Record-breaking new brown dwarf: temperature 250 K, distance 2.2 pc

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Artistic impression (above), graphic and text credits: phys.org/Penn State

(Phys.org) —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 solar system 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 brown dwarfs, also found by WISE and Spitzer, were about room temperature.

Kevin Luhman and Penn State do it again! The preprint is in arXiv today also and the paper already published in the Astrophysical Journal, vol. 786 (2014), L18. Concerning the new object, its parallax is 0.454+/-0.045 arcseconds and the mass is likely to be in the range three to ten Jupiter masses. For more on high proper motion objects in the Wide-field Infrared Survey Explorer dataset, there is another new paper in press at ApJ, Luhman & Sheppard, preprint.

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Update: Penn State grad student Benjamin Nelson and collaborators have solved the ongoing mystery of the inner 55 Cancri system, one of the first exoplanet systems found (1997) and itself a close neighbour to the Sun, some 12 parsecs distant. Collecting together the huge dataset, Nelson has now found a dynamically plausible system of orbital resonances. Note the three massive inner planets, all closer to 55 Cnc than Mercury is to the Sun. An accurate mass for the innermost planet e was given in 2012. The outermost planet d was found in 2002 and lies further out in the system, 5.5 AU distant from the sunlike central star.

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