Astronomy: a brown star

A brown star is a failed protostar that didn't turn into a star. Because of a relatively low mass (8% of our Sun's mass, or about 80 times the mass of Jupiter), the gas in its center never got hot enough to start nuclear burning, the process of turning hydrogen into helium. Although not burning hydrogen, a brown star is still quite warm with surface temperatures of 1000 - 2000 oC. For comparison, our Sun has surface temperatures of 5.500 oC and 3.700 oC for its dark sunspots . Related subject >> The first observed exoplanet orbits brown star 2M1207

A comparison of the Sun, brown star OGLE-TR-122b and gas giant Jupiter. The brown star is only 16% larger than Jupiter, but 96 times as massive. Yet, this still isn't enough to start nuclear fusion in its core.