as they age and radiate light at wavelengths imperceivable to the human eye. However, the star known as WISE 1534-1043, or “The Accident,” has shown researchers that there is still more to learn about brown dwarfs.
Discovered by scientist Dan Caseleden as he was trying to remove stationary distant stars from a map made by NASA’s Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE), the brown dwarf appeared quite literally out of nowhere. According to NASA, Caseleden was looking at a potential brown dwarf to remove from the map when he spotted another object moving quickly across the screen. The Accident had not been identified as a brown dwarf by NEOWISE, because its composition did not match what the program was taught to catalog as a brown dwarf. Using the tools available at the W.M. Keck Observatory, the team was only able to get a faint view of the object, which they believed meant it was farther out from Earth. But the Hubble and Spitzer Space Telescopes were able to pick up a clearer view of the star and confirmed The Accident is only 50 light-years from Earth, it is just moving very quickly at about “half a million miles per hour.” Because of the star’s apparent age, the team theorized that the star is 10-13 billion years old.
According to the team's study of The Accident, there are four potential theories about its origins. The most likely is that the star is an “extremely low metallicity (old) brown dwarf” which would account for how it has picked up so much speed and why it was nearly impossible to detect. It could also be an “extremely low mass, low gravity (young) brown dwarf” but that would not account for the chemical composition of the star. The third and fourth theories consider that The Accident is an “ejected exoplanet” or “ultracold stellar remnant” but the team was not able to reconcile how an object of its size is so close to our system.
The takeaway is that The Accident might be the oldest Y-type subdwarf star recorded, and the makeup of brown dwarfs is more varied than previously thought. With this, researchers can begin looking for previously unidentified brown dwarfs throughout the galaxy, and potentially revealing solar systems that might have supported life, but fizzled out as the star they collected around cooled.
Sources: NASA, The Astrophysical Journal Letters