ASTRO: 2 Arp Galaxies (trying yet again)

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Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

On 6/5/2011 2:47 AM, Rick Johnson wrote:

Posting the text only never made it to my or archive servers at
Spacebanter.com. But the image alone did. Trying again with the text
which I'm breaking into two parts to see if something in one is the key.

Rick

Another Arp pairing

Arp 328/Hickson 72/UGC 09532. This is a chain of galaxies located in
Bootes. All but one of the galaxies are about 600 million light-years
distant, the other nearly twice as distant and thus not a member. Before
going further and looking only at the full or cropped image, see if you
can determine which is the odd galaxy out. It may not be the one you
think. Arp put this group his class for galaxy chains and had this
comment: "6 galaxies more or less in line; center one has semi-stellar
companion." There are 7 in the chain including the sneaky interloper.
Hickson also includes only 6 but one he includes is the "fraud". NED
shows 7 galaxies for Arp 328 while Arp himself limits it to 6 as does
Hickson. Both leave out the most southern. Yet one note at NED reads:
"With respect to the original Hickson list we have included the
amorphous object g which clearly interacts with galaxy c. This is the
one I've marked as VV164g. G is blue and does seem to have a bulge
toward c but I'm not sure this is sufficient for it to be clearly
interacting. This brings us to the "semi-stellar companion" I assume
he is speaking of D. While in my image it may appear to have two cores
of about the same brightness the SDSS image clearly shows the southern
one to be a star. There is a slight brightening north of the core, best
seen in the Sloan image but it isn't semi-stellar. Nor can I see much
of anything in the burned out core of Arp's image as it is on the website.

Below and left of component g is yet another compact golden elliptical
like galaxy, SDSS J144759.73+190202.0 at 18th magnitude. No one
considers it part of the group. Nor is any redshift data available for
it. There are several small galaxies about component A as well. Are
they satellites of A or distant line of sight galaxies? Probably the
latter though a note at NED considers this possible.

A is classed as S0, B as S0?, C as E2, D as SB0, E as Scd, F as S0 and g
as S0?.

--
Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".

On 6/5/2011 2:47 AM, Rick Johnson wrote:

Part two of the text.

Arp 47/MCG +03-38-014 is classed by Arp under Spirals with low surface
brightness companions on arms. I suppose that refers to the little
galaxy off the north arm that curves back sharply. That galaxy is 20th
magnitude SDSS J144715.24+185134.8. No redshift is given so it's
unknown if it is truly a companion. There is the very obvious galaxy to
the west of MCG +03-38-014. It is 16.6 magnitude NPM1G +19.0402. NED
and other catalogs consider these two a pair. In fact NED lists these
to under Arp 47. Seems way too bright to be the companion on the arm
Arp refers to. So which is it? I still think it the one that
definitely appears to be on the arm and certainly is faint.
Unfortunately NPM1G +19.0402 doesn't have a redshift value either which
doesn't help us any. NED makes no attempt to classify this obvious
spiral or either "companion".

Arp's image is one of his poorest. This isn't Arp's normal work. Makes
me wonder if some night assistant took this data rather than Arp
himself. He may have had quirky ideas bordering on crackpot in later
years but his telescope work was very precise. One possibility is Arp
did, like I did, and took both of these with one image. This would have
pushed the Winn Corrector to its limits and maybe beyond. Arp 48 may
have been right at the edge of the image where the Winn Corrector
couldn't quite handle the prime focus distortions. The stars radiate
away from the position of Arp 328 like it was centered and this one just
too far away for full correction. The elongation of the star in the
lower right corner seems greater which fits this idea. I can't see Arp
guiding this poorly.

There's no redshift data on anything in the field other than these two
objects. NED lists several thousand galaxies in my field but except for
these two Arp's there's nothing on it. Note however that both are at
the same approximate redshift distance and thus quite likely part of the
same group.

This is my last May, 2010 object and due to bright June skies that limit
me to part of an object a night I only captured 4 last June. I have a
chance to get back to less than a 12 month backlog.

Arp's image of 328
http://ned.ipac.caltech.edu/level5/A...ig_arp328.jpeg

Arp's image of 47
http://ned.ipac.caltech.edu/level5/A...big_arp47.jpeg

14" LX200R @ f/10, L=8x10' RGB=2x10'x3, 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".