Nearby Failed Star Binary May Hide Alien World
WISE J104915.57-531906 is at the center of the larger image, which was taken by the NASA's Wide-field Infrared Survey Explorer (WISE). This is the closest star system discovered since 1916, and the third closest to our sun. It is 6.5 light-years away.
Image: Kepler-16b is the first exoplanet disc
Exquisite Exoplanetary Art
Sept. 19, 2011 --
They're alien worlds orbiting distant stars far out of reach of detailed imaging by even our most advanced telescopes. And yet, day after day, we see vivid imaginings of these extrasolar planets with the help of the most talented space artists. The definition of an extrasolar planet -- or "exoplanet" -- is simply a planetary body orbiting a star beyond our solar system, and nearly 700 of these extrasolar worlds have been discovered so far (plus hundreds more "candidate" worlds). With the help of NASA's Kepler space telescope, the ESO's High Accuracy Radial velocity Planet Searcher (HARPS), French COROT space telescope and various other advanced exoplanet-hunting observatories, we are getting very good at detecting these worlds, but to glean some of the detail, we depend on artist's interpretations of fuzzy astronomical images and spectral analyses. That's the way it will be until we build a vast telescope that can directly image an exoplanet's atmosphere or physically travel to an alien star system. So, with the flurry of recent exoplanet discoveries, Discovery News has collected a few of the dazzling pieces of art born from one of the most profound searches mankind has ever carried out: the search for alien worlds orbiting other stars; a journey that may ultimately turn up a true "Earth-like" world.
Image: An exoplanet passes in front of (or "t
As an exoplanet passes in front of its star as viewed from Earth, a very slight dip in starlight brightness is detected. Observatories such as NASA's Kepler space telescope use this "transit method" to great effect, constantly detecting new worlds.
Some exoplanets orbit close to their parent stars. Due to their close proximity and generally large size, worlds known as "hot Jupiters" are easier to spot than their smaller, more distant-orbiting cousins.
Image: An artist's impression of Gliese 581d,
The primary thrust of exoplanet hunting is to find small, rocky worlds that orbit within their stars' "habitable zones." The habitable zone, also known as the "Goldilocks zone," is the region surrounding a star that is neither too hot nor too cold. At this sweet spot, liquid water may exist on the exoplanet's surface. Where there's water, there's the potential for life.
Credit: David A. Aguilar (CfA)
Usually, exoplanet hunters look for the slight dimming of a star or a star's "wobble" to detect the presence of an exoplanet. However, in the case of Kepler-19c, its presence has been detected by analyzing its gravitational pull on another exoplanet, Kepler-19b. Kepler-19c is therefore the Phantom Menace of the exoplanet world.
Image: A cool world some distance from its st
The habitable zone seems to be the pinnacle of extraterrestrial living. If you're an alien with similar needs to life on Earth, then you'll need liquid water. If your planet exists outside your star's habitable zone, well, you're in trouble. Either your world will be frozen like a block of ice, or boiling like a kettle. But say if your world had the ability to extend your star's habitable zone? There may be some atmospheric factors that might keep water in a comfy liquid state. Even better, if you like deserts, a dry world could even be oddly beneficial.
Image: A "hot Jupiter" and its two hypothetic
Planets with a global magnetic field, like Earth, have some dazzling interactions with the winds emanating from their stars. The high-energy particles bombard the planet's atmosphere after being channeled by the magnetism. A wonderful auroral lightshow ensues. But say if there's an exoplanet, with a magnetosphere, orbiting really close to its star? Well, stand back! The entire world would become engulfed in a dancing show, 100-1000 times brighter than anything we see on Earth.
Credit: Adrian Mann, <a href="http://www.bisb
"Candidate" exoplanets are often mentioned, especially when talking about detections by the Kepler space telescope. But what does this mean? As a world passes in front of its star, slightly dimming the starlight, this isn't considered a "confirmed" exoplanet detection. To make sure that signal is real, more orbital passes of the exoplanet need to be logged before a bona fide discovery can be announced. Until then, these preliminary detections are called exoplanet candidates.
Image: An exoplanet being destroyed by X-rays
Angry Suns, Naked Planets
Exoplanets come in all sizes and all states of chaos. Some might have wonky orbits, others might be getting naked. Other times, they're simply being ripped apart by X-rays blasted from their parent star. Bummer.
Image: Artist's impression shows HD 85512b, a
Super-Earths get a lot of press. Mainly because "Earth" is mentioned. Sadly, most of these worlds are likely completely different to anything we'd call "Earth." And you can forget calling the vast majority of them "Earth-like." It's simply a size thing -- they're bigger than Earth, yet a lot smaller than Jupiter, hence their name, "super-Earth." Easy.
Credit: Adrian Mann, <a href="http://www.bisb
For now, we have to make do with artist's renditions of exoplanets for us to visualize how they may look in their alien star systems. However, plans are afoot to send an unmanned probe to an interstellar destination. Although these plans may be several decades off, seeing close-up photographs of these truly alien worlds will be well worth the wait.
Astronomers have spotted signs of a possible exoplanet in a nearby system of twin failed stars. If confirmed, the alien world would be one of the closest to our sun ever found.
Scientists only discovered the pair of failed stars, known as brown dwarfs, last year. At just 6.6 light-years from Earth, the pair is the third closest system to our sun. It's actually so close that "television transmissions from 2006 are now arriving there," Kevin Luhman, of Penn State's Center for Exoplanets and Habitable Worlds, noted when their discovery was first announced in June.
The brown dwarf system, which has been dubbed Luhman 16AB and is officially classified as WISE J104915.57-531906, is slightly more distant than Barnard's star, a red dwarf 6 light-years away that was first seen in 1916. Even closer to our sun is Alpha Centauri, whose two main stars form a binary pair about 4.4 light-years away. The alien planet Alpha Centauri Bb is known to orbit one of the stars in the Alpha Centauri system, and currently holds the title of closest exoplanet to our solar system. [The Strangest Alien Planets Ever Found (Gallery)]
The brown dwarfs were spotted in data from NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft, which took about 1.8 million images of asteroids, stars and galaxies during its ambitious 13-month mission to scan the entire sky. Brown dwarfs are sometimes called failed stars because they are bigger than planets but don't enough mass to kick-off nuclear fusion at their core.
Henri Boffin of the European Southern Observatory (ESO) led a team of astronomers seeking to learn more about our newfound dim neighbors. The group used the very sensitive FORS2 instrument on ESO's Very Large Telescope at Paranal in Chile to take astrometric measurements of the objects during a two-month observation campaign from April to June 2013. (Astrometry involves tracking the precise motions of a star in the sky.)
"We have been able to measure the positions of these two objects with a precision of a few milli-arcseconds," Boffin said in a statement. "That is like a person in Paris being able to measure the position of someone in New York with a precision of 10 centimeters."
The group discovered that both brown dwarfs in the system have a mass 30 to 50 times the mass of Jupiter. (By comparison, our sun's mass is about 1,000 Jupiter masses.) Because their mass is so low, they take about 20 years to complete one orbit around each other, the astronomers said.
Boffin's team also discovered slight disturbances in the orbits of these objects during their two-month observation period. They believe the tug of a third object, perhaps a planet around one of the two brown dwarfs, could be behind these slight variations.
"Further observations are required to confirm the existence of a planet," Boffin aid in a statement. "But it may well turn out that the closest brown dwarf binary system to the sun turns out to be a triple system!"
So far, only eight exoplanets have been discovered around brown dwarfs, and they were found through microlensing and direct imaging, the astronomers say. The team added that the potential planet in Luhman 16AB could be the first alien discovered using astrometry if confirmed.
The research was detailed in a letter to the editor in the journal Astronomy and Astrophysics. It is available online on the preprint site Arxiv.
More from SPACE.com:
7 Ways to Discover Alien Planets
Images: Closest-Ever Alien Planet, the Earth-Size Alpha Centauri Bb
Alien Planet Quiz: Are You an Exoplanet Expert?
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