Iris Nebula NGC 7023
Object Type: Reflection Nebula
Scope: AP 5" Refractor
Exposure 265 minutes
The Iris Nebula (also known as NGC 7023 and Caldwell 4) is a bright reflection nebula in the constellation Cepheus. The designation NGC 7023 refers to the open cluster within the larger reflection nebula designated LBN 487.It is about 6 light years across and 1,300 light years away from Earth. Within the nebula, dusty nebular material (i.e.; interstellar dust and gas) surrounds a massive, hot, young star in its formative years. Central filaments of cosmic dust glow with a reddish photoluminescence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. The nebula's dominant color, blue, is the result of dust grains reflecting star light. Infrared observations indicate that this nebula may contain complex carbon molecules.
This nebula is of particular interest to scientists because of its colors. Reflection nebulae glow because they are made up of extremely tiny particles of solid matter, up to 10 or even 100 times smaller than dust particles on Earth. These particles diffuse the light around them, giving the nebula a second-hand glow that’s typically bluish (like our sky). While the Iris Nebula appears predominantly blue, it includes large filaments of deep red, indicating the presence of an unknown chemical compound likely based on hydrocarbons.