Horsehead and Flame Nebulae Imaged by Donal McDonnell

The Horsehead Nebula (Barnard 33) is a dark nebula in bright nebula IC 434, in the constellation of Orion.  The Flame nebula can be seen to the bottom left of the image.

The red glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick dust.   The bright red emissions are evidence of ionized hydrogen (HII regions).  UV light is ionising clouds of molecular hydrogen; when the ionised hydrogen returns to the ground state the energy of this transition yields a wavelength of 6563A. This is in the visible red light spectrum. HII regions are known to have very strong H-Alpha

Lookup the Horsehead Nebula on SEDS

Horsehead nebula by Donal McDonnell - click to enlarge

Image taken using an Atik16HR and Takahashi FSQ106ED at F3.8 mounted on an EQ6 (with EQMOD) and guided with an ST4 on on an ED80.

• Ha 110m (11 x 600s)
• Lum: 41m
• Red: 21m
• Green 21m
• Blue 26m.