Penn State astronomer Dr. Kevin Luhman added to his discovery list recently by identifying WISE J085510.83-071442.5, the coldest known brown dwarf in the universe and fourth-closest star to the sun.

It’s an important discovery, but perhaps better described in layman’s terms for those yet to take ASTRO 001: Brown dwarfs are born as bright stars like the sun, but they do not fuse hydrogen and therefore become dimmer as their lives progress. Luhman’s recent finding is about 100 degrees warmer than Jupiter and three-to-10 times the mass of it — very small for a star. The possibility thus exists that this star could actually be a Jupiter-like planet that fell from its star system. The star’s distance to us is also key — at 7.2 lightyears, only three known stars are closer than it to the sun, one of which was also found by Luhman.

As you’d figure, Luhman didn’t find WISE J085510.83-071442.5 overnight. He gathered images of the sky from the Wide-field Infrared Survey Explorer over several months.

“It’s very time-consuming, simply retrieving all of the data from the Internet,” Luhman said. “It was a couple terabytes of data, then processing it on my computer took a couple of months as well. It was a great deal of work to retrieve the data and process it.”

When studying the images, Luhman noticed one particularly fast-moving body (rule of thumb: The faster a body appears to move, the closer to us it probably is). He then viewed Spitzer telescope images to pinpoint its distance from us by using the parallax effect, as shown here.

The discovery also opens the door for future research.

“Because it’s as cold as a gas giant planet, that means you can use it as a laboratory for studying the properties of gas giant planets,” Luhman said. “From now on, people will probably use this cold brown dwarf to learn more about gas giant planets, even though it’s probably not a planet itself.”

As far as humans understand the universe, the new brown dwarf cannot sustain life without a solid surface or proper temperature. But it’s a big discovery, especially cool considering it came from here. Great work, Dr. Luhman!