Star is discovered to be a close neighbor of the Sun and the coldest of its kind

April 25, 2014 by Whitney Clavin
This image is an artist's conception of the brown dwarf WISE J085510.83-071442.5. The Sun is the bright star directly to the right of the brown dwarf. Credit: Robert Hurt/JPL, Janella Williams/Penn State University

( —A "brown dwarf" star that appears to be the coldest of its kind—as frosty as Earth's North Pole—has been discovered by a Penn State University astronomer using NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescopes. Images from the space telescopes also pinpointed the object's distance at 7.2 light-years away, making it the fourth closest system to our Sun.

"It is very exciting to discover a new neighbor of our that is so close," said Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State and a researcher in the Penn State Center for Exoplanets and Habitable Worlds. "In addition, its extreme temperature should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."

Brown dwarfs start their lives like stars, as collapsing balls of gas, but they lack the mass to burn nuclear fuel and radiate starlight. The newfound coldest brown dwarf, named WISE J085510.83-071442.5, has a chilly temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13 degrees Celsius). Previous record holders for coldest , also found by WISE and Spitzer, were about room temperature.

Although it is very close to our solar system, WISE J085510.83-071442.5 is not an appealing destination for human space travel in the distant future. "Any planets that might orbit it would be much too cold to support life as we know it" Luhman said.

WISE J085510.83-071442.5 was discovered through its rapid motion across the sky in two infrared images the WISE satellite taken six months apart in 2010. Two additional images were taken with the Spitzer Space Telescope in 2013 and 2014 to measure its distance via the parallax effect. Credit: NASA/JPL/IPAC

"This object appeared to move really fast in the WISE data," said Luhman. "That told us it was something special." The closer a body, the more it appears to move in images taken months apart. Airplanes are a good example of this effect: a closer, low-flying plane will appear to fly overhead more rapidly than a high-flying one.

WISE was able to spot the rare object because it surveyed the entire sky twice in infrared light, observing some areas up to three times. Cool objects like brown dwarfs can be invisible when viewed by visible-light telescopes, but their thermal glow—even if feeble—stands out in .

After noticing the fast motion of WISE J085510.83-071442.5 in March, 2013, Luhman spent time analyzing additional images taken with Spitzer and the Gemini South telescope on Cerro Pachon in Chile. Spitzer's infrared observations helped to determine the frosty temperature of the brown dwarf.

This diagram illustrates the locations of the star systems that are closest to the Sun. The year when each star was discovered to be a neighbor of the Sun is indicated. The brown dwarf WISE J085510.83-071442.5 is the fourth nearest system to the Sun. Credit: Janella Williams, Penn State University

WISE J085510.83-071442.5 is estimated to be 3 to 10 times the mass of Jupiter. With such a low mass, it could be a gas giant similar to Jupiter that was ejected from its star system. But scientists estimate it is probably a brown dwarf rather than a planet since brown dwarfs are known to be fairly common. If so, it is one of the least massive brown dwarfs known.

Combined detections from WISE and Spitzer, taken from different positions around the Sun, enabled the measurement of its distance through the parallax effect. This is the same principle that explains why your finger, when held out right in front of you, appears to jump from side to side when you alternate left-eye and right-eye views.

In March of 2013, Luhman's analysis of the images from WISE uncovered a pair of much warmer brown dwarfs at a distance of 6.5 light years, making that system the third closest to the Sun. His search for rapidly moving bodies also demonstrated that the outer solar system probably does not contain a large, undiscovered planet, which has been referred to as "Planet X" or "Nemesis."

"It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the Sun's nearest neighbors," said Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion Laboratory (JPL), which manages and operates Spitzer. "This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer."

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3.7 / 5 (9) Apr 25, 2014
Cool! pun intended!
Lex Talonis
2.4 / 5 (5) Apr 26, 2014
And if it's sooooooo cold...

What could you actually do with it?

Can you land on it's surface?
1 / 5 (1) Apr 26, 2014
And if it's sooooooo cold...

What could you actually do with it?

Can you land on it's surface?

I had a somewhat similar thought. But I assume that this object would be some kind of massive gas giant that would actually behave just like a normal star, with fusion happening in the core but just not enough to heat up the mass of the object like in a normal star. I would therefore think that these brown dwarves have no surface as we know it.
5 / 5 (6) Apr 26, 2014
With Brown Dwarfs there is not stellar fusion at the core. Their mass like Jupiters is too small to sustain the proton proton reaction in main sequence stars like the sun. Their latent heat of accretion slowly decays, like Jupiter's. Some BDs "burn" a little deuterium but this chilly bugger probably doesn't.
5 / 5 (3) Apr 26, 2014
It is incorrect to claim that brown dwarves have "no" fusion in their cores. In fact, even gas giants the size of Jupiter can fuse lithium. Of course, the amount of Li in the core of any gas giant (or brown dwarf) will be miniscule and hence fusion will not be a LARGE source of heat. P-P fusion will not occur at a significant rate, so indeed the body will be cold and continue to cool.
These bodies have no hard surface, just like gas giants. You don't "land" on them. At some extreme depth there may be a solid 'surface', but you wouldn't survive at that depth, or even survive the trip to that depth.
not rated yet Apr 29, 2014
Why is the brown dwarf blue in the image?
5 / 5 (1) Apr 30, 2014
Why is the brown dwarf blue in the image?

lol, but you're kidding right?

seriously, just for the people who might really wonder about it. This kind of object shouldn't actually glow with any kind of light that your eyes can see at all. You could be standing on a spaceship in orbit very near to this thing, and all you would see is a big dark spot in the sky where there aren't any stars.

As others above have said, this thing has internal heat, just like the Earth does, but that doesn't make it glow on the outside (in visible light). Just like the Earth has a crust and a cool atmosphere around its hot center, a brown dwarf has thousands of miles of cold gas and dust surrounding its hot center. If you had a giant flashlight to shine at it, and take a look at its actual appearance, it would probably look a lot like either Jupiter/Saturn or Neptune/Uranus. If you're talking about visible color, it's an open bet right now though.
3 / 5 (2) Apr 30, 2014
Just on a personal note:

If we're taking bets on what brown dwarfs actually look like, I'm betting that there's a wide range of colors. The chemistry in the topmost visible cloud layers will determine it, and that can be any color in the rainbow, depending on just a few degrees of temp and a few bar of pressure.
3 / 5 (2) May 02, 2014
Just on a personal note:

If we're taking bets on what brown dwarfs actually look like, I'm betting that there's a wide range of colors
And why would you bet on something that science already knows a great deal about?

"Despite their name, brown dwarfs are different colours. Many brown dwarfs would likely appear magenta to the human eye according to A. J. Burgasser..."

-unless you don't much care what science already knows?

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