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ASTRO: Arp 298 -- interacting galaxies



 
 
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  #1  
Old April 4th 10, 04:16 AM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: Arp 298 -- interacting galaxies

Arp 298 is a pair of interacting galaxies about 200 million light-years
distant in the constellation of Pegasus just northwest of the circlet of
Pisces. The northern galaxy is IC 5283. It shows a nice tidal plume
off to the west northwest. Unfortunately, due to a major blunder by an
imager who will remain nameless this image was taken like they do it in
the movies -- with the lights on in the observatory. I don't mean the
red 10 watt ones but three 60 watt white bulbs! This increased my noise
level greatly and cut my limiting magnitude from the common 22.5 to 23
by about 1.5 magnitudes. Actually I thought this image lost when I
realized what I'd done but its amazing what GradientXTermanator can do!

My image also seems to show a faint plume to the north from IC 5283
coming off the eastern end. Unfortunately, it may be just noise due to
the lights being left on. Though I do see hints of it in the Hubble
image when seen at lowest resolution. IC 5283 is classed as SA(r)cd
pec? by most sources I checked. A few say it may be a Seyfert 1 galaxy.
It certainly is a mixed up galaxy. If it has a core it is shifted
"sloshed?" to the eastern end and highly distorted by its encounter with
its companion. So I found it rather surprising when one source claimed
they are not interacting galaxies. I stopped reading at that point.
Probably shouldn't have. Maybe it was a misprint.

There is definitely a spray of stars between IC 5283 and its larger
companion NGC 7469. NGC7469 is classed as (R')SAB(rs)a. While I found
few papers on IC 5283, everyone and their uncle have apparently written
something on NGC 7469. A search turned up an endless stream of
references! It seems it is a prototypical Seyfert 1 galaxy so has been
studied every which way -- though the field is out of the Sloan survey
area so they haven't covered it. It's core is surrounded by a ring of
massive star formation that appears rather continuous in my image except
for a few brighter areas. That's an illusion due to low resolution.
Hubble shows it to be made up of dozens of bright star forming regions.
From this ring there's an apparent outer ring. It is really two
spiral arms that overlap making what appears to be continuous ring.
Even my lower resolution shows the ends of the arms. One paper said the
star forming knots were more common on the northern side that faces IC
5283 and were a good indicator of the interaction between the two. I
agree the interaction likely helped form these regions but to say that
is why more are on that side just doesn't fly to my way of thinking.
Galaxies rotate. Even a "new" region like these have likely made one or
more trips around the galaxy in this time. This would make it mostly
coincidence that we happened to catch things where more were on that
side of the galaxy. Differential rotation would quickly destroy any
organized pattern. It's likely these have been interacting at least a
half billion years to create the plume and spray of stars we do see,
plenty of time for star forming regions of NGC 7469 to be randomized.
The inner ring certainly shows a rather even distribution of star
forming regions.

Arp classed this pair under double galaxies with the comment:
"Absorption, knot. Note apparent re-entrant spiral arm on southern
galaxy." I'm not sure what he sees as the "re-entrant spiral arm." The
more I look at Arp's photo as well as the Hubble image I am wondering if
IC 5283, the northern one, might not be two interacting spirals itself.
I didn't find any hint of this possibility in the literature however.

There are two asteroids in my image or should be according to the minor
planet center. The brighter is (105526) 2000 RQ26 at magnitude 18.0. It
is easily seen as a short slightly downward slanting streak NE of the
bright star that's NE of Arp 298. The other is listed at magnitude 19.5
and should be visible but I show nothing in that location. It could be
it was lost in the gradient from the observatory lights. The data for
its orbit is a bit skimpy based only on a 34 day arc. Also, it was
discovered in 2004 yet hasn't made one orbital rotation since discovery
so may be far fainter than the predicted magnitude. I usually can go at
least a magnitude fainter than this in the FITS image so this is a bit
of a mystery. It is 2004 JR45 for those wanting to try and find it.

In preparing the annotated image I came across CXOMP J230252.1+085520 an
X-ray object discovered by the Chandra X-Ray Observatory Multiwavelength
Project. It is classed by NED as a Seyfert 1 galaxy. The kicker is
that they put its distance at just over 12 billion light years at
magnitude 21.3. Quasar maybe, galaxy that size that early in our
universe's existence? That's one heck of a Seyfert AGN! I have trouble
swallowing that. But it isn't the only one like this in the image. At
magnitude 21.2 is another Seyfert 1 galaxy found by Chandra that is
listed at 9.1 billion light years, CXOMP J230252.2+084810. Note these
are the magnitude in red light rather than green I normally use. My CCD
is rather insensitive in red light. There are several others including
some found by ROSAT. All are marked as Seyfert 1 galaxies with red
shifts that seem far beyond anything I should be able to image if they
are galaxies rather than quasars. All are marked on the annotated image
with G? to denote my uncertainty. To complicate things further one
ROSAT object, not pinned down by Chandra, has rather vague coordinates
with a large error bar for position. In that case I've put a question
mark after the distance to indicate this is my best guess as to the
object based on magnitude and location in relation to the error circle.

While the field hasn't been covered by Sloan a surprising number of
objects did have red shift data. NED lists 5 galaxy clusters in the
image. One had a galaxy at the exact position listed. I've shown that
one on the annotated image with a GC label. I couldn't really see any
sign of the others so haven't marked them.

I can't explain the lack of identified objects on the eastern half of
the image. Might be I hit the very edge of the surveys. Other than
that I'm out of ideas.

Hubble's great image:
http://hubblesite.org/gallery/album/entire/pr2008016bz/
http://hubblesite.org/newscenter/arc...8/16/image/bz/

Arp's image
http://nedwww.ipac.caltech.edu/level...ig_arp298.jpeg

14" LX200R @ f/10, L=4x10' RGB=1x20'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".

Attached Thumbnails
Click image for larger version

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Size:	233.1 KB
ID:	2879  Click image for larger version

Name:	ARP298L4X10rgb1x20x3-ID.jpg
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Views:	293
Size:	89.7 KB
ID:	2881  
  #2  
Old April 10th 10, 11:04 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: Arp 298 -- interacting galaxies

Rick,

as usual it is a joy for me to watch the interesting objects you manage to
dig out.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
. com...
Arp 298 is a pair of interacting galaxies about 200 million light-years
distant in the constellation of Pegasus just northwest of the circlet of
Pisces. The northern galaxy is IC 5283. It shows a nice tidal plume
off to the west northwest. Unfortunately, due to a major blunder by an
imager who will remain nameless this image was taken like they do it in
the movies -- with the lights on in the observatory. I don't mean the
red 10 watt ones but three 60 watt white bulbs! This increased my noise
level greatly and cut my limiting magnitude from the common 22.5 to 23
by about 1.5 magnitudes. Actually I thought this image lost when I
realized what I'd done but its amazing what GradientXTermanator can do!

My image also seems to show a faint plume to the north from IC 5283
coming off the eastern end. Unfortunately, it may be just noise due to
the lights being left on. Though I do see hints of it in the Hubble
image when seen at lowest resolution. IC 5283 is classed as SA(r)cd
pec? by most sources I checked. A few say it may be a Seyfert 1 galaxy.
It certainly is a mixed up galaxy. If it has a core it is shifted
"sloshed?" to the eastern end and highly distorted by its encounter with
its companion. So I found it rather surprising when one source claimed
they are not interacting galaxies. I stopped reading at that point.
Probably shouldn't have. Maybe it was a misprint.

There is definitely a spray of stars between IC 5283 and its larger
companion NGC 7469. NGC7469 is classed as (R')SAB(rs)a. While I found
few papers on IC 5283, everyone and their uncle have apparently written
something on NGC 7469. A search turned up an endless stream of
references! It seems it is a prototypical Seyfert 1 galaxy so has been
studied every which way -- though the field is out of the Sloan survey
area so they haven't covered it. It's core is surrounded by a ring of
massive star formation that appears rather continuous in my image except
for a few brighter areas. That's an illusion due to low resolution.
Hubble shows it to be made up of dozens of bright star forming regions.
From this ring there's an apparent outer ring. It is really two
spiral arms that overlap making what appears to be continuous ring.
Even my lower resolution shows the ends of the arms. One paper said the
star forming knots were more common on the northern side that faces IC
5283 and were a good indicator of the interaction between the two. I
agree the interaction likely helped form these regions but to say that
is why more are on that side just doesn't fly to my way of thinking.
Galaxies rotate. Even a "new" region like these have likely made one or
more trips around the galaxy in this time. This would make it mostly
coincidence that we happened to catch things where more were on that
side of the galaxy. Differential rotation would quickly destroy any
organized pattern. It's likely these have been interacting at least a
half billion years to create the plume and spray of stars we do see,
plenty of time for star forming regions of NGC 7469 to be randomized.
The inner ring certainly shows a rather even distribution of star
forming regions.

Arp classed this pair under double galaxies with the comment:
"Absorption, knot. Note apparent re-entrant spiral arm on southern
galaxy." I'm not sure what he sees as the "re-entrant spiral arm." The
more I look at Arp's photo as well as the Hubble image I am wondering if
IC 5283, the northern one, might not be two interacting spirals itself.
I didn't find any hint of this possibility in the literature however.

There are two asteroids in my image or should be according to the minor
planet center. The brighter is (105526) 2000 RQ26 at magnitude 18.0. It
is easily seen as a short slightly downward slanting streak NE of the
bright star that's NE of Arp 298. The other is listed at magnitude 19.5
and should be visible but I show nothing in that location. It could be
it was lost in the gradient from the observatory lights. The data for
its orbit is a bit skimpy based only on a 34 day arc. Also, it was
discovered in 2004 yet hasn't made one orbital rotation since discovery
so may be far fainter than the predicted magnitude. I usually can go at
least a magnitude fainter than this in the FITS image so this is a bit
of a mystery. It is 2004 JR45 for those wanting to try and find it.

In preparing the annotated image I came across CXOMP J230252.1+085520 an
X-ray object discovered by the Chandra X-Ray Observatory Multiwavelength
Project. It is classed by NED as a Seyfert 1 galaxy. The kicker is
that they put its distance at just over 12 billion light years at
magnitude 21.3. Quasar maybe, galaxy that size that early in our
universe's existence? That's one heck of a Seyfert AGN! I have trouble
swallowing that. But it isn't the only one like this in the image. At
magnitude 21.2 is another Seyfert 1 galaxy found by Chandra that is
listed at 9.1 billion light years, CXOMP J230252.2+084810. Note these
are the magnitude in red light rather than green I normally use. My CCD
is rather insensitive in red light. There are several others including
some found by ROSAT. All are marked as Seyfert 1 galaxies with red
shifts that seem far beyond anything I should be able to image if they
are galaxies rather than quasars. All are marked on the annotated image
with G? to denote my uncertainty. To complicate things further one
ROSAT object, not pinned down by Chandra, has rather vague coordinates
with a large error bar for position. In that case I've put a question
mark after the distance to indicate this is my best guess as to the
object based on magnitude and location in relation to the error circle.

While the field hasn't been covered by Sloan a surprising number of
objects did have red shift data. NED lists 5 galaxy clusters in the
image. One had a galaxy at the exact position listed. I've shown that
one on the annotated image with a GC label. I couldn't really see any
sign of the others so haven't marked them.

I can't explain the lack of identified objects on the eastern half of
the image. Might be I hit the very edge of the surveys. Other than
that I'm out of ideas.

Hubble's great image:
http://hubblesite.org/gallery/album/entire/pr2008016bz/
http://hubblesite.org/newscenter/arc...8/16/image/bz/

Arp's image
http://nedwww.ipac.caltech.edu/level...ig_arp298.jpeg

14" LX200R @ f/10, L=4x10' RGB=1x20'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".



  #3  
Old April 10th 10, 11:04 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: Arp 298 -- interacting galaxies

Rick,

as usual it is a joy for me to watch the interesting objects you manage to
dig out.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
. com...
Arp 298 is a pair of interacting galaxies about 200 million light-years
distant in the constellation of Pegasus just northwest of the circlet of
Pisces. The northern galaxy is IC 5283. It shows a nice tidal plume
off to the west northwest. Unfortunately, due to a major blunder by an
imager who will remain nameless this image was taken like they do it in
the movies -- with the lights on in the observatory. I don't mean the
red 10 watt ones but three 60 watt white bulbs! This increased my noise
level greatly and cut my limiting magnitude from the common 22.5 to 23
by about 1.5 magnitudes. Actually I thought this image lost when I
realized what I'd done but its amazing what GradientXTermanator can do!

My image also seems to show a faint plume to the north from IC 5283
coming off the eastern end. Unfortunately, it may be just noise due to
the lights being left on. Though I do see hints of it in the Hubble
image when seen at lowest resolution. IC 5283 is classed as SA(r)cd
pec? by most sources I checked. A few say it may be a Seyfert 1 galaxy.
It certainly is a mixed up galaxy. If it has a core it is shifted
"sloshed?" to the eastern end and highly distorted by its encounter with
its companion. So I found it rather surprising when one source claimed
they are not interacting galaxies. I stopped reading at that point.
Probably shouldn't have. Maybe it was a misprint.

There is definitely a spray of stars between IC 5283 and its larger
companion NGC 7469. NGC7469 is classed as (R')SAB(rs)a. While I found
few papers on IC 5283, everyone and their uncle have apparently written
something on NGC 7469. A search turned up an endless stream of
references! It seems it is a prototypical Seyfert 1 galaxy so has been
studied every which way -- though the field is out of the Sloan survey
area so they haven't covered it. It's core is surrounded by a ring of
massive star formation that appears rather continuous in my image except
for a few brighter areas. That's an illusion due to low resolution.
Hubble shows it to be made up of dozens of bright star forming regions.
From this ring there's an apparent outer ring. It is really two
spiral arms that overlap making what appears to be continuous ring.
Even my lower resolution shows the ends of the arms. One paper said the
star forming knots were more common on the northern side that faces IC
5283 and were a good indicator of the interaction between the two. I
agree the interaction likely helped form these regions but to say that
is why more are on that side just doesn't fly to my way of thinking.
Galaxies rotate. Even a "new" region like these have likely made one or
more trips around the galaxy in this time. This would make it mostly
coincidence that we happened to catch things where more were on that
side of the galaxy. Differential rotation would quickly destroy any
organized pattern. It's likely these have been interacting at least a
half billion years to create the plume and spray of stars we do see,
plenty of time for star forming regions of NGC 7469 to be randomized.
The inner ring certainly shows a rather even distribution of star
forming regions.

Arp classed this pair under double galaxies with the comment:
"Absorption, knot. Note apparent re-entrant spiral arm on southern
galaxy." I'm not sure what he sees as the "re-entrant spiral arm." The
more I look at Arp's photo as well as the Hubble image I am wondering if
IC 5283, the northern one, might not be two interacting spirals itself.
I didn't find any hint of this possibility in the literature however.

There are two asteroids in my image or should be according to the minor
planet center. The brighter is (105526) 2000 RQ26 at magnitude 18.0. It
is easily seen as a short slightly downward slanting streak NE of the
bright star that's NE of Arp 298. The other is listed at magnitude 19.5
and should be visible but I show nothing in that location. It could be
it was lost in the gradient from the observatory lights. The data for
its orbit is a bit skimpy based only on a 34 day arc. Also, it was
discovered in 2004 yet hasn't made one orbital rotation since discovery
so may be far fainter than the predicted magnitude. I usually can go at
least a magnitude fainter than this in the FITS image so this is a bit
of a mystery. It is 2004 JR45 for those wanting to try and find it.

In preparing the annotated image I came across CXOMP J230252.1+085520 an
X-ray object discovered by the Chandra X-Ray Observatory Multiwavelength
Project. It is classed by NED as a Seyfert 1 galaxy. The kicker is
that they put its distance at just over 12 billion light years at
magnitude 21.3. Quasar maybe, galaxy that size that early in our
universe's existence? That's one heck of a Seyfert AGN! I have trouble
swallowing that. But it isn't the only one like this in the image. At
magnitude 21.2 is another Seyfert 1 galaxy found by Chandra that is
listed at 9.1 billion light years, CXOMP J230252.2+084810. Note these
are the magnitude in red light rather than green I normally use. My CCD
is rather insensitive in red light. There are several others including
some found by ROSAT. All are marked as Seyfert 1 galaxies with red
shifts that seem far beyond anything I should be able to image if they
are galaxies rather than quasars. All are marked on the annotated image
with G? to denote my uncertainty. To complicate things further one
ROSAT object, not pinned down by Chandra, has rather vague coordinates
with a large error bar for position. In that case I've put a question
mark after the distance to indicate this is my best guess as to the
object based on magnitude and location in relation to the error circle.

While the field hasn't been covered by Sloan a surprising number of
objects did have red shift data. NED lists 5 galaxy clusters in the
image. One had a galaxy at the exact position listed. I've shown that
one on the annotated image with a GC label. I couldn't really see any
sign of the others so haven't marked them.

I can't explain the lack of identified objects on the eastern half of
the image. Might be I hit the very edge of the surveys. Other than
that I'm out of ideas.

Hubble's great image:
http://hubblesite.org/gallery/album/entire/pr2008016bz/
http://hubblesite.org/newscenter/arc...8/16/image/bz/

Arp's image
http://nedwww.ipac.caltech.edu/level...ig_arp298.jpeg

14" LX200R @ f/10, L=4x10' RGB=1x20'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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