Bow-Tie (NGC 40)

Object Type: Planetary Nebula
Scope: C-9.25" SCT; Exposure 105 minutes.

NGC 40 (the Bow-Tie Nebula, Caldwell 2) is a planetary nebula in Cepheus, about 3,500 light-years away, discovered by William Herschel in 1788. It is the glowing outer layers of a dying star, cast off to leave a hot central remnant with a surface temperature around 50,000 degrees. Radiation from that star heats the surrounding shell, which is roughly one light-year across. In about 30,000 years the nebula is expected to fade, leaving behind an Earth-sized white dwarf.