ASTRO: Arp 64

Arp 64/UGC 9503 consists of three of the four galaxies that make up UGC
9503. They are located in Bootes about 434 million light-years away.
Arp put them under his classification of spirals with small high surface
brightness companion on the arms. In this case one companion for each
arm. Or as Arp put it "Both arms lead toward companions." At least
that's how it looked to Arp.

Redshift data indicates the primary galaxy, PGC 052698, is about 430
million light-years away. But there is no redshift data for either
companion. The western companion is SDSS J144522.63+192758.3. The one
to the northeast is LEDA 214322. As mentioned neither have a redshift
measurement that I could find. Without this measurement it is hard to
prove either are true companions. The latter isn't actually on an arm.
The arm does make a short jog in its direction but ends abruptly.
Certainly not fatal to it being a companion but doesn't prove it either.
In Arp's image this small galaxy does seem a bit distorted on the side
toward the arm. I don't see this however in either the SDSS or my
images. The other companion is seen virtually on the end of the other
arm. Again it doesn't prove anything but is suggestive.

This accounts for three of the 4 galaxies NED refers to as constituting
UGC 9503. Arp doesn't include the fourth in his image. It is the very
blue disk galaxy to the south southeast of Arp 64. It shows a small but
faint plume to its south and the disk is rather distorted.
Unfortunately it too has never had a redshift measurement taken. How
many of these 4 are truly related I have no idea. Apparently little
research has been done on this group.

To the southwest is the large elliptical like golden galaxy (near the
right edge of my enlarged and cropped image), ARK 458. This is a
catalog of emission line galaxies. It does have a redshift distance
that puts it at 439 million light-years. It is a member of the same
group as Arp 64. Being an emission line galaxy it is quite active. It
is also an IR galaxy. These two pieces of information are suggestive
that it may have had an encounter in the past to trigger such activity.
Though this isn't necessary. So could it be the cause of Arp 64's
drawn out arms rather than the two companions? It shows no hint of any
distortion however. Sorry, I have lots of questions but no answers.

Toward the lower right corner is an obvious galaxy cluster with two
major galaxy. The one on the right, SDSS J144433.71+192121.5 has a
spectroscopic redshift measurement putting it at 2.3 billion light years
away. The one on the right, SDSS J144431.76+192127.4 marks the center
of the cluster, MaxBCG J221.13237+19.35762. The galaxy has no redshift
data but the cluster has a photographic redshift distance of 2.5 billion
light years. Since a photographic redshift isn't as accurate as a
spectroscopic redshift I assume the 2.3 billion light years of the other
major member is likely more correct. It is listed as having 26 members
but no size is given. This appears to also be the galaxy cluster Abell
1960 though this has a different center as shown on the annotated image.
Abell 1960 is described as having a diameter of 16 arm minutes and a
distance of 2.3 billion light years, same as one of the galaxies above.

Arp's image
http://ned.ipac.caltech.edu/level5/A...big_arp64.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".

Got in too much of a hurry and attached an image twice. Here's the
correct cropped and enlarged image