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M81 Galaxy Group in Ursa Major

Optics Borg ED101 at f/8.8
Camera STL11000M
Filters Baader Halpha LRGB
Date Mar 13-May 30, 2009
Location Antares Observatory
Sky Conditions mag 5 sky, moonlight for H-alpha exposures
Exposure L(Ha)RGB=750,(500),300,300,300min
total: 35h 50min
15min subexposures for LRGB and 20min for H-alpha frames
Programs used CCD-Stack, Registar, Photoshop CS4

This galaxy group clearly shows some interaction. As a result the edge-on galaxy M82 (upper right galaxy in the image) undergoes a period of high star formation indicated by the ejection of hot gas and dust perpendicular to the galaxy plane. Also, Holmberg IX (just above the central galaxy M81) is a result of the tidal interaction between M81 and M82. It consists of torn out stars and dust.

To the right of M82 a very far distant galaxy cluster (NSC J095337+694751 with z=0.211) is visible. This light has been travelling for about 2.5 Billion years!

The third prominent galaxy in the field of view is NGC3077 (to the left in the image). This galaxy is cataloged as an irregular galaxy lying at a distance of 12.5 Million lightyears, also interacting with the central galaxy M81. The whole Galaxy Group contains about 60 galaxies.

Beside these galaxies the whole image is covered by very faint dust bands. This structure is known as the Galactical Cirrus or Integrated Flux. These dust particles are illuminated by the light of the milkyway (our galaxy) and are therefore not connected to the M81 Galaxy Group.

M81 Galaxy Group

click here for a 50% size 1799x1220 (1080KB)

Click on the images below to find a black and white version for a better visibility of the Integrated Flux (538KB)

Integrated Flux

The images below show you a 80% view of the M81 and M82 galaxies (429KB)

M81 and M82

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