M106 - September 2012

About the image…

Image title –M106.
Taken at – Observatorio del Teide (Tenerife – Spain; 16º 30' 35" W, 28º 18' 00" N) and Observatorio del Roque de los Muchachos (La Palma - Spain; 17º 53' 30" W, 28º 45' 22" N).
Telescope – IAC80 (82cm diameter) and INT (254cm diameter).
Instrument – CCD E2V.
Focal Ratio – Cassegrain f/11.3 (IAC80) and prime f/3.29 (INT).
Exposure – Halpha: 3 x 120s (x3; INT), R: 3 x 600s (x6; IAC80), B: 3 x 600s (x6; IAC80), V: 3 x 600s (x6; IAC80).
Image size – 3x2 mosaic (IAC80), 3,500 x 5,080 pixels (17.7 x 25.7 arcmin).
Software – IRAF, PixInsight.
Images taken and reduced by –
Pablo Rodríguez-Gil, Pablo Bonet, Jorge A. Pérez Prieto and Pedro A. González Morales.
Text – Pablo Rodríguez-Gil.

About the object…

Object type – Spiral galaxy.
Equatorial Coordinates J2000.0 – 12h 18m 57.62x; +47º 18' 13.4".
Distance – 21,000,000 light-years.
Constellation – Canes Venatici.

The M106 galaxy (also known as NGC 4258) in located in the constellation Canes Venatici, very close to Ursa Major. It was discovered in 1781 by the French astronomer Pierre Mechain, and was later included in the famous catalogue of his colleague Charles Messier. M106 is a spiral galaxy around 30 thousand light-years across located only about 21 million light-years from our planet. This month’s AIM nicely shows its intricate structure, with prominent dust lanes, a bright central core, and a plethora of reddish stellar nurseries that trace the galaxy’s spiral arms. The latter have been coined ‘anomalous arms’ by many authors (see e.g. Wilson, Yang & Cecil 2001 for a description of the galaxy’s structure). In fact, M106 also shows off remarkable reddish jets of glowing hydrogen gas (seen as a red plume at the bottom left of the nucleus), actually blown out of the galactic disc by overpressured hot gas. All this phenomenology is believed to be the result of the action of a very active nucleus harbouring a massive central black hole. M106 is therefore a nearby example of the Seyfert class of active galaxies, which emit across the spectrum from radio to X-rays.