60-Second Space

Chilly, Chilly, Little Star

A brown dwarf only about three to 10 times Jupiter's mass couldn't get fusion going and now sits freezing in space, in the nearby galactic neighborhood. Clara Moskowitz reports


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

[The above text is a transcript of this podcast.]

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