ASTRO: Arp 227 a shell galaxy

Arp 227, NGC 474 and maybe NGC 470. It is classed by Arp under
"Galaxies not classifiable as S(piral) or E(lliptical); concentric
rings". NGC 474 is a classic shell galaxy. These are usually the
result of a merger though there's no evidence of this in this case. All
stars in it have a common motion. Normally if there's a recent merger
there are two families of stellar motion evident in the galaxy. That
isn't the case here. It could be due to a close encounter with its
neighbor NGC470 or more distant neighbor NGC 467 in the lower right
corner. Note that NGC 467 also has a tidal tail. NGC 474 is 93
million light years away based on redshift, NGC 470 is 95 million light
years distant but NGC 467 has a redshift consistent with a distance of
235 million light years! If NGC 470 caused the distortions in 474 why
isn't it similarly distorted as its mass appears less it should be even
more torn up? If 467 is involved it must have been a high speed pass
due to its high radial velocity. If it wasn't how did it get torn up?
Nearby, mostly off the lower edge of my image is CGCG 385-068 which has
a similar red shift to that of NGC 467. It does appear to have a small
tidal arm coming off its upper left end. Did that distort NGC 467? The
near edge on vertical spiral two stars left of NGC 467 likely is a
member of the Arp 227 group at 88 million light years. So is the
redshift of NGC 467 very misleading? If right it is 2.5 times farther
away than the other major galaxies in the image yet doesn't appear that
distant based on its angular size. Right from 470 and a bit up, half
way to the edge is [WGB2006] 011712+03080_c a bright infra red galaxy
600 million light years away. Most of the rest of the galaxies in the
image have no red shift data available for them. Arp 227 is in the
constellation of Pisces just north of the border with Cetus.

Two blue quasars are at the bottom of NGC470 at the SE edge. Dim one is
magnitude 19.9 and 10.2 billion light years away. The brighter is
magnitude 18.2 and 9.5 billion light years away.

Arp's photo:
http://nedwww.ipac.caltech.edu/level...ig_arp227.jpeg

14" LX200R @ f/10, L=6x10' 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".

Very interesting and good questions. My impression is that ngc467 &
ngc474 are the actual pair here. ngc470 isn't involved aside from being
in the same field (imho). Particularly telling is the similar color of
467 & 474 as well as the similar degree of tidal disturbance between the
two. Check out Mischa Schirmer's deep negative he
http://www.astro.uni-bonn.de/~mischa...ngc474_neg.jpg

I would call this "two ellipticals passing in the night with a spiral
looking on."

Rick Johnson wrote:
Arp 227, NGC 474 and maybe NGC 470. It is classed by Arp under
"Galaxies not classifiable as S(piral) or E(lliptical); concentric
rings". NGC 474 is a classic shell galaxy. These are usually the
result of a merger though there's no evidence of this in this case. All
stars in it have a common motion. Normally if there's a recent merger
there are two families of stellar motion evident in the galaxy. That
isn't the case here. It could be due to a close encounter with its
neighbor NGC470 or more distant neighbor NGC 467 in the lower right
corner. Note that NGC 467 also has a tidal tail. NGC 474 is 93
million light years away based on redshift, NGC 470 is 95 million light
years distant but NGC 467 has a redshift consistent with a distance of
235 million light years! If NGC 470 caused the distortions in 474 why
isn't it similarly distorted as its mass appears less it should be even
more torn up? If 467 is involved it must have been a high speed pass
due to its high radial velocity. If it wasn't how did it get torn up?


14" LX200R @ f/10, L=6x10' RGB=2x10', STL-11000XM, Paramount ME

Rick

------------------------------------------------------------------------



--
Adriano
http://www.edmar-co.com/adriano/
34°14'11.7"N

I'd not noticed the arc over the NW end of 476. It's mostly out of my
frame. I do need to redo this one when it gets far enough from the sun
that I can put several hours into it using longer sub frames. Moving
everything to the east 5 to 10 minutes would help as well. I wasn't
even thinking of 467 when I framed the shot.

Rick

Adriano wrote:
Very interesting and good questions. My impression is that ngc467 &
ngc474 are the actual pair here. ngc470 isn't involved aside from being
in the same field (imho). Particularly telling is the similar color of
467 & 474 as well as the similar degree of tidal disturbance between the
two. Check out Mischa Schirmer's deep negative he
http://www.astro.uni-bonn.de/~mischa...ngc474_neg.jpg

I would call this "two ellipticals passing in the night with a spiral
looking on."

Rick Johnson wrote:
Arp 227, NGC 474 and maybe NGC 470. It is classed by Arp under
"Galaxies not classifiable as S(piral) or E(lliptical); concentric
rings". NGC 474 is a classic shell galaxy. These are usually the
result of a merger though there's no evidence of this in this case.
All stars in it have a common motion. Normally if there's a recent
merger there are two families of stellar motion evident in the
galaxy. That isn't the case here. It could be due to a close
encounter with its neighbor NGC470 or more distant neighbor NGC 467 in
the lower right corner. Note that NGC 467 also has a tidal tail.
NGC 474 is 93 million light years away based on redshift, NGC 470 is
95 million light years distant but NGC 467 has a redshift consistent
with a distance of 235 million light years! If NGC 470 caused the
distortions in 474 why isn't it similarly distorted as its mass
appears less it should be even more torn up? If 467 is involved it
must have been a high speed pass due to its high radial velocity. If
it wasn't how did it get torn up?


14" LX200R @ f/10, L=6x10' RGB=2x10', STL-11000XM, Paramount ME

Rick

------------------------------------------------------------------------

Very good image of this interesting galaxy.
My only version from 2002 can not quite keep up with this ;-)
http://www.slilge.de/Binenwal/index_...60gut.jpg.html

Stefan


"Rick Johnson" schrieb im Newsbeitrag
ter.com...
Arp 227, NGC 474 and maybe NGC 470. It is classed by Arp under
"Galaxies not classifiable as S(piral) or E(lliptical); concentric
rings". NGC 474 is a classic shell galaxy. These are usually the
result of a merger though there's no evidence of this in this case. All
stars in it have a common motion. Normally if there's a recent merger
there are two families of stellar motion evident in the galaxy. That
isn't the case here. It could be due to a close encounter with its
neighbor NGC470 or more distant neighbor NGC 467 in the lower right
corner. Note that NGC 467 also has a tidal tail. NGC 474 is 93
million light years away based on redshift, NGC 470 is 95 million light
years distant but NGC 467 has a redshift consistent with a distance of
235 million light years! If NGC 470 caused the distortions in 474 why
isn't it similarly distorted as its mass appears less it should be even
more torn up? If 467 is involved it must have been a high speed pass
due to its high radial velocity. If it wasn't how did it get torn up?
Nearby, mostly off the lower edge of my image is CGCG 385-068 which has
a similar red shift to that of NGC 467. It does appear to have a small
tidal arm coming off its upper left end. Did that distort NGC 467? The
near edge on vertical spiral two stars left of NGC 467 likely is a
member of the Arp 227 group at 88 million light years. So is the
redshift of NGC 467 very misleading? If right it is 2.5 times farther
away than the other major galaxies in the image yet doesn't appear that
distant based on its angular size. Right from 470 and a bit up, half
way to the edge is [WGB2006] 011712+03080_c a bright infra red galaxy
600 million light years away. Most of the rest of the galaxies in the
image have no red shift data available for them. Arp 227 is in the
constellation of Pisces just north of the border with Cetus.

Two blue quasars are at the bottom of NGC470 at the SE edge. Dim one is
magnitude 19.9 and 10.2 billion light years away. The brighter is
magnitude 18.2 and 9.5 billion light years away.

Arp's photo:
http://nedwww.ipac.caltech.edu/level...ig_arp227.jpeg

14" LX200R @ f/10, L=6x10' 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".