ASTRO: Arp 241 Dancing Tadpoles

Arp 241/UGC 9425 is sometimes known as Segner's Wheel. Looks more like
spinning tadpoles to me. It is located in central Bootes at a distance
of about 475 million light-years. Arp classed it under "Appearance of
Fission." It's more a dance of death and rebirth as these two galaxies
swirl about each other and likely will merge in the future to become an
elliptical galaxy. The merger may have already happened but we won't
see it for several hundred million years. Arp saw it as appearing to be
the reverse, one galaxy that appears to be splitting into two. That
doesn't necessarily mean he thought this was what was happening. He
wanted to draw attention to unusual galaxies and the puzzles they
create. Such a description could serve this purpose. I just don't know.

According to Kanipe and Webb the name "Segner's Wheel" is probably named
for "...the 18th century Slovak scientist Janos Andras Segner,
considered the father of the water turbine. Segner also built
observatories at two of his academic posts." I'd never heard any of
this before.

A third galaxy at the same redshift is seen to the northwest of Arp 241.
It doesn't appear to have interacted with Arp 241.

The center of the 2 billion light-year galaxy cluster Abell 1944 is a
few minutes south of Arp 245. I've marked the center on the annotated
image. Most of the galaxies appear to the west of the center however.
At least I assume most of these faint galaxies are part of the cluster.
NED shows it as 10 minutes in diameter. To its northwest is another
Abell cluster, Abell 1941, with a diameter of 1.2 billion light-years
and a size of 14 minutes. I don't really see it but have also marked
its center as defined in NED. Then to make things even more interesting
there's the ZwCl 1435.5+3037 galaxy cluster toward the southwest end of
the chain of galaxies of Abell 1944. It is said to be 17 minutes in
diameter and contain some 180 members. It is shown as Distance Class
VD. That stands for Very Distant, Extremely Distant is the only class
more distant but I can't translate this into redshift or a time travel
distance. It likely is much the same cluster but with a larger cut off
radius as Abell 1944. Anyone know for sure?

Just to add to the galaxy cluster confusion further to the southwest we
come to the galaxy cluster MaxBCG J219.37724+30.37448 which is shown
centered on a galaxy of the same name which is noted at NED as being a
bright cluster galaxy. The cluster has an estimated distance of 2
billion light-years, no given diameter and a member count of 19. So how
does this fit the others? My head hurts. But it gets worse. Just off
the bottom of my image almost directly below Abell 1944 is Abell 1943
which is 12 minutes in diameter and thus extends into the southern part
of the image. There's no distance for it other than the note it is
distance class 6. This puts its members in the 17.3 to 18 magnitude
range for tenth brightest cluster member. Since it is richness class 2
-- 80 to 129 members I'm not sure how that helps much other than the
most distant class is 7 for all below 18th magnitude. How this
translates to distance is beyond me. On average I suppose fainter is
more distant. Is that true of the 10th brightest member? Now I really
have a headache.

Migraine time! In the upper right corner is the galaxy and galaxy
cluster MaxBCG J219.17017+30.59602. The anchor galaxy is quite large
but has no redshift measurement that I could find. Estimate for the
cluster is 1.5 billion light-years but all around it are galaxies of 1.3
billion light-years by redshift. Are these members? The cluster is
described in NED as having 15 members, no size is given. Several more
galaxy clusters are to be found around the edges of this image that
likely extend into it but enough is enough. I've used up my pain killer
supply just getting this far.

I do find it surprising there were no quasars in the image considering
how deep it goes. One was just off the image to the south but NED
listed none within the image. But at there are a couple very distant
galaxies at 4 and 4.2 billion light-years in the frame.

One blue frame was severely hurt by haze or something. I used it anyway
but maybe I shouldn't have. It seems to have hurt color more than
helping. I didn't go back and try with only the good blue frame or
retake it.

Arp's image
http://ned.ipac.caltech.edu/level5/A...ig_arp241.jpeg

14" LX200R @ f/10, L=5x10' 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".

"Rick Johnson" wrote in message
ster.com...

Arp 241/UGC 9425

*******************
Very nice, Rick. I will be imaging at the club observatory this Friday, and
might take a stab it it. Thanks.

George