科学美国人60秒:Chilly, Chilly, Little Star

Call this story, “A star is stillborn.”

The object is a brown dwarf, which started off the same way that more conventional stars form, but which lacked the mass required for nuclear fusion to ignite and radiate starlight. What resulted was a body somewhere in between a star and a planet.

It was spotted recently by NASA’s WISE and Spitzer space telescopes. And it’s been dubbed WISE J085510.83-071442.5. So let’s not say its name again, okay?

At only about three to 10 times the mass of Jupiter, this WISE guy is small even for a brown dwarf. It’s the fourth-nearest star system, just 7.2 light-years away. And it’s freezing—about as cold as the North Pole. K.L. Luhman, Discovery of a ~250 K Brown Dwarf at 2 pc from the Sun, in Astrophysical Journal Letters]

Temperatures on this body range from a frosty minus 54 to plus 9 degrees Fahrenheit. For comparison, the sun’s surface is a toasty 10,000 Fahrenheit.

Noticing such a cold object in space that radiates almost no light would be impossible with visible-light telescopes. Its dim thermal glow was just barely discernible to the infrared eyes of WISE and Spitzer. And its name ensures mostly continued anonymity.

—Clara Moskowitz