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ASTRO: Arp 138 No plumes but rather neat anyway



 
 
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  #1  
Old March 6th 11, 06:49 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
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Posts: 3,085
Default ASTRO: Arp 138 No plumes but rather neat anyway

Arp 138, NGC 4015, is a pair of galaxies in Coma Berenices about 210
million light-years away. It is right on the border with Leo. In fact
the right 25% of my image is in Leo. Arp put this pair in his category
Elliptical and elliptical like galaxies: Material emanating from
elliptical galaxies. His comment reads: "Absorption leads directly into
E galaxy." I presume this refers to the dark cloud off the end of the
spiral galaxy's tip. It's hard to tell if it is coming from the spiral
or the elliptical. Arp apparently considers it coming from the
elliptical or appearing to at least by the category it put it in. Since
the elliptical shows no other signs of dust and spirals are often very
dusty I'd suspect the spiral as being the more likely source of the
dust. The redshifts of the galaxies are virtually the same so no help
there.

Other than the dust cloud I see no sign the two galaxies are even
interacting. If they are it must be just beginning. Apparently they
aren't quite as close as they appear to be. NED classes them as S? and
E with no further refinement. It appears the spiral is closer to us
than the elliptical though its redshift is very slightly larger. Are
they on a collision course? No way to know as there's no way to measure
their proper motion across the field. They may be moving sideways far
faster than their approach velocity.

The field has several NGC galaxies in it. I've identified those on the
annotated image as well as redshift distances in billions of light-years
when known. There are distant galaxy clusters. Their position is
marked by the large cD galaxy at the heart of the cluster. They are
shown as having 18 or so members but I don't begin to see that many
around either cD galaxy. They are marked C/GC followed by their
distance in billions of light-years. NGC 4005 is also NGC 4007. Such
double names are surprisingly common in the NGC catalog.

There are two asteroids in the image. The bright one is (43477) 2001
BX7 at 18.7 magnitude. The fainter at my estimated magnitude of about
19.8 is -- I did it again -- unknown. Found and let another one get
away. This was taken March 20, 2010 so a bit late to try and find it
again. Minor planet center doesn't have it in their data base is all I
know.

Arp's image
http://nedwww.ipac.caltech.edu/level...ig_arp138.jpeg

Sloan image
http://astronomerica.awardspace.com/SDSS-30/NGC4015.php

14" LX200R @ f/10, L=4x10' 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".

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  #2  
Old March 16th 11, 09:38 PM posted to alt.binaries.pictures.astro
Stefan Lilge
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Posts: 2,269
Default ASTRO: Arp 138 No plumes but rather neat anyway

Rick,

I would bet on the spiral to be the source of the dust. Anyway, the dust
looks neat indeed covering the elliptical.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Arp 138, NGC 4015, is a pair of galaxies in Coma Berenices about 210
million light-years away. It is right on the border with Leo. In fact
the right 25% of my image is in Leo. Arp put this pair in his category
Elliptical and elliptical like galaxies: Material emanating from
elliptical galaxies. His comment reads: "Absorption leads directly into
E galaxy." I presume this refers to the dark cloud off the end of the
spiral galaxy's tip. It's hard to tell if it is coming from the spiral
or the elliptical. Arp apparently considers it coming from the
elliptical or appearing to at least by the category it put it in. Since
the elliptical shows no other signs of dust and spirals are often very
dusty I'd suspect the spiral as being the more likely source of the
dust. The redshifts of the galaxies are virtually the same so no help
there.

Other than the dust cloud I see no sign the two galaxies are even
interacting. If they are it must be just beginning. Apparently they
aren't quite as close as they appear to be. NED classes them as S? and
E with no further refinement. It appears the spiral is closer to us
than the elliptical though its redshift is very slightly larger. Are
they on a collision course? No way to know as there's no way to measure
their proper motion across the field. They may be moving sideways far
faster than their approach velocity.

The field has several NGC galaxies in it. I've identified those on the
annotated image as well as redshift distances in billions of light-years
when known. There are distant galaxy clusters. Their position is
marked by the large cD galaxy at the heart of the cluster. They are
shown as having 18 or so members but I don't begin to see that many
around either cD galaxy. They are marked C/GC followed by their
distance in billions of light-years. NGC 4005 is also NGC 4007. Such
double names are surprisingly common in the NGC catalog.

There are two asteroids in the image. The bright one is (43477) 2001
BX7 at 18.7 magnitude. The fainter at my estimated magnitude of about
19.8 is -- I did it again -- unknown. Found and let another one get
away. This was taken March 20, 2010 so a bit late to try and find it
again. Minor planet center doesn't have it in their data base is all I
know.

Arp's image
http://nedwww.ipac.caltech.edu/level...ig_arp138.jpeg

Sloan image
http://astronomerica.awardspace.com/SDSS-30/NGC4015.php

14" LX200R @ f/10, L=4x10' 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".




 




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