M81 + M82   -   Bode's Nebula + Cigar Galaxy

Full resolution (1600x1200 px  530kB)

Object identification (1600x1200 px  530kB)

Inverted image of galactic cirrus (430kB)

Object data

Object type: galaxy group (M81: Sb  /  M82: Irr)
Size: M81: 24.9'x11.5'   /  M82: 11.2'x4.3'
Magnitude: M81: 7.8m  /  M82: 9.3m
Constellation: UMa
Distance: M81: 18 MLy  /  M82: 13 MLy

The M81 group shows clear signs of interaction. One effect is a very high rate of star formation in M82. A collective outgassing of stellar winds and supernovae led to the ejection of the strong Ha streamers. The irregular dwarf galaxy Holmberg IX (below M81 in the above image) is another sign for the interactions in this galaxy group. It is assumed that Holmberg IX condensed from tidal debri existing between M81 and M82.

The small, red emission nebula below Holmberg IX was initially thought to consist of two distinct HII regions: MH9 and MH10, catalogued by Miller & Hodge in 1994. Now, it is clear that this emission nebula is one bright Ha shell with a diameter of 1,500 Ly, which is called MH9/10.

Above M82, one can find the distant galaxy cluster NSC J095337+694751 (z=0.211; light travel time 2.5 Gyr).

Galactic Cirrus, also known as Integrated Flux Nebula is spread over the whole image field. This faint nebula is not connected with the M81 group, but is a part of our milky way.

Exposure data

Date: 2007-04-11 + 12 + 13 +14 + 15 +16 +17
Location: Schlierbach / Austria (400m)
Telescope: TeleVue NP101 (4" Apo f=540mm)
Camera: ST2000XM with CFW8 and SBIG Filters + Astronomik Ha 13nm
Binning: L 1x1   /   Ha 1x1   /   RGB 2x2
Exposure time: L 27x24m / Ha 22x24m / R 9x24m / G 9x12m / B 9x12m
Exposure time total: 26h 48m  (LRGB18h 00m / Ha 8h48m)
Notes: Image orientation: North is left.