Horsehead - December 2012



About the image…

Image title – The Horsehead Nebula neighbourhood.
Taken at – Observatorio del Teide (Tenerife – Spain; 16º 30' 35" W, 28º 18' 00" N).
Telescope Takahashi FSQ-106ED, f/5
Instrument – SBIG STL-11000 CCD camera (H-alpha) and Canon 5D Mark II camera (colour).
Exposure – H-alpha: 18x600 s; colour: 10x600 s.
Image size 3,831 x 2,446 pixels (3.6 x 2.4 degree).
Software – IRAF, DeepSkyStacker, PixInsight.
Images taken and reduced by –
Jorge A. Pérez Prieto, Pedro A. González Morales, Pablo Rodríguez-Gil, and Pablo Bonet.
Text – Pablo Rodríguez-Gil.

Right south of the naked-eye star Alnitak (Zeta Orionis; arabic for “the girdle”) lies the nebular complex containing the famous Horsehead molecular cloud. This star-forming region is located at some 1,500 light years from Earth, and is embedded in the gigantic Orion gas cloud. It’s only visible because its obscuring material is silhouetted against the emission nebula IC 434. In contrast with the bright H-alpha glow of IC 434, the blue reflection nebula NGC 2023 (to the lower left) is powered by energetic radiation from a young, B-type star illuminating the cloud of gas and dust that gave birth to it. The stellar wind and radiation pressure from this energetic star is carving out a vast cavity within the cloud. Just to its left we can find the Flame Nebula. This time it’s Alnitak that sheds energetic light into the Flame, that strips electrons away from the great clouds of hydrogen that reside all around. Much of the glow results when the electrons and ionized hydrogen recombine.

This month’s AIM is actually a composite of many images taken with two different setups, with a total exposure time of 3 hours (STL-11000 CCD camera +H-alpha filter) and 1.7 hours (Canon 5D Mark II DSLR camera).

Back in July 2012 we presented the first light of ‘Tizón’, the new instrument of the IAC Astrophotography Group at the Observatorio del Teide: a colour portrait of the Andromeda Galaxy, M31. After a lot of work and not few problems, the new imaging system is ready. We would like to end the year with a gem of the winter sky. Season’s greetings!