M108 - Spiral Galaxy

M108 is a tiny spiral galaxy by astronomical standards, only about one twentieth the mass of M31. Although we see the galaxy nearly edge on, the central bulge is all but absent. Whatever shines in the nuclear region is masked by turbulent eddies of dark matter lining the galaxy's highly fore-shortened arms. The nucleus might have also depleted itself long ago, or it has only periodic bursts of energetic activity that keeps it going. Brilliant regions of star formation among the obscuring matter look like signal flares burning in a storm. Visible in binoculars as a faint gray streak only two moon diameters (1°) northwest of the Owl Nebula (M97), or just 1° southeast of Merak (Beta Ursae Majoris), M108 is an interesting spiral. With its highly wrinkled texture, this 10th- magnitude system looks as if it is the shed skin of M82 - a galaxy with a similar demeanor - left here to dry. Even at 23X in a 4-inch, M108's elongated (8'.7) and highly mottled disk can be recognized. Moderate and high powers are needed to show its haphazard array of dark lanes, superposed stars, and irregularly bright nebulous patches, which look like they have been pasted together by a three-year-old. At 130 X one prominent, kinked, dark channel runs along the galaxy's northern rim. More difficult is a long dust lane that follows the southern edge of the galaxy. A beautiful, though delicate, fan of material sprays westward from a faint knot embedded in the western half of M108, and a misty breath of galactic haze shines feebly beneath a 13th magnitude star in the eastern half. A fainter glow connects that dim patch to the pseudo-nucleus- a fairly bright foreground star near the galaxy's invisible heart. The real challenge is to see the 14th- magnitude bead immediately southwest of that central pip.

Telescope:	TMB 152 F8 APO refractor
Focal Length:	1200 mm
Mount:	Takahashi NJP 160
Camera	Starlight XPress MX916
Guider:	SBIG STV
Exposures:	8 15-minute exposures
Location:	Cicero, IN
Software:	AstroArt