Located about 2,400 light years away, towards the Cepheus constellation and catalogued as Sh2-155, the \"Cave Nebula\", is a diffuse Hydrogen-Alpha (Hα) emission nebula, inside a complex region of gas and dust. The hydrogen gas is ionized by the radiation of nearby young, hot stars inside the Cepheus molecular cloud and emits copious amounts of visible light with the characteristic red light. Astronomers have found that inside the nebula new stars are being born, as the radiation of the hot stars compresses the gas and triggers the star-forming process. It is a difficult object, faintly visible with a large telescope, but photographs reveal a wealth of detail, especially with the use of specialized filters.
VdB 155 is the small blue reflection nebula above and to the right of the Cave Nebula.
Telescope: Orion EON 80ED refractor, F = 500 mm, f/6.25
Camera: Canon EOS 20Da
Mount: Vixen Sphinx
Filter: Astronomik CLS
Guiding: 80/400 Skywatcher refractor - SkyWatcher SynGuider
Light frames: 20 x 5 mins (total: 100 mins), ISO 3200, Custom WB
Support frames: Darks
Date - Location: 20 - 21 September 2020 - Chalkidiki, Greece (Bortle class 4)
Processing: SiriL, StarNet, Adobe Photoshop 2021 with Astronomy Tools Actions Set (spikes added digitally to the brightest stars).