Elephant's Trunk Nebula (IC 1396A)

This iconic emission nebula is a striking region of active star formation embedded within the much larger IC 1396 emission complex in the constellation Cepheus. The dark “trunk” seen in the image is a dense column of cold molecular gas and dust being shaped by radiation and stellar winds from nearby massive stars. These processes slowly erode the cloud while simultaneously compressing parts of it, triggering the collapse of gas pockets that form new stars.

Located roughly 0.7 kpc (~2400 light-years) from Earth, the nebula lies within a large star-forming region spanning a few pc across. Several young protostars are forming inside the dark clumps, hidden from visible light but detectable in infrared observations. The curled tip of the trunk and surrounding ridges show the interface where ultraviolet radiation from nearby hot stars ionises the surrounding hydrogen gas.

What we see glowing in the nebula is primarily ionised gas. High-energy ultraviolet photons from massive stars strip electrons from atoms in the surrounding cloud, creating a plasma that emits light at very specific wavelengths. These emissions give the nebula its characteristic colours when captured with narrowband filters. Oxygen-III (500.7 nm), H-alpha (656.3 nm), and Sulfur-II (672.4 nm) filters were used for this image. The colours of the stars were obtained with normal RGB filters.

The image was captured from Leysin, Vaud (Switzerland) using a Takahashi TOA-150 refractor telescope with an aperture of 150mm and a focal length of 1.1m. 
 
Aurel Schneider 2024