ASTRO: Arp 185

Arp 185 is in Arp's class for galaxies with narrow filaments. Though I
don't see any in this case. Arp's comment doesn't help much. It read:
""Condensed nucleus, faint outer arms less curved than inner arms."
Kanipe and Webb seem to indicate he may be referring to the brighter
segments of these faint outer arms. They are about the only part of the
outer arms visible in Arp's image.

Arp 185 is located in Ursa Minor just above the bowl of the little
dipper and is about 60 million light-years away. Red shift says 61
which may be rather accurate in this case, at least the HST folks give
this figure. This was the first image taken with the ACS camera after
the last repair mission got it back in working order. The image is at:
http://apod.nasa.gov/apod/ap091228.html. The field doesn't include the
faint outer arms however.

It is classed by NED as (R)SB(rs)bc;HIISy2. The R and (rs) would
indicate a ring structure. The SBbc means a barred spiral with arms
intermediate between those of b and c structure (a is tightly wound
while d is wide open arms. HII means lots of HII emission which is
obvious in the Hubble image. Only the large region at the south end of
the bar shows as pink in my image though other show as blue due to the
HII being overpowered by the new super hot blue stars created by these
regions. It also has an active nucleus of the Sy2 class. This is
because it is considered a starburst galaxy by many of the papers I
looked at.

It has a rather broken bar with arm segments coming off not just at the
ends. One arm seems to come right off the core on the east side.
Several arm segments come off the west side, one at the core and two
below the core. North of the core it's pretty much a jumbled mess on
the west side. I saw nothing in the papers about any ideas how it got
this odd structure. Could a merger be involved? I have no idea. Seems
possible. I'd expect that to show in a detailed velocity analysis of
the galaxy. Apparently that's not been done as best I could tell. Did
anything come of the HST image? Again I drew a blank. The Hubble site
only talks about how it shows the ACS camera is again operational.

Near the left edge of the image is the strange spiral galaxy UGC 10509.
It's arm structure is very weird. Is this really two interacting
galaxies on top of one another? I don't really see a core of a second
galaxy. Did it interact with either or both of the nearby galaxies to
the north? Only one has redshift data. That indicates it is likely at
least part of the same local group. Neither seem distorted however.
Being much smaller I'd expect they'd suffer far more in an interaction.
For now I'll say they likely aren't interacting but something
certainly has it would seem. Unfortunately, Hubble didn't test the ACS
camera on it.

Only a very few other galaxies are even cataloged in this field.
Coverage up by the pole seems rather poor for galaxies. What I did find
were several X-ray sources. All are very bright in visual light. Some
are very blue which isn't surprising for an X-ray object. The ones with
the RIXOS prefix were found by the ROSAT X-ray satellite's survey. All
of those are considered by NED to be X-ray galaxies with active galactic
nuclei. But not as quasars though they are so bright and so distant I
find that surprising. I'd think only a quasar would be that bright at
their distance. One is from the RX catalog. Also the result of the
ROSAT X-Ray satellite but apparently not from the survey? I am only
guessing as to the difference. These NED says were obtained not from a
published catalog but from "the literature". The one with that
designation in my image is listed by another X-ray catalog (Pietsch+Arp)
as being a quasar. It is more distant than all but one and by far the
brightest in apparent magnitude.

NED also lists 5 galaxy clusters from the OC05 and OC06 galaxy cluster
catalogs (Optical Cluster). Unfortunately the positions are listed with
an error circle of 25" of arc radius! Also no size or galaxy count is
given. Because of there being no way to pin down their location to a
sufficient degree and lack of any other data I didn't include them in
the annotated image For those interested enough to look them up they
a OC06 J1633+7808; OC05 J1632+7806; OC04 J1629+7811; OC04b J1629+7806
and OC04a J1629+7803.

Most galaxies in the image weren't cataloged any place I looked. Even
the rather bright blue fuzz ball south east of Arp 185. I marked it
with a question mark. I really am interested in what the heck it is.
Most galaxies of its shape are ellipticals that are very red. It
probably is an S0 galaxy seen end on. Usually they have a higher
surface brightness than this one does. It's a rare breed, whatever it is.

Arp's image:
http://ned.ipac.caltech.edu/level5/A...ig_arp185.jpeg

14" LX200R@ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Rick
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