Strange ancient ‘failed stars’ found by citizen scientists
Citizen scientists recently helped direct astronomers to a pair of objects that straddle the line between planets and stars. These newly spotted substellar objects are brown dwarfs, which share many elements in common with stars. However, unlike stars these gaseous bodies don’t have enough mass to start nuclear fusion in their core, so they resemble planets more than stars.
These newfound brown dwarfs have very unusual compositions. They are the most planetlike brown dwarfs to be observed in the Milky
Way’s oldest populations of stars. They also might help researchers learn more about planets outside the Solar System.
The citizen scientists who spotted both objects were part of the ongoing NASA-funded Backyard Worlds: Planet 9 project. They were looking through spacecraft data from NASA’s WISE and NEOWISE missions; both missions are chapters in the life of a single spacecraft called the Wide-field
Infrared Survey Explorer, and the objects that the collaboration recently found, now called WISE 1810 and WISE 0414, are weird.
When scientists studied them, they were surprised to see that these two brown dwarfs have very little iron compared to what’s usually observed in brown dwarfs. This is a telltale sign that they are ancient, with each estimated to be about 10 billion years old. Both dwarfs have a mass of about 75 times the mass of Jupiter.
If these brown dwarfs formed with low levels of metal, so might ancient exoplanets. This could be a reason to search for old metal-poor exoplanets or alien worlds that orbit ancient metalpoor stars. Further research into this brown dwarf population could answer questions about how dependent the planet formation process is on the presence of metals.
NASA representatives said Backyard Worlds: Planet 9 has contributed to more than 1,600 brown dwarf discoveries.