Bode's Galaxy - June 2012



About the image…

Image title – Bode's Galaxy.
Taken at – Observatorio del Teide (Canary Islands – Spain; 16º 30' 35" W, 28º 18' 00" N).
Instrument – IAC80 (82cm diameter).
Exposure – B: 3 x 600s, V: 3 x 600s, R: 3 x 600s, Hα: 3 x 600s, each image.
Image size –  2x2 mosaic,  about 18x18 arcminutes.
Software – IRAF, PixInsight, Photoshop CS5.
Images taken and reduced by –
Pablo Rodríguez-Gil, Pablo Bonet, Jorge A. Pérez Prieto and Roger Gimeno.
Text – Pablo Rodríguez-Gil and Jorge A. Pérez Prieto.

M81 and M82 form one of the most spectacular galaxy pairs in the northern sky. A small telescope or even a good pair of binoculars are enough to observe this pair of galaxies. Only 38 arcmin apart in the constellation Ursa Major this couple was discovered by German astronomer Johann E. Bode in December 1774 from Berlin. The main galaxy, the majestic M81, is a Sab spiral shining at 7th magnitude. Its arms are plagued with blue giant stars and enormous starburst regions that reveal themselves with the characteristic red colour of hydrogen (H-alpha) emission. M81 harbours an active core showing Seyfert-like characteristics that produces variable X-ray and radio emission, suggesting that a central gigantic black hole powers the whole system. Thanks to its proximity, about 12 million light years away, M81 is one of the best studied active nucleus galaxies.

M81 is located approximately at the centre of the so-called M81 Group of Galaxies, which contains a dozen galaxies, including M82. This group together with the Sculptor Group of Galaxies in the Southern Hemisphere is the nearest neighbour to our Local Group of galaxies.

Only one supernova explosion has ever been recorded in M81, but it was the second brightest of the last century, after SN1987A in the Large Magellanic Cloud. Supernova SN1993J was discovered by Spanish amateur Francisco García in March 1993 and showed a peculiar behavior. It was initially classified as a type-II supernova and then evolved into type Ib. It was eventually classified as a type-IIb, hydrogen-poor and helium-rich supernova.