Cracking the Dragon's Egg (NGC 6164)" by John Hayes !
NGC 6164 is located in the constellation of Norma at a distance of 3,870 ly. It’s commonly called the “Dragon’s Egg” because it sits below the famous Fighting Dragons of Ara within a nest of surrounding strong O3 and weaker H2 filaments.
It has an angular subtense of about 6.5’ x 4’ and an apparent magnitude of 6.7 so it’s a popular target for imagers with access to the Southern sky.
The core of the nebula was originally thought to be a planetary nebula but it is actually an emission nebula with an unusual origin story. The bright blue star at the center of the nebula (HD 148937) is actually two massive stars orbiting each other with a 26 year period.












