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ASTRO: Arp 58 or "Who cut off my arm?"



 
 
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  #1  
Old April 4th 09, 11:11 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: Arp 58 or "Who cut off my arm?"

Arp 58, UGC 4457 is a bit over a half billion light years away in the
constellation of Cancer, not far from M44, the beehive cluster. I tried
taking this at 0.5" per pixel but seeing wasn't really up to it so I
reduced the image to 0.75" per pixel. Still higher than my normal image
scale. Arp classifies this one as a spiral with a small, high surface
brightness companion same as Arp 52. His notes say; "...companion on
end of broken arm nearly star-like". I'd have to agree. Actually there
may be two galaxies on the arm and the arm appears detached from the
galaxy to me. The obvious galaxy on the lower arm segment is LEDA
023937 an E0 elliptical galaxy that appears nearly starlike. What's
really odd is that it is blue in color. Ellipticals aren't supposed to
be blue as they are usually said to lack the dust and gas needed for new
star formation. I could find no explanation for its blue color except
one paper saying it's not a galaxy at all (see below). Unlike the also
blue companion of Arp 52 which was also blue this one does have a
classification and distance. The distance is the same as UGC 4457 so we
know it is a true companion. Complicating things is another galaxy,
SDSS J03201.11+291311.9. This is the blue blob just left and slightly
up from the blue E0 galaxy. To me it looks like just the end of the
mostly detached spiral arm but it is classed as a separate galaxy, not
as part of a galaxy like I'd expect. I also found it referred to as a
separate galaxy one reference. It has no classification.

More interesting to me is the very weird blue galaxy toward the upper
right corner of my image. It is SDSS J083129.83+191455.2 but I can find
no distance or classification data for it. It appears as two very
different objects, a compact blue galaxy and a fuzzy arc above it. I
find only one designation for it in the Sloan Digital Sky Survey
however. Nor can I find any paper on it. Seems worthy of one or two,
at least in my image. Did it too encounter Arp 58? Sure looks
distorted and blue like it recently encountered something and that's
about all there is in the area.

Back on Arp 58 one paper insists that the arms couldn't have been the
result of tidal interaction. Apparently saying these are HII regions
not separate galaxies at all. No one else seems to agree but it does
explain a blue elliptical "galaxy". If that paper is right then that
takes me back to that other strange galaxy in the upper right corner as
being involved. Where's that Ph.D. candidate looking for a thesis when
you want one?

Arp's Palomar 200" telescope image of the galaxies is at:
http://nedwww.ipac.caltech.edu/level...big_arp58.jpeg

14" LX 200R @ f/10, L=7x10' binned 1x1 RGB=2x10' binned 2x2,
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".

Attached Thumbnails
Click image for larger version

Name:	ARP58UGC04457L7X10X1RGB2X10-75.jpg
Views:	582
Size:	114.6 KB
ID:	2376  
  #2  
Old April 5th 09, 10:20 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: Arp 58 or "Who cut off my arm?"


The more I look at SDSS J083129.83+191455.2 in the upper right the more
I think it likely has interacted with Arp 58. It looks like a "sloshed"
galaxy. I've attached an image of NGC 5474 I did several years ago and
in dire need of reprocessing. It was "sloshed" when it passed by M101.
Turn it over and move it out to the distance of Arp 58 and it would be
a twin of SDSS J083129.83+191455.2.

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".

Attached Thumbnails
Click image for larger version

Name:	NGC5474L6X10RGB2X10R.jpg
Views:	167
Size:	324.1 KB
ID:	2378  
  #3  
Old April 7th 09, 09:45 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: Arp 58 or "Who cut off my arm?"

Great image Rick It would be nice to be able to "rewind" the scene and see
what really has happened.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 58, UGC 4457 is a bit over a half billion light years away in the
constellation of Cancer, not far from M44, the beehive cluster. I tried
taking this at 0.5" per pixel but seeing wasn't really up to it so I
reduced the image to 0.75" per pixel. Still higher than my normal image
scale. Arp classifies this one as a spiral with a small, high surface
brightness companion same as Arp 52. His notes say; "...companion on
end of broken arm nearly star-like". I'd have to agree. Actually there
may be two galaxies on the arm and the arm appears detached from the
galaxy to me. The obvious galaxy on the lower arm segment is LEDA
023937 an E0 elliptical galaxy that appears nearly starlike. What's
really odd is that it is blue in color. Ellipticals aren't supposed to
be blue as they are usually said to lack the dust and gas needed for new
star formation. I could find no explanation for its blue color except
one paper saying it's not a galaxy at all (see below). Unlike the also
blue companion of Arp 52 which was also blue this one does have a
classification and distance. The distance is the same as UGC 4457 so we
know it is a true companion. Complicating things is another galaxy,
SDSS J03201.11+291311.9. This is the blue blob just left and slightly
up from the blue E0 galaxy. To me it looks like just the end of the
mostly detached spiral arm but it is classed as a separate galaxy, not
as part of a galaxy like I'd expect. I also found it referred to as a
separate galaxy one reference. It has no classification.

More interesting to me is the very weird blue galaxy toward the upper
right corner of my image. It is SDSS J083129.83+191455.2 but I can find
no distance or classification data for it. It appears as two very
different objects, a compact blue galaxy and a fuzzy arc above it. I
find only one designation for it in the Sloan Digital Sky Survey
however. Nor can I find any paper on it. Seems worthy of one or two,
at least in my image. Did it too encounter Arp 58? Sure looks
distorted and blue like it recently encountered something and that's
about all there is in the area.

Back on Arp 58 one paper insists that the arms couldn't have been the
result of tidal interaction. Apparently saying these are HII regions
not separate galaxies at all. No one else seems to agree but it does
explain a blue elliptical "galaxy". If that paper is right then that
takes me back to that other strange galaxy in the upper right corner as
being involved. Where's that Ph.D. candidate looking for a thesis when
you want one?

Arp's Palomar 200" telescope image of the galaxies is at:
http://nedwww.ipac.caltech.edu/level...big_arp58.jpeg

14" LX 200R @ f/10, L=7x10' binned 1x1 RGB=2x10' binned 2x2,
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".



  #4  
Old April 7th 09, 09:45 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: Arp 58 or "Who cut off my arm?"

Great image Rick It would be nice to be able to "rewind" the scene and see
what really has happened.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 58, UGC 4457 is a bit over a half billion light years away in the
constellation of Cancer, not far from M44, the beehive cluster. I tried
taking this at 0.5" per pixel but seeing wasn't really up to it so I
reduced the image to 0.75" per pixel. Still higher than my normal image
scale. Arp classifies this one as a spiral with a small, high surface
brightness companion same as Arp 52. His notes say; "...companion on
end of broken arm nearly star-like". I'd have to agree. Actually there
may be two galaxies on the arm and the arm appears detached from the
galaxy to me. The obvious galaxy on the lower arm segment is LEDA
023937 an E0 elliptical galaxy that appears nearly starlike. What's
really odd is that it is blue in color. Ellipticals aren't supposed to
be blue as they are usually said to lack the dust and gas needed for new
star formation. I could find no explanation for its blue color except
one paper saying it's not a galaxy at all (see below). Unlike the also
blue companion of Arp 52 which was also blue this one does have a
classification and distance. The distance is the same as UGC 4457 so we
know it is a true companion. Complicating things is another galaxy,
SDSS J03201.11+291311.9. This is the blue blob just left and slightly
up from the blue E0 galaxy. To me it looks like just the end of the
mostly detached spiral arm but it is classed as a separate galaxy, not
as part of a galaxy like I'd expect. I also found it referred to as a
separate galaxy one reference. It has no classification.

More interesting to me is the very weird blue galaxy toward the upper
right corner of my image. It is SDSS J083129.83+191455.2 but I can find
no distance or classification data for it. It appears as two very
different objects, a compact blue galaxy and a fuzzy arc above it. I
find only one designation for it in the Sloan Digital Sky Survey
however. Nor can I find any paper on it. Seems worthy of one or two,
at least in my image. Did it too encounter Arp 58? Sure looks
distorted and blue like it recently encountered something and that's
about all there is in the area.

Back on Arp 58 one paper insists that the arms couldn't have been the
result of tidal interaction. Apparently saying these are HII regions
not separate galaxies at all. No one else seems to agree but it does
explain a blue elliptical "galaxy". If that paper is right then that
takes me back to that other strange galaxy in the upper right corner as
being involved. Where's that Ph.D. candidate looking for a thesis when
you want one?

Arp's Palomar 200" telescope image of the galaxies is at:
http://nedwww.ipac.caltech.edu/level...big_arp58.jpeg

14" LX 200R @ f/10, L=7x10' binned 1x1 RGB=2x10' binned 2x2,
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".



 




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