ASTRO: Arp 40 and more

Arp 40/IC 4271 is another from Arp's category for spiral galaxies with
low surface brightness companions on their arms. It is located in Canes
Venatici about 760 to 770 million light-years distant. I suppose the
southern member is the "companion" but to me they are of about equal
surface brightness, neither being all that faint. I certainly don't see
either as being on an arm of the other. To me it appears the southern
galaxy is in the foreground. It has a dusty disk larger than the
optical disk. It is easily seen against the more distant northern
galaxy as a dark band "separating" the two galaxies. It is seen in
Arp's and Sloan images as well.

Are they interacting? Hard to say. Both are Seyfert 2 galaxies. At
one time this was thought to be a pretty good sign that interaction was
going on. Though now it appears such classification doesn't necessarily
mean an interaction. Though with both being Seyfert 2 it might in this
case. Still I see no real sign of distortion to either (unless that
dust disk qualifies). Other than these two overlapping I really don't
see what Arp saw in this pair.

Far more interesting to me is a pair I had on my "Arp-like" list. I've
managed two, and sometimes more Arp galaxies in one image but this is
the first (and I think only) time I also have one from the Arp-like list
in the image. It is in the lower left corner and I didn't realize it
was in the shot at the time. If I had I'd have framed the shot better.
It is SDSS J132957.37+371744.8, a spiral galaxy at a distance of about
750 million light-years. It has a very weird structure. A wide arm
that appears to have been drawn out with no corresponding arm on the
other side. More interesting though is that from the bottom of the
galaxy a faint "arm" comes out of nowhere and appears to lead west and a
bit north to a faint galaxy, SDSS J132953.47+371750.6. Another galaxy
appears connected to it a few seconds of arc to the northwest. That one
is not listed in the Sloan survey or in NED. Is this a real connection?
I see hints of it in the Sloan image and it appears quite real in my
data. Note too how the big spiral seems to have a piece cut right off
its north side! Sloan survey lists the western side of the galaxy as a
separate entry, SDSS J132956.73+371747.9 with no distance noted. Could
it really be a separate galaxy? The odd arm seems to come from its
position, wind around and behind the main galaxy then come out the other
side as the wide arm, almost as if it were a huge plume of a
disintegrating galaxy. This could explain the cut off appearance. Or is
my mind wandering afield at 2 a.m.? The main galaxy is also in the
2MASS IR catalog as 2MASX J13295738+3717447. So is the galaxy directly
east, 2MASX J13300048+3717277 with a redshift distance of 760 million
light-years. Could all three of these plus the 2 Arp 40 galaxies all be
part of the same group? Probably. Just above the top of my image just
a hair left of center is the center of the Abell 1749 galaxy cluster
with a diameter of 40' of arc containing some 51 galaxies. Its distance
is listed as 770 million light-years.

The galaxy north of Arp 40 is 2MASX J13295621+3718226, distance unknown.
Toward the lower left corner is the galaxy pair (GP), NGP9
F270-0262533/PGC 2097470 at 1.9 billion light-years. This doesn't mean
they are interacting but they could be. At that distance my resolution
is insufficient to say either way.

These galaxies may be too far away to be photogenic but they sure are
interesting, just the same. My enlarged, cropped image includes both
galaxy systems at 0.67" per pixel. I've also included the Sloan images
of these galaxies.

Arp's under exposed image
http://nedwww.ipac.caltech.edu/level...big_arp40.jpeg

14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

A galaxy west of Arp 40 was labeled at 10 billion light years on the
annotated image. It should read 1.0 billion. Corrected image attached.

Rick
--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".