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ASTRO: Arp 284 Galaxies in collision



 
 
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  #1  
Old September 15th 08, 08:13 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Default ASTRO: Arp 284 Galaxies in collision

Arp 284 is a pair of interacting galaxies NGC 7715 and NGC 7714 left to
right. Arp classifies these under the heading of "infall and
attraction" whatever that means. They are located a bit over 100
million light years away in the constellation of Pisces. NGC 7714 is a
starburst galaxy. It has strong H alpha emission though I didn't take
it in that light so its not well seen in my shot. The starburst
occurred some 3 to 9 million years ago. Note the odd reddish tidal arm
at the lower right that just doesn't seem to fit the rest of the galaxy.
The companion NGC 7715 has no significant H alpha emission and is not
a starburst galaxy. It is classed as an irregular galaxy and is not an
edge on spiral as it might appear. 7714 is a SB spiral that has been
highly distorted by the interaction. Its core has emission lines that
classify it as a LINER galaxy, a type with a somewhat active black hole
in its nucleus.

The bright star at the upper right of the image is also very
interesting. It is SAO 128268 and is 126 light years away. What is
interesting is that it is moving very rapidly through the sky. I was
checking the POSS1 plates when I noticed it wasn't in the same place as
it is in my photo.
http://stdatu.stsci.edu/cgi-bin/dss_...fov=NONE&v3 =
Note the two stars on either side of it are above it in that photo yet
below it in my shot. It is moving upward and a bit to the east at a
rate of about 1/3rd of a second of arc per year. In the approximately
50 years between the photos, the motion is quite obvious.

The star just below Arp 284 is one of the very few in all my images that
is visible to the naked eye. 16 Psc shines at magnitude 5.7 It is a
spectroscopic double star about 100 light years away known as HD 221950
or 16 Psc. It's glare made processing this image very difficult.
Reading through some of the scientific papers on this pair many mention
their measurements have large error bars due to the star so they were
bothered by it as well.

A Kitt Peak photo of Arp 284 is at:
http://www.noao.edu/outreach/aop/observers/n7714.html
It is a mirror image for some reason. Also the star cloud in 7714 that
is very blue in my image is quite red in the Kitt Peak shot. The
difference is likely due to our handling of the blue glare of 16 Psc.
Since such star clouds are normally blue I'll go out on a very thin limb
and vote for mine being more correct Probably foolhardy as that is an
Adam Brock image.

One other object to find in this image is a very blue "star" that is to
the upper left of NGC 7715. It is about halfway between two orange
stars. As the quotes indicate this isn't a star at all. While NGC 7714
is a LINER galaxy, that is, one with a weakly active black hole at its
center the other end of this spectrum is the quasar. They are a black
hole at the center of a galaxy that's so active it gives off more light
than an entire galaxy of a trillion stars! That's what this blue
star-like object really is. It is the active black hole of a galaxy
over 9.8 BILLION light years, light travel time, away.

14" LX200R @ f/10, L=4x10' binned 2x2 RGB=2x10' binned 3x3, 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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  #2  
Old September 15th 08, 08:23 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: Arp 284 Galaxies in collision


Sorry for the double post. While sending it the power blinked taking
the router off line and cutting the internet connection. That triggered
a message saying the sending failed and did I want to try again. Since
the power was back (computer is on UPS, Router in another room isn't) I
sent it again only to find the first copy got through after all.

I should have checked before resending. I'll know next time.

Rick

  #3  
Old September 17th 08, 02:25 AM posted to alt.binaries.pictures.astro
John N. Gretchen III
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Default ASTRO: Arp 284 Galaxies in collision

Great image Rick!


John N. Gretchen III
http://www.tisd.net/~jng3
 




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