This is ngc 5907 the 'splinter' galaxy and through the eyepiece is does look a little like a bright sliver in the sky. It's quite bright and on first impressions looks a little like ngc 891. However, closer examination reveals a subtle difference - ngc 891 has a pronounced bulge whereas ngc 5907 is almost completely flat. The dark dust lanes are clearly evident in both galaxies.
What my image does not show is that ngc 5907 is surrounded by an incredibly faint tidal stream of stars orbiting the central galaxy. You can see it here :
http://apod.nasa.gov/apod/ap080619.htmlSo what causes some galaxies to have bulging cores and others to have tidal streams?
It seems the answer lies in the way 2 galaxies collide and interact. If a small galaxy is eaten by a larger one then you would expect that the resultant core to be more tightly held together and so a bulge will be produced. For 2 large galaxies colliding you might expect a more violent interaction and a lot more chaos. NGC 5907 looks to have settled down quite nicely and only the tidal stream gives a clue to a possible violent past. So no bulge, a tidal stream and a fairly sedate looking galaxy is quite unusual.
As we are in collision with the dwarf Sagittarius galaxy and are on course for a collision with the Andromeda Galaxy, might we not expect our galaxy to produce a tidal stream and maybe a flat core, too?
My image, taken on a pretty good night, 30 x 120 second exposures.
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