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Two enormous objects make us reconsider star evolution

A brown dwarf / Credits: NASA/JPL-Caltech

Until now it was thought that a brown dwarf with a mass 70 times greater than Jupiter transformed into a star.  However it would seem that this is in fact not the case. Two brown dwarfs, whose masses have been reevaluated, lead astronomers to reconsider star evolution.

Brown dwarfs are “failed stars”.  They are too big to be considered as planets and not big enough to support a nuclear fusion that allow stars to shine.  But at what mass does a Brown Dwarf transform into a star? At what mass can hydrogen atoms pressurize enough for an object to “ignite” and illuminate the night sky? It was previously thought that the limit was a mass 70 times greater than Jupiter which equals 1.898 × 10 ^ 27 kg.  However, two brown dwarfs whose masses have just been recalculated seem to challenge this theory.

Epsilon Indi B and C can be found about 12 light years from Earth. At our cosmic door astronomically speaking.  Discovered in 2003, the mass of these two Brown Dwarfs were initially estimated to be 48 and 28 times the mass of Jupiter. However a team from the Carnegie Institution for Science, Washington DC have recently proposed a more precise measure of the two masses by mapping the movements of the two objects in relation with their cosmic background. The results of their findings are published in the The Astrophysical Journal. According to their study the two masses are bigger than initial estimations.  Researchers now believe that Epsilon Indi B has a mass 75 times bigger than Jupiter and Epsilon Indi C has a mass 70 times bigger.

Should astronomers be reconsidering the limit that separates brown dwarfs from stars or is this just an anomaly? For the moment, researchers have reached a stumbling block. They need to carry out several observations before they can draw any concrete conclusions.  However this is a complicated business as Brown Dwarfs omit very little light making them difficult to spot. However by analysing these objects it could give us a better understanding of our galaxy.  Extraterrestrial life could potentially survive in these objects atmospheres


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