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Old July 26th 09, 10:56 AM posted to alt.binaries.pictures.astro
Stefan Lilge
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Default ASTRO: Arp 104 "Rawhide Galaxies?"

Rick, great detail in this pair, a real treat.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Keenan's System NGC 5216 (south, bottom) and NGC 5218 north. Classed by
Arp under "Elliptical and elliptical-like Galaxies: Connected to Spirals"

One note says: "Distorted spiral with an S0 companion, well separated
but with a connecting arm. North (spiral) is NGC 5218, which has no
bright nucleus.

To me though these are the "Rawhide Galaxies." For some reason every
time I look at the image the Rawhide theme song jumps into my head. And
I rarely watched the show. The lines:
"Don't try to understand 'em,
Just rope and throw and grab 'em,
Soon we'll be living high and wide." seem to fit this pair.

There's confusion about which galaxy is which. Here's the NGC Project
on this issue: "NGC 5216 and NGC 5218. The MCG identifications are
reversed from those by all other observers. There is no apparent reason
for this in the NGC itself, and I doubt that Vorontsov or his colleagues
consulted JH's 1833 catalogue where there is an identification error.
For the record, Sir John makes his h 1635 a "nova" while he incorrectly
labels h 1636 as H II 841. Sir William's original observation was of
two objects which became H II 841 and H II 842. Sir John got the
identifications sorted out for the GC, and the NGC has them exactly
correct, too."

So, the MCG is the only catalogue which reverses the identifications.
All the other modern catalogues are correct in placing N5216
south-preceding N5218.
- Dr. Harold G. Corwin, Jr."

NED puts pair at 153 million light-years but puts NGC 5216 at only 140
million light years and classed as E0 pec, and 5218 at 139 million light
years classed as SBb pec and as a LINER galaxy as well. The interaction
may have triggered the activity needed to create a LINER status for the
galaxy.

The lower galaxy NGC 5216 reminds me of Arp 165 (
http://www.spacebanter.com/attachmen...tid=2474&stc=1 )
which was an elliptical galaxy with a faint blue arm but no sign of any
galaxy it had interacted with. NGC 5216 is very similar but this time
we know the culprit. It didn't fare very well in this near collision
either.

The galaxy east of NGC 5216 is SDSS J133257.25+624038.6 an IR galaxy 1.3
billion light-years

The galaxy NE of 5216 AT 3.7 billion light-years IS MAG 20.8 another,
east of NGC 5218 at 3.6 billion light-years is blue with the same
magnitude but appears fainter.

Above that galaxy listed at 3.6 billion light-years is a very blue star.
It is listed as a white dwarf. Usually one this blue has a planetary
nebula around it. This one obviously doesn't. In any case it is one
super hot but tiny star!

MaxBCG J202.88728+62.64181 BCG at 2.63 billion light-years is the anchor
galaxy of the galaxy cluster of the same name (without BCG at the end).
it consists of some 28 members many of which show in my image as
orange dots around this galaxy to the lower right of the NGC 5216. The
color contrast with the quasar below it is very strong.

There is a pair of nearly overlapping galaxies in upper right corner.
They are SDSS J133039.33+625507.1 at 2.7 billion light-years and SDSS
J133038.56+625508.8 with no red shift data so it is marked with a "?".
Thus I don't know if they are interacting or not.

The Q? above NGC 5218 denotes a possible QSO candidate per NED. Though
its status is rather indeterminate. It is classed as SDSS
J133038.56+625508.8, a quasar candidate; a galaxy in the Sloan Digital
Sky Survey and Galex; and an ultraviolet orbiting observatory classes it
as GALEX 2685493392111045227 an ultra violet excess source which isn't
surprising considering its blue color. The US Naval Observatory has it
classed as VisS which just means it is an unknown object visible in
ordinary light. I found no distant estimate for it.

In the upper left corner is a somewhat blue double galaxy. At least it
has two condensations. Oddly I can find no cataloged object at its
location. In fact there's nothing of its brightness cataloged within
several minutes of arc of this location. Yet the area is covered by the
SDSS. I checked the POSS II plates and it is a real object. How the
pros let this one get away I don't know.

Arp's image is at:
http://nedwww.ipac.caltech.edu/level...ig_arp104.jpeg

It is located in Ursa Major above the Big Dipper's handle right at the
boundary with Draco not far from Thuban.

14" LX200R @ f/10, L=9x10' RGB=5x10', STL-11000XM, Paramount ME

You'll notice I put in more than twice my normal time on this one. The
extra time really helps with faint ones like this pair.

Rick

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