ASTRO: Arp 257

Arp 257 is a double galaxy in Hydra about 170 million light years
distant. Arp classed it in his category, Galaxies (not classifiable as
E or S): Irregular clumps. for once I can sort of agree on the not
classifiable as E or S part. I'm not sure what the clumps are he speaks
of. Likely it is the two blue blobs leading from the lower galaxy to
the upper. Arp's comment reads; "Galaxies joined by segment of thin arc."

Both galaxies are cataloged as UGC 4638. But they do carry separate
entries in the MGC catalog. The southern being MGC +00-23-005 which is
described as a disrupted spiral (?) with chaotic outer disk, main body
0.8' x 0.5'. NED classes it as S pec. The upper galaxy is MGC
+00-23-006. NED says of its classification "spiral ?"

The blue color of both would indicate spiral or irregular and certainly
indicates massive star formation is currently going on in both due to
their tidal interaction. SIMBAD considers the larger of the two other
galaxies to be "Part of Galaxy" and gives it the designation VV 041c.
VV 041a and b are the two galaxies Arp considered as Arp 257. Is it
part of the upper or lower galaxy? Looks rather like a separate galaxy
to me. What about the fourth galaxy? Wish I knew. Neither NED nor
SIMBAD mention it. The blue galaxy north of the Arp 257 group near a
bright star is anonymous. To the west of Arp 257 nearly 9.5' is 6dF
J0851002-022201 and is only half the distance of Arp 257 at about 85
million light years. There are no other galaxies with a distance
estimate that I could find. This region is rather obscured by our
galaxy's dust. For that reason it has been little studied. Sloan stays
away from such regions so hasn't covered it nor is it likely to in a
future survey.

I didn't check around my field of view. I wish I had as just out of the
image at the top is UGC 04640 a much larger galaxy than those of Arp 257
but at the same distance. In fact the red shift is virtually identical
so it is likely related. I usually check for such things before taking
the image but didn't this time -- the one time I should have.

Arp's image:
http://nedwww.ipac.caltech.edu/level...ig_arp257.jpeg

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".

Wow, that's quite a mess. Looks like more than two galaxies to me but they
may just have been ripped apart.
You are lucky to have such interesting objects to process, I have about a
dozen of unprocessed nights, but nothing really good or interesting. Maybe I
can motivate myself to work on something this weekend...

Stefan

"Rick Johnson" schrieb im Newsbeitrag
. com...
Arp 257 is a double galaxy in Hydra about 170 million light years
distant. Arp classed it in his category, Galaxies (not classifiable as
E or S): Irregular clumps. for once I can sort of agree on the not
classifiable as E or S part. I'm not sure what the clumps are he speaks
of. Likely it is the two blue blobs leading from the lower galaxy to
the upper. Arp's comment reads; "Galaxies joined by segment of thin arc."

Both galaxies are cataloged as UGC 4638. But they do carry separate
entries in the MGC catalog. The southern being MGC +00-23-005 which is
described as a disrupted spiral (?) with chaotic outer disk, main body
0.8' x 0.5'. NED classes it as S pec. The upper galaxy is MGC
+00-23-006. NED says of its classification "spiral ?"

The blue color of both would indicate spiral or irregular and certainly
indicates massive star formation is currently going on in both due to
their tidal interaction. SIMBAD considers the larger of the two other
galaxies to be "Part of Galaxy" and gives it the designation VV 041c.
VV 041a and b are the two galaxies Arp considered as Arp 257. Is it
part of the upper or lower galaxy? Looks rather like a separate galaxy
to me. What about the fourth galaxy? Wish I knew. Neither NED nor
SIMBAD mention it. The blue galaxy north of the Arp 257 group near a
bright star is anonymous. To the west of Arp 257 nearly 9.5' is 6dF
J0851002-022201 and is only half the distance of Arp 257 at about 85
million light years. There are no other galaxies with a distance
estimate that I could find. This region is rather obscured by our
galaxy's dust. For that reason it has been little studied. Sloan stays
away from such regions so hasn't covered it nor is it likely to in a
future survey.

I didn't check around my field of view. I wish I had as just out of the
image at the top is UGC 04640 a much larger galaxy than those of Arp 257
but at the same distance. In fact the red shift is virtually identical
so it is likely related. I usually check for such things before taking
the image but didn't this time -- the one time I should have.

Arp's image:
http://nedwww.ipac.caltech.edu/level...ig_arp257.jpeg

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".