Dwarf survives in stellar furnace

[Rick]

A distant world that escaped the likely fate of the Earth - being fried when the Sun grows old and dies - has been discovered by UK astronomers.

The brown dwarf withstood being swallowed by a red giant and is now locked in a perpetual dance with the remains of the larger star.

More: http://news.bbc.co.uk/1/hi/sci/tech/5235306.stm

[Rick]

A class of "failed" star called a brown dwarf emits beams of radiation that are thousands of times brighter than any released by the Sun.

The brown dwarfs are behaving like an altogether different and exotic cosmic object called a pulsar.

Pulsars are rotating neutron stars that emit a flashing radio signal.

More: http://news.bbc.co.uk/2/hi/science/nature/6574433.stm

[Rick]

Astrophysicists have found a star-like object with a surface temperature just one tenth that of the Sun.

The cold object is known as a brown dwarf: a "failed" star that never achieved the mass required to begin nuclear fusion reactions in its core.

This one - called J0034-00 - is thought to have a surface temperature of just 600-700 Kelvin (up to 430C/800F).

More: http://news.bbc.co.uk/2/hi/science/nature/6720831.stm

[Rick]

The European planet-hunter Corot has spotted an object orbiting a star that is quite unlike anything seen before.

It is about the size of Jupiter, but packs more than 20 times the mass.

Scientists say they are not sure if the object is a planet or a type of failed star known as a brown dwarf - neither description really seems to fit.

The Corot orbiting observatory detected the object by the way it dimmed the light of its parent star as it moved in front of its disc, as seen from Earth.

The odd-ball has been designated Corot-exo-3b. It takes just four days and six hours to orbit its parent star, which is slightly larger than our Sun.

The object's size, close proximity and short orbit made it easier to detect.

More: http://news.bbc.co.uk/2/hi/health/7656528.stm

[Rick]

"Failed Stars" Host Powerful Auroral Displays

Caltech astronomers say brown dwarfs behave more like planets than stars

Brown dwarfs are relatively cool, dim objects that are difficult to detect and hard to classify. They are too massive to be planets, yet possess some planetlike characteristics; they are too small to sustain hydrogen fusion reactions at their cores, a defining characteristic of stars, yet they have starlike attributes.

By observing a brown dwarf 20 light-years away using both radio and optical telescopes, a team led by Gregg Hallinan, assistant professor of astronomy at Caltech, has found another feature that makes these so-called failed stars more like supersized planets—they host powerful auroras near their magnetic poles.

The findings appear in the July 30 issue of the journal Nature.

More: http://www.caltech.edu/news/failed-stars-host-powerful-auroral-displays-47428
(Also in the Guardian)

[Rick]

Powerful Auroras Found at Brown Dwarf

Brown dwarfs are generally cool, dim objects, but their auroras are about a million times more powerful than auroras on Earth, and if we could somehow see them, they'd be about a million times brighter, Hallinan said. Additionally, while green is the dominant color of earthly auroras, a vivid red color would stand out in a brown dwarf's aurora because of the higher hydrogen content of the object's atmosphere.

The foundation for this discovery began in the early 2000s, when astronomers began finding radio emissions from brown dwarfs. This was surprising because brown dwarfs do not generate large flares and charged-particle emissions the way the sun and other kinds of stars do. The cause of these radio emissions was a big question.

More: http://www.jpl.nasa.gov/news/news.php?feature=4676