The Whale Galaxy (NGC 4631)

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About this Image

NGC 4631 is a big beautiful spiral galaxy seen edge-on at 25 million light-years distance. It is situated within the small northern constellation Canes Venatici. This galaxy's distorted shape suggests a huge cosmic whale and is so called the Whale Galaxy. It is similar in size to our own Milky Way.

The galaxy is accentuated by dark dust lanes across the galactic plane, it shows young bright blue star clusters and red star forming regions glowing in ionisized Hydrogen gas. The small elliptical NGC 4627 appears below the Whale Galaxy as companion.
Just out of the field of this image another distorted galaxy is situated, the hockey stick-shaped NGC 4656. The distortions and the wide unsymmetric halo suggest that all three galaxies have had close encounters with each other in their past.
North is down;

Below you see a crop on the center of the above image in 35/80% size.

Literature:
Chandra image on NGC 4631: 1.
XMM Newton view on NGC 4631: 2.
Hubble Space Telescope close-up on the center of NGC 4631: 3.
Intergalactic cold dust in NGC 4631: 4.
Dust arch in the halo of NGC 4631: 5.


clic for 80% size 1716 x 931 (348 kB)

Clic here for a cropped raw L image in 80% size (263 kB)



Technical Details
Optics

16" cassegrain in secondary focus at f/10

Mount MK-100 GEM
Camera SBIG STL-11000M at -20C, internal filter wheel, AO-L for L frames
Filters Astronomik LRGB
Date May 16-19, 2007.
Location Wildon/Austria
Sky Conditions mag 5.5 sky, FWHM 1.6-2" for L, temperature 10 C
Exposure L:R:G:B = 360:90:60:90 minutes (30-minute sub-exposures).
Processing Image aquisition in Maxim DL 4.56, Preprocessing in CCDStack; Fitsliberator; Curves, high pass filter, unsharp mask, color balance in Photoshop;