The Coldest 'Brown Dwarf' Star Discovered Lives Close To Our Solar System
Numerous stars and dwarfs are discovered each year, but the latest "brown dwarf" to be observed in our cosmic neighborhood has the distinction of being the coldest of its kind. The star, discovered by a Penn State University astronomer using NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescopes, may be as ice-covered as the Earth's North Pole. It's not very far, either, at just 7.2 light years away, it's the fourth closest celestial system to our Sun.
Like Us on Facebook
"It is very exciting to discover a new neighbor of our solar system that is so close," said Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State, in a statement. "In addition, its extreme temperature should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."
Brown dwarfs are not quite stars. They are substars, whose low mass only allows them to sustain partial nuclear fusion, unlike main sequence stars that can sustain hydrogen-1 fusion reactions in their cores. This frosty brown dwarf, named WISE J085510.83-071442.5, has a chilly temperature between negative 54 and nine degrees Fahrenheit. That means that it is much colder than the brown dwarf previously believed to be the coldest, which had an environment close to room temperature. With the star being so cold, astronomers are certain that planets orbiting it would also be much too cold to support life.
"This object appeared to move really fast in the WISE data. That told us it was something special," Luhman said in the statement. That was because a closer celestial body appears to move more in images that are taken months apart - similar to the way a low-flying airplane appears to move faster than when it is at a higher altitude.
Brown dwarfs are generally difficult to come by because their low luminosity makes them impossible to detect when viewed by visible-light telescopes. But WISE uses infrared light to scan the entire sky twice, and sometimes thrice. The brown dwarf stood out in the infrared light even with its feeble glow. After noticing the cold dwarf in March 2013, Luhman spent time additional time analyzing images taken with the Spitzer and the Gemini South telescope on Cerro Pachon in Chile. Spitzer's infrared observations helped determine its frosty temperature.
Brown dwarfs are generally just a little larger than planets, and the newly discovered dwarf is three 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. Yet, scientists are sticking to their claim that it's a dwarf, as they tend to be more common.
Combining the observations of WISE and Spitzer, taken from different positions around the Sun, enabled the measurement of its distance through the parallax effect - the same principle that explains why your finger, when holding it up in front of you, appears to jump from side to side when you alternate between left-eye and right-eye views.
In March 2013, Luham discovered a couple of warm brown dwarfs at a distance of 6.5 light years, the third closest system 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), in the statement. "This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer."
© 2012 iScience Times All rights reserved. Do not reproduce without permission.