H1504+65 is an enigmatic peculiar star in the constellation

Ursa Minor Ursa Minor (, contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern celestial hemisphere, northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of ...

. 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 A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

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 Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is consi ...

References

White dwarfs Ursa Minor {{whitedwarf-star-stub