ASTRO: Arp 336 Polar Ring Galaxy

Arp 336, NGC 2685, is an example of a polar ring galaxy though that's
hard to tell from its classification as (R)SB0+ pec. To me this is
Arp's wildest and most spectacular galaxy. It is probably the result of
the merger of two spiral galaxies that were oriented at right angles to
each other. Seeing wasn't up to what I'd have liked so this one needs
to be retaken next year. It is getting too far west (in my Polaris
tree) for another try this year. This is a very nearby object, being
only about 45 million light years away. It is sometimes called the
Helix Galaxy as the remains of one of the spiral galaxies seems to coil
around the other galaxy. Where the helix structure passes in front of
the other galaxy it is seen as a dark feature but where it is away from
the other galaxy it is an bright feature. It is also known as NGC 2685
and is classed by Arp under his "Miscellaneous" category. This is for
those few he cataloged that were one of a kind. At least as far as the
200" Palomar telescope can see. There is another famous polar ring
galaxy but it is too far south so wasn't on the survey plates Arp used
to make his catalog. Hubble took a famous image of it but I can't find
one of Arp 336. I find that surprising. A photo from Kitt Peak is at:
http://www.noao.edu/image_gallery/html/im0851.html

One note in NED says:
"NGC 2685 is perhaps the most unusual galaxy in the Shapley-Ames
catalogue. There are two axes of symmetry for the projected image; most
galaxies have only one. The central, amorphous spindle resembles a
normal S01 seen on edge. However, helical filaments surround the
spindle. Because of projection effects, it is impossible to tell whether
these filaments form complete circles around the spindle or whether they
start somewhere on the spindle and spiral outward at right angles to its
axis. The filaments are seen in absorption when they pass in front of
the bright background, but they are luminous when they are not
silhouetted. Note how the entire north-east end of the spindle is
covered with the projected absorption lanes of the helix. A luminous
external ring around the entire structure may be either a true ring or a
complete shell seen in projection. Many questions are unanswered about
this galaxy. Is the central feature a spheroid (with two axes equal as
in a plate or pancake), or is it an ellipsoid like a cigar? What is the
direction of the angular momentum vector? Is the external ring attached
to the central regions, or is it separate?"

The blue blob of a galaxy off the bottom left of Arp 336 is SDSS
J085530.07+584117.3. The spiral near the bottom is MCG +10-13-035. I
find no red shift data on either nor any other galaxies in my image.
Arp 336 is located in Ursa Major under the bear's chin.

Arp's photo with the 200" scope is at:
http://nedwww.ipac.caltech.edu/level...ig_arp336.jpeg

My image suffered greatly from deteriorating conditions. The green
frame was especially bad as seeing was 5.8" FWHM while blue was 2.3" and
Red 4". Two lum frames suffered from the camera mounting screws that
hold it parallel to the image plane had come loose in the wildly varying
winter temperatures. Weather kept conspiring against me until it was
too far west to try any more this year. Sorry about the elongated stars
and odd green problems (from the huge stars in the green frames). They
are beyond my current processing abilities. I worked for two weeks and
have helped it a lot but after three days of only making things worse I
give up an will go with this. I'll try again next year. It didn't help
that this was taken during the period the camera had come slightly
loose. Some frames were more tilted than others causing stars to
elongate on the east and west sides but at least the center was pretty
well in alignment.

14" LX200R @ f/10, L=4x10' RGB=2x10', 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".