Tags: Star.
NGC 40 (also known as the Bow-Tie Nebula and Caldwell 2) is a planetary nebula discovered by William Herschel on November 25 1788 and is composed of hot gas around a dying star. The star has ejected its outer layer which has left behind a smaller hot star with a temperature on the surface of about 50000 degrees Celsius. Radiation from the star causes the shed outer layer to heat to about 10000 degrees Celsius and is about one light-year across.
