H1504+65 Documented

Date: January 27, 2011 • Location: Rome, Italy

Astronomers documented H1504+65, a white dwarf in Ursa Minor (chart pictured) with the hottest surface temperature known at the time, at 200,000 kelvins (360,000 °F).

H1504+65 is an enigmatic peculiar star in the constellation Ursa Minor. With a surface temperature of 200,000 K (360,000°F) and an atmosphere composed of carbon, oxygen and 2% neon, it is the second hottest white dwarf ever discovered, with only RX J0439.8−6809 being hotter. It is thought to be the stellar core of a post-asymptotic giant branch star, though its composition is unexplainable by current models of stellar evolution.