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ASTRO: NGC 7013 A galaxy near the Veil



 
 
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Old September 17th 12, 09:12 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Default ASTRO: NGC 7013 A galaxy near the Veil

NGC 7013 is a rather nice spiral galaxy that is often overlooked since
it hides in plain sight but in a constellation not known for galaxies --
Cygnus the Swan. It is less than 2 degrees from the southeast edge of
the Veil Nebula complex in fact. This means it is rather heavily
obscured and its color balance severely altered. It is much redder in my
image than it really is. 60% brighter in red light than green and and
60% dimmer in blue light than green light. Twice as much of its blue
light is blocked than its red light giving it a rather red color. The
arms are likely far bluer than they appear in this image. The
extinction appears to vary quite a bit across the galaxy. At least my
attempts to correct for this extinction resulted in a very uneven color
effect. I could have forced the colors but decided to just go with what
hit the sensor as adjusted for its known light curves. Most of the
stars in the image are in front of the absorbing dust so are mostly correct.

Red shift puts the galaxy only about 22 million light-years distant.
The only Tully measurement of its distance puts it at 46 million
light-years. I suspect this is closer to correct but its error bar is
rather large.

NED and the NGC Project classes it as SA(r)0/a and notes its a LINER
galaxy so has an active core region. The (r) refers to the apparent
ring that forms its brightest region around the core. Outside the ring
the arms are faint, diffuse and mostly featureless. While I show a
rather interesting color pattern to this outer disk I suspect that is
due to differences in dust absorption by our galaxy rather than real.
Note I said apparent ring. While no official Hubble image exists of
this galaxy they did take a very few (2) mono images with WFPC2. I've
done a quick process of the 10 minute detection image. It shows the
ring is mostly due to poor resolution from ground based telescopes of
the extensive dust structure of the galaxy and is not real at all. I
tried many ways to bring out the ring and it just wouldn't happen. I
used the detection image which is a pretty much white light image so the
lack of the ring isn't due to some wavelength effect.

There is a nebula at the top of the image which is in the general
direction of the Veil complex. I can't find it listed in SIMBAD. As
the data came in I figured it was H alpha from some far flung piece of
the Veil or maybe of the large HII complex of central Cygnus not far
away. But its color suggests it is dim dust and thus possibly galactic
cirrus illuminated by the light of our galaxy rather than some
individual star as is the case with most reflection nebula. If anyone
knows more please let me know. Searching the net I've found a couple
others noting the nebula but also unable to pin it down.

While NED lists a handful of strong IR emitting background galaxies none
have any distance data and are mostly very faint I didn't prepare an
annotated image.

In processing this image the quite red (b-v=2.28!) star at the north end
of the galaxy was a pain to deal with. I failed rather miserably to do
so. While the HST image was framed to omit the star its glare is severe
in their images as well so I don't feel quite so bad failing to deal
with it like I wanted to.

14" LX200R @ f/10, L=4x10 RGB=2x10, STL-11000XM, Paramount ME

Rick
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Prefix is correct. Domain is arvig dot net

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