The WISE satellite, decommissioned this year, returned data revealing 100 new brown dwarfs, sometimes termed “failed” stars. Six of these are classified as cool Y’s.
Y dwarfs are the dimmest stars of the brown dwarf family, like all brown dwarfs, they are not massive enough to fuse atoms at their cores. Without the atomic energy that allows stars like our sun to burn for billions of years, brown dwarfs gradually cool, until they only emit infrared light.
One of the Y dwarfs found, WISE 1828+2650, now holds the record for chilliest star at 80 degrees Farenheit.
“The brown dwarfs we were turning up before this discovery were more like the temperature of your oven,” said Davy Kirkpatrick, a WISE science team member at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, California in a press release.
“With the discovery of Y dwarfs, we’ve moved out of the kitchen and into the cooler parts of the house.”
Brown dwarfs help astronomers study star formation and the atmospheres of planets like Jupiter. Their atmospheres, similar in composition to the gas-giant planets, are often easier to observe because brown dwarfs are isolated in space, away from the light of more brilliant, parent stars.
Astronomers originally chose the term “brown dwarf” because they didn’t know what colors these stars would be if we could see them, and brown isn’t a real wavelength of light. Scientists now know that some brown dwarfs would seem reddish or magenta to the eye, but they aren’t sure what color Y dwarfs would be. The purple color shown in the illustration above was chosen mainly for artistic reasons.