ASTRO: NGC 2146 A highly disturbed nearby galaxy.

NGC 2146 is a very strange galaxy in Camelopardalis. It's distance by
red shift is 40 million light-years. This is often unreliable this
close to us. Other methods at NED put it as close as 56 million
light-years by the Tully-Fisher method and as far as 90 million
light-years by the Sosies method. Splitting the difference gives 73
million light-years. The HST press release on this galaxy says 70
million light-years. A nice round value. How it was determined I don't
know.

The mystery is why this galaxy looks as it does. A merger would be the
most reasonable idea. For the arms to still be so disturbed most think
some remains of the other galaxy should exist but that doesn't seem to
be the case. This leaves interaction but there's no obvious candidate
for that. NGC 2146A in the upper left corner may be a neighbor but it
is much smaller. It looks rather normal. Being smaller it would have
taken the brunt of any interaction so is pretty well ruled out. No
other galaxies seem to be candidates. I searched out 5 degrees in all
directions and nothing with a significant mass turned up that could have
done the deed. All were tiny by comparison and looked unharmed but for
NGC 2336 which is a nice undistorted spiral that's on my to-do list.
Even without a candidate the HST page seems to go for the latter
explanation. But until someone finds the interacting galaxy I'm
favoring the idea it totally consumed the other galaxy tearing it to so
many shreds nothing recognizable is left but some plumes. I'd think
there'd be a compositional difference however between stars from each
galaxy and they'd be still in streams so recognizable. Especially if
one of the plumes is from the other galaxy. So far I didn't find any
papers noting this. A point in favor of the interacting faction I
admit. Sill where is it?

You can read more and see the HST image at:
http://www.spacetelescope.org/images/potw1134a/ Note their image is
false color. Still it shows many of the HII regions I picked up without
use of an H alpha filter. They are an orange-brown color in the false
color HST image rather than the pink color they are in my close to true
color image. Only two other galaxies in the image had any redshift data
as did one quasar. The pole region isn't covered by the Sloan survey so
only brighter galaxies, mostly IR luminous are cataloged. What few of
those were I've also noted by name in the annotated image but, of
course, without any distance estimate. Several interesting looking
galaxies didn't make any catalog NED carries and are noted with just a
question mark. On the other hand The Sky shows a galaxy PGC 142974
above NGC 2146 at 6h 18m 54s +78d 27' 8" at magnitude 18.6. There's
absolutely nothing at that position. That's not all that far from one
of the question mark galaxies but I can't corrupt its coordinates 6h 19m
51.7" +78d 27m 38" to match. Time to head for that booze cabinet again.

Clouds hampered this image. I probably should have retaken it. Instead
I threw out 5 of 8 L image lost to clouds but kept the other three even
though 2 were dimmed by clouds. Since I was taking 8 L I took 3 of each
color instead of my normal 2. Good thing as clouds nailed them to some
extent as well but I didn't throw any out. Instead I combined all color
and the three L images into a pseudo luminance image and used that.
Still color balance was pretty poor as the clouds did a number on all
color channels. I hope I managed to get them about right.

14" LX200R @ f/10, Pseudo L=12x10', RGB=3x10', STL-11000XM, Paramount ME

Rick
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