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ASTRO: Arp 201
Arp 201/UGC 224 is a pair of galaxies located about 824 to 830 million
light years distant (depending on which redshift you use) and is located
in the constellation of Pisces near its border with Cetus. The pair are
usually considered as interacting. Arp's note reads: "VV connection
between galaxies not seen here or on Survey prints." I can't see a
connection on my image either. However a 1986 note at NED reads:
"Interacting pair of E (south) and S0 (north) galaxies. Faint matter is
ejected northward from the latter." Is it this "faint matter" that
caught Arp's eye? He has it classed under galaxies with matter ejected
from nuclei. The note's authors consider these stars, dust and gas as
being ejected by some force from the northern galaxy. More likely it is
some sort of tidal plume and could have come from either galaxy. It is
quite a bit bluer than either galaxy. That would indicate that mostly
dust and gas was pulled from one of the galaxies and has formed into new
stars since the plume was created.
Kanipe and Webb see the three patches of light that come out of the
southern galaxy's southeast side and go south as the ejected material.
These are clearly background galaxies. Though in Arp's image they are
just faint smudges. Same in mine though I only pick up the two brighter
ones with a hint of the fainter one closest to the southern galaxy. I
suppose it is possible this is what Arp referred to but without more to
go on I vote for the northern galaxy's blue plume. I've included a DR8
release image of this object. Note the two brighter background galaxies
in Kanipe's and Webb's opinion that are the ejected material are quite
different colors with the northern reddish while the southern is
slightly blue. Neither were strong enough for me to get sufficient
color data so they appear white in my image. NED identifies the two
brightest as SDSS J002338.56-003049.9 (north) and SDSS
J002338.71-003059.7 (south). The faint northernmost object isn't listed
in NED at all though one not seen in Arp's image but faintly visible in
the SDSS image is. Therefore I think it a faint foreground star. It
appears starlike in both the Arp and the SDSS images.
None of this means Arp didn't think these objects were ejected from the
southern galaxy. He held, and still holds I believe, that quasars are
ejected from active galaxies. So he could see these two galaxies and a
star as objects ejected from the galaxy. In any case the blue plume
from the northern galaxy is what makes this one interesting to me.
While the note indicates the southern galaxy is an elliptical and the
northern S0, NED abstains from classifying them at all. To me I'd say
the notes classifications appear reasonable.
As mentioned, Arp considered quasars as being emitted from active
galaxies. Several going out to nearly 11 billion light-years are in the
image as well as some Ultraviolet Excess objects that are likely
quasars. Unfortunately for Arp's theory their red shifts are wrong.
His weird idea is that what ever it is a galaxy ejects that we call a
quasar, it's redshift increases with time. Thus, if it is close to the
galaxy it was released recently and has a low red shift while those
further out have higher red shifts. Since we can't see in 3D how we are
to determine which are close to it I don't know. The example Kanipe and
Webb gives seems to rely on simple 2D angular distance which makes no
sense to me. Maybe I'm missing something. In any case using 2D
distances the the redshifts appear rather random in this image. Many
more are just off the edges of my image in all directions. They too
have a similar random spread of redshift values.
Several galaxy clusters are found in the image. The one marked GC 3.0
is an estimated 3 billion light years distant and has some 40 galaxies
within a radius of 2.15 minutes of arc. The label is placed at the
center coordinate. In the past with an annotated image I labeled
galaxies with a G, quasars with a Q etc. Recently I've received
complaints that they couldn't find what a "G 0.35" was in any catalog.
For this one if it is a galaxy only the distance in billions of light
years is noted. Some objects NED lists both as a quasar and an
Ultraviolet Excess Source (UvES). In some cases it lists the quasar
designation first and other UvES first. I assume this is due to
positional differences of a fraction of a second of arc rather than a
preference. I think it safe to consider them quasars, even those only
listed as UvES. In any case if both were used I show both in the order
NED listed them.
The annotated image shows only two galaxies closer than the Arp 201
group. I say group since two other galaxies in the image are at a
similar redshift distance so it is likely that all 4 are related. Other
than these 6 galaxies, everything else NED had a redshift value for, are
over a billion light years distant (other than the 4 asteroids of
course). Oddly, all 4 asteroids are bunched in the lower left quadrant.
After I wrote the above Jeff Kanipe sent me an image from the VV catalog
that appears to show a connection between the two galaxies and is likely
the cause for Arp's comment. Comparing the image to the POSS 1 plates
it appears if you enhance greatly certain pixels in that digitized image
you get exactly the same "connection". To do this you have to not
similarly enhance other pixels of these values over the image. I tried
taking many deep images in H alpha, blue and red light, far deeper than
the POSS 1 plates and failed to see even a hint of this connection. I
enhanced them every which way but no such connection appeared. I think
the VV image is due to overactive processing of grain in the POSS 1
plates. I've attached the VV image Jeff sent me so you can do your own
comparison. Note the connection is brighter in this image than the
plume both Arp and I imaged. It does, if real, indicate this plume
comes from the southern galaxy. But why the SDSS, Arp nor I or any
other image I found show this "brighter" feature? Could it be
polarized? That I couldn't test. I have no information on the
particulars of the VV image.
14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME
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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