IC 405 (Caldwell31) is a diffuse nebula visible in the constellation of Auriga, located at 1630 light years from Earth. In its direction you can see AE Aurigae, a variable and mysterious star, according to some studies it would be a star born in the region of the Orion Nebula about 2.7 million years ago and then moved to the Milky Way from there.

IC 405 shines with the radiation received from AE Aurigae, which ionizes its gases (mainly hydrogen) and gives it a red color; the blue patches are instead due to the reflection of the blue light of the star on the dark dust. IC 405 appears to be connected with other nebulosity systems, in particular with IC 410, visible one degree to the southeast; in reality they are much more distant objects.