NASA WISE Discovers Coldest Brown Dwarf Neighbour of the Sun

This artist's conception shows a newfound object named WISE J085510.83-071442.5, the coldest known brown dwarf. 

Credit: Penn State University/NASA/JPL-Caltech

A brown dwarf as cold as the North Pole has been discovered lurking remarkably close to our solar system, and it appears to be the coldest of its kind yet found, scientists say.

Using NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope, astronomers discovered the dim, "failed star" lurking just 7.2 light-years away, making it the fourth closest system to our sun.

"It's very exciting to discover a new neighbor of our solar system that is so close," Kevin Luhman, an astronomer at Pennsylvania State University's Center for Exoplanets and Habitable Worlds, said in a statement.

"And given its extreme temperature, it should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."

This diagram illustrates the locations of the star systems closest to the sun. 

Credit: Penn State University

Brown dwarfs are sometimes called failed stars because they have many of the elements of that make up stars, but they lack the huge mass needed to kick off nuclear fusion in their core.

As a result, these objects don't radiate starlight and they sometimes resemble planets.

Some are even cool enough to have atmospheres much like gas giants.

While brown dwarfs are hidden in images taken in the visible spectrum, infrared telescopes like WISE can pick up the meager glow of brown dwarfs.

Luhman and colleagues first spotted the object in WISE data. It appeared to be moving quite fast, hinting that it was close by.

The team then investigated the object using Spitzer and the Gemini South telescope on Cerro Pachon in Chile to measure its distance and temperature.

"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 neighbours," Michael Werner, the project scientist for Spitzer at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement.

Dubbed WISE J085510.83-071442.5, our newfound neighbor is now the record-holder for the coldest brown dwarf, with a temperature between minus 54 and 9 degrees Fahrenheit (minus 48 to minus 13 degrees Celsius), Luhman and colleagues say.

The previous record holders were more tepid, chilling only to room temperature.

At 3 to 10 times the mass of Jupiter, the object also may be one of the least massive brown dwarfs ever found, the astronomers say.

Because it is so small, the scientists say it's possible that the body is actually a planet ejected from its star system, but brown dwarfs are known to be quite common cosmic objects.

The findings were described April 21 in The Astrophysical Journal.

Gemini South Telescope: A new eye to scan the sky for exoplanets

The Gemini South telescope houses the latest gear to hunt down and snap photos of exoplanets. 

Credit: Gemini Observatory, CC BY 

There is excitement in astronomy and planetary science departments worldwide as the new Gemini Planet Imager (GPI), housed in the Gemini South Telescope in the Chilean Andes, turns its razor-sharp gaze to the skies.

This device, known as GPI for short, is the first of a small handful of sophisticated instruments to attempt a task that until recently was considered all but impossible: to image the faint mote of light betraying the presence of a planet nestled against the overwhelming glare of its host star.

Planets in orbit around distant stars, exoplanets, are now known to adorn more than 1,000 star systems. There is possibly five times that number under strong suspicion awaiting only final confirmatory data to join the club.

You could be forgiven for thinking this avalanche of discovery – all coming in the past 20 years – has settled most of the important questions in exoplanetary science.

The reality, though, is it hasn't.


Location, location, location
The sample of exoplanets we now have tells us far more about the limitations of the techniques we use to find them than it does about the exoplanets themselves. We have only seen the tip of the iceberg.

The search can be likened to the proverbial scientist in a dark car park searching for a set of dropped car keys under the only streetlight.

A passer-by asks: "Did you drop your keys there?" "No," you reply. "I dropped them somewhere over there in the dark, but I can only see here."

That patch of discovery illuminated by our present instruments particularly favours the largest planets in the closest orbits about their host stars.

The extreme examples of this (and the most celebrated exoplanet discovery, of 51 Peg, that launched the field in 1995) are known as "hot Jupiters".

The name understates their inhospitable crushing gravity combined with searing radiation field from the looming host star.

In a quest to identify planets capable of supporting life hot Jupiters score low. Astronomers are working on a valuation scheme that would identify those that lie within the so-called "habitable zone".

NASA WISE: Massive black hole duo

Two black holes are entwined in a gravitational tango in this artist's conception. 

Supermassive black holes at the hearts of galaxies are thought to form through the merging of smaller, yet still massive black holes, such as the ones depicted here. 

NASA's Wide-field Infrared Survey Explorer (WISE), helped lead astronomers to what appears to be a new example of a dancing black hole duo. 

Called WISE J233237.05-505643.5, the suspected black hole merger is located about 3.8 billion light-years from Earth, much farther than other black hole binary candidates of a similar nature. 

Credit: NASA

Astronomers have spotted what appear to be two supermassive black holes at the heart of a remote galaxy, circling each other like dance partners.

The incredibly rare sighting was made with the help of NASA's Wide-field Infrared Survey Explorer (WISE).

Follow-up observations with the Australian Telescope Compact Array near Narrabri, Australia, and the Gemini South telescope in Chile, revealed unusual features in the galaxy, including a lumpy jet thought to be the result of one black hole causing the jet of the other to sway.

"We think the jet of one black hole is being wiggled by the other, like a dance with ribbons," said Chao-Wei Tsai of NASA's Jet Propulsion Laboratory, Pasadena, Calif., who is lead author of a paper on the findings appearing in the Dec. 10 issue of Astrophysical Journal.

"If so, it is likely the two black holes are fairly close and gravitationally entwined."

The findings could teach astronomers more about how supermassive black holes grow by merging with each other.

The WISE satellite scanned the entire sky twice in infrared wavelengths before being put into hibernation in 2011. NASA recently gave the spacecraft a second lease on life, waking it up to search for asteroids, in a project called NEOWISE.

The new study took advantage of previously released all-sky WISE data. Astronomers sifted through images of millions of actively feeding supermassive black holes spread throughout our sky before an oddball, also known as WISE J233237.05-505643.5, jumped out.

"At first we thought this galaxy's unusual properties seen by WISE might mean it was forming new stars at a furious rate," said Peter Eisenhardt, WISE project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and a co-author of the study.

"But on closer inspection, it looks more like the death spiral of merging giant black holes."

Almost every large galaxy is thought to harbor a supermassive black hole filled with the equivalent in mass of up to billions of suns.

How did the black holes grow so large? One way is by swallowing ambient materials. Another way is through galactic cannibalism.

When galaxies collide, their massive black holes sink to the center of the new structure, becoming locked in a gravitational tango. Eventually, they merge into one even-more-massive black hole.

More information: Preprint paper: arxiv.org/abs/1310.2257