[LINK] "Cooler-Than-Steam Brown Dwarf Blurs The Line Between Star & Planet"

[rfmcdonald]

This concerns CFBDSIR J1458+1013 ab, a very dim pair of brown dwarfs literally located beyond Arcturus. But are they both brown dwarfs?

CFBDSIR J1458+1013B [. . .] may be cooler than the boiling point of water (at the pressure of Earth’s atmosphere). This strange body is about 75 light-years from us, where it orbits its binary partner, another brown dwarf. Using the infrared capabilities of the 10-meter Keck II Telescope on Mauna Kea, University of Hawaii researcher Michael Liu and his team estimated the brown dwarf’s temperature, and have a ballpark range for its mass: between 6 and 15 times the mass of Jupiter.

It’s special because it may be a class Y dwarf (temperature less than 225 degrees Celsius (440 F)), a type of object whose existence astronomers had predicted but never actually found. Before this candidate arose, the coolest known brown dwarf was in the T spectral class; while there have been a few Y-class candidates in the past, scientists have a better grasp on the temperature of this one: 97 degrees Celsius, plus or minus 40C.

Another cool (ahem) thing about this particular brown dwarf is its mass. An object less than 13 Jupiter masses is too light to fuse atoms of deuterium, a heavy isotope of hydrogen; objects above 13 Jupiter masses can fuse deuterium. The uncertainty over CFBDSIR’s mass—estimated as between 6 and 15 Jupiter masses—could put it on either side of the line. And to top it off, it may be so cool that its gases could form clouds, a very planet-like thing to do.

Yay! interstitial objects!