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ASTRO: NGC 7094 and a bonus nebula



 
 
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  #1  
Old October 8th 08, 08:43 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: NGC 7094 and a bonus nebula

Despite my return to galaxies last post I'm not done with planetary
nebula. NGC 7094 a planetary in Pegasus not far from the famous
globular cluster M15. The central star in this nebula is a rather odd
star. It is known as a hybrid PG 1159 star. What this means is that
it, first off, has an unusual amount of hydrogen left in its atmosphere.
Secondly it is a variable star. White dwarf stars are normally dead
stars only giving off heat and light stored in them when their nuclear
furnaces were still working. When they die they throw off the outer
atmosphere that still has hydrogen, creating the planetary nebula, and
retaining the core of heavier elements created by the nuclear furnace.
They get a small amount of energy from gravitational collapse as they
cool but they shouldn't very in brightness. But some do. It is thought
that the outer atmosphere of the star becomes more or less opaque
depending on the ionization level of certain heavy elements such as iron
in the atmosphere. It is this variation of ionization that makes the
star appear to vary in brightness. In fact it doesn't, its just that
the atmosphere blocks the light at time. Such cycles are very
irregular. In this case the star varies at a rate of 2000 to 5000
seconds. Since my exposure of this guy was 6000 seconds it may have
varied 3 times during my exposure! Thus catching this isn't easy, nor
would I try. I knew this before I took the image.

What I didn't know was that it shares the field with a very faint
nebulosity. This nebulosity isn't listed in any catalog I have, nor
does it appear to be galactic cirrus. Not expecting it I severely
underexposed for it, especially the color frames which are very noisy.
Don't consider the color of this faint nebulosity as at all correct, the
color is mostly noise. If anyone knows what it is please let me know.
I need to go back and try a much longer exposure. But something is
reflecting into my field. When I centered the nebula a rather bright
ghostly nebula appeared to the west of the nebula. I have no idea where
the reflection came from, M15? To get rid of it I had to lower the
object. Raising it didn't help. Since the nebula is mostly "below" the
planetary that means I lost some of it, though I didn't realize it at
the time. I can't find any reliable distance data for this planetary.
Again, if anyone knows let me know.

Conditions went from fair to bad during this exposure. The loss of
resolution caused the blue and especially green frames to be "defocused"
creating the odd blue-green halos around bright stars as well as making
them larger than usual. Yet another reason to redo this one but I have
such a backlog of objects not taken the first time it is hard to go back
and reimage those I should.

14" LX200R @ f/10, L=4x10', 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 October 8th 08, 09:22 PM posted to alt.binaries.pictures.astro
Stefan Lilge
external usenet poster
 
Posts: 2,269
Default ASTRO: NGC 7094 and a bonus nebula

Neat image Rick, very good detail. Another one to reshoot, to my surprise I
found that I have not imaged this nebula in the last few years.

Stefan

"Rick Johnson" schrieb im Newsbeitrag
ster.com...
Despite my return to galaxies last post I'm not done with planetary
nebula. NGC 7094 a planetary in Pegasus not far from the famous
globular cluster M15. The central star in this nebula is a rather odd
star. It is known as a hybrid PG 1159 star. What this means is that
it, first off, has an unusual amount of hydrogen left in its atmosphere.
Secondly it is a variable star. White dwarf stars are normally dead
stars only giving off heat and light stored in them when their nuclear
furnaces were still working. When they die they throw off the outer
atmosphere that still has hydrogen, creating the planetary nebula, and
retaining the core of heavier elements created by the nuclear furnace.
They get a small amount of energy from gravitational collapse as they
cool but they shouldn't very in brightness. But some do. It is thought
that the outer atmosphere of the star becomes more or less opaque
depending on the ionization level of certain heavy elements such as iron
in the atmosphere. It is this variation of ionization that makes the
star appear to vary in brightness. In fact it doesn't, its just that
the atmosphere blocks the light at time. Such cycles are very
irregular. In this case the star varies at a rate of 2000 to 5000
seconds. Since my exposure of this guy was 6000 seconds it may have
varied 3 times during my exposure! Thus catching this isn't easy, nor
would I try. I knew this before I took the image.

What I didn't know was that it shares the field with a very faint
nebulosity. This nebulosity isn't listed in any catalog I have, nor
does it appear to be galactic cirrus. Not expecting it I severely
underexposed for it, especially the color frames which are very noisy.
Don't consider the color of this faint nebulosity as at all correct, the
color is mostly noise. If anyone knows what it is please let me know.
I need to go back and try a much longer exposure. But something is
reflecting into my field. When I centered the nebula a rather bright
ghostly nebula appeared to the west of the nebula. I have no idea where
the reflection came from, M15? To get rid of it I had to lower the
object. Raising it didn't help. Since the nebula is mostly "below" the
planetary that means I lost some of it, though I didn't realize it at
the time. I can't find any reliable distance data for this planetary.
Again, if anyone knows let me know.

Conditions went from fair to bad during this exposure. The loss of
resolution caused the blue and especially green frames to be "defocused"
creating the odd blue-green halos around bright stars as well as making
them larger than usual. Yet another reason to redo this one but I have
such a backlog of objects not taken the first time it is hard to go back
and reimage those I should.

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



  #3  
Old October 9th 08, 07:16 AM posted to alt.binaries.pictures.astro
J McBride
external usenet poster
 
Posts: 274
Default ASTRO: NGC 7094 and a bonus nebula

Nice image Rick! That planetary is very blue. That extra nebula is not
surprising though. I saw an image on Astromart yesterday posted by Roland
Christen that showed intergalactic dust up to and around NGC 7331 and
Stephen's Quintet. I have also seen images of similar nebula around M81-m82
taken by Tom Davis with a 10ASA.

Joe


"Rick Johnson" wrote in message
ster.com...
Despite my return to galaxies last post I'm not done with planetary
nebula. NGC 7094 a planetary in Pegasus not far from the famous
globular cluster M15. The central star in this nebula is a rather odd
star. It is known as a hybrid PG 1159 star. What this means is that
it, first off, has an unusual amount of hydrogen left in its atmosphere.
Secondly it is a variable star. White dwarf stars are normally dead
stars only giving off heat and light stored in them when their nuclear
furnaces were still working. When they die they throw off the outer
atmosphere that still has hydrogen, creating the planetary nebula, and
retaining the core of heavier elements created by the nuclear furnace.
They get a small amount of energy from gravitational collapse as they
cool but they shouldn't very in brightness. But some do. It is thought
that the outer atmosphere of the star becomes more or less opaque
depending on the ionization level of certain heavy elements such as iron
in the atmosphere. It is this variation of ionization that makes the
star appear to vary in brightness. In fact it doesn't, its just that
the atmosphere blocks the light at time. Such cycles are very
irregular. In this case the star varies at a rate of 2000 to 5000
seconds. Since my exposure of this guy was 6000 seconds it may have
varied 3 times during my exposure! Thus catching this isn't easy, nor
would I try. I knew this before I took the image.

What I didn't know was that it shares the field with a very faint
nebulosity. This nebulosity isn't listed in any catalog I have, nor
does it appear to be galactic cirrus. Not expecting it I severely
underexposed for it, especially the color frames which are very noisy.
Don't consider the color of this faint nebulosity as at all correct, the
color is mostly noise. If anyone knows what it is please let me know.
I need to go back and try a much longer exposure. But something is
reflecting into my field. When I centered the nebula a rather bright
ghostly nebula appeared to the west of the nebula. I have no idea where
the reflection came from, M15? To get rid of it I had to lower the
object. Raising it didn't help. Since the nebula is mostly "below" the
planetary that means I lost some of it, though I didn't realize it at
the time. I can't find any reliable distance data for this planetary.
Again, if anyone knows let me know.

Conditions went from fair to bad during this exposure. The loss of
resolution caused the blue and especially green frames to be "defocused"
creating the odd blue-green halos around bright stars as well as making
them larger than usual. Yet another reason to redo this one but I have
such a backlog of objects not taken the first time it is hard to go back
and reimage those I should.

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



----------------------------------------------------------------------------
----





  #4  
Old October 9th 08, 07:08 PM posted to alt.binaries.pictures.astro
Rick Johnson[_2_]
external usenet poster
 
Posts: 3,085
Default ASTRO: NGC 7094 and a bonus nebula

Joe,
As I mentioned in the post, I don't think this is galactic cirrus as you
mention in connection with these other objects. The nebula in my shot
is strongest in red and virtually absent in blue. Cirrus would show
nearly equally in all three from the images of it I've seen. Also I've
taken these other objects at the same or longer exposure time and while
I can find the cirrus in them it is too weak to bring out. This is
several times stronger than any cirrus I know of. Nor does it have the
wispy dusty look of cirrus. This looks more like ERE emission from the
response in the RGB filters rather than reflective though some Halpha
may be involved as well. A shot with the H alpha filter would answer
the latter. Since it was so weak in blue H alpha can't be a major
player or I'd see H beta in the blue. Though it was getting lower in
the sky when I took the blue so it might be lost to blue extinction but
I wasn't that low per the headers. But ERE is very smooth, not clumpy
like this so I don't like that idea either. I was hoping someone might
already know of it. I see no hint of it in my M15 shot but that is also
a far shorter exposure using only 2 minute subs to prevent the core from
saturating.

Rick

J McBride wrote:

Nice image Rick! That planetary is very blue. That extra nebula is not
surprising though. I saw an image on Astromart yesterday posted by Roland
Christen that showed intergalactic dust up to and around NGC 7331 and
Stephen's Quintet. I have also seen images of similar nebula around M81-m82
taken by Tom Davis with a 10ASA.

Joe


"Rick Johnson" wrote in message
ster.com...

Despite my return to galaxies last post I'm not done with planetary
nebula. NGC 7094 a planetary in Pegasus not far from the famous
globular cluster M15. The central star in this nebula is a rather odd
star. It is known as a hybrid PG 1159 star. What this means is that
it, first off, has an unusual amount of hydrogen left in its atmosphere.
Secondly it is a variable star. White dwarf stars are normally dead
stars only giving off heat and light stored in them when their nuclear
furnaces were still working. When they die they throw off the outer
atmosphere that still has hydrogen, creating the planetary nebula, and
retaining the core of heavier elements created by the nuclear furnace.
They get a small amount of energy from gravitational collapse as they
cool but they shouldn't very in brightness. But some do. It is thought
that the outer atmosphere of the star becomes more or less opaque
depending on the ionization level of certain heavy elements such as iron
in the atmosphere. It is this variation of ionization that makes the
star appear to vary in brightness. In fact it doesn't, its just that
the atmosphere blocks the light at time. Such cycles are very
irregular. In this case the star varies at a rate of 2000 to 5000
seconds. Since my exposure of this guy was 6000 seconds it may have
varied 3 times during my exposure! Thus catching this isn't easy, nor
would I try. I knew this before I took the image.

What I didn't know was that it shares the field with a very faint
nebulosity. This nebulosity isn't listed in any catalog I have, nor
does it appear to be galactic cirrus. Not expecting it I severely
underexposed for it, especially the color frames which are very noisy.
Don't consider the color of this faint nebulosity as at all correct, the
color is mostly noise. If anyone knows what it is please let me know.
I need to go back and try a much longer exposure. But something is
reflecting into my field. When I centered the nebula a rather bright
ghostly nebula appeared to the west of the nebula. I have no idea where
the reflection came from, M15? To get rid of it I had to lower the
object. Raising it didn't help. Since the nebula is mostly "below" the
planetary that means I lost some of it, though I didn't realize it at
the time. I can't find any reliable distance data for this planetary.
Again, if anyone knows let me know.

Conditions went from fair to bad during this exposure. The loss of
resolution caused the blue and especially green frames to be "defocused"
creating the odd blue-green halos around bright stars as well as making
them larger than usual. Yet another reason to redo this one but I have
such a backlog of objects not taken the first time it is hard to go back
and reimage those I should.

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



  #5  
Old October 10th 08, 04:45 AM posted to alt.binaries.pictures.astro
J McBride
external usenet poster
 
Posts: 274
Default ASTRO: NGC 7094 and a bonus nebula

Hey Man, I'm not arguing what it is. I'm just saying that I'm not surprised
that you picked it up. That stuff is everywhere up there and I hope to have
a imaging system strong enough to capture it some day.

Joe


"Rick Johnson" wrote in message
ster.com...
Joe,
As I mentioned in the post, I don't think this is galactic cirrus as you
mention in connection with these other objects. The nebula in my shot
is strongest in red and virtually absent in blue. Cirrus would show
nearly equally in all three from the images of it I've seen. Also I've
taken these other objects at the same or longer exposure time and while
I can find the cirrus in them it is too weak to bring out. This is
several times stronger than any cirrus I know of. Nor does it have the
wispy dusty look of cirrus. This looks more like ERE emission from the
response in the RGB filters rather than reflective though some Halpha
may be involved as well. A shot with the H alpha filter would answer
the latter. Since it was so weak in blue H alpha can't be a major
player or I'd see H beta in the blue. Though it was getting lower in
the sky when I took the blue so it might be lost to blue extinction but
I wasn't that low per the headers. But ERE is very smooth, not clumpy
like this so I don't like that idea either. I was hoping someone might
already know of it. I see no hint of it in my M15 shot but that is also
a far shorter exposure using only 2 minute subs to prevent the core from
saturating.

Rick

J McBride wrote:

Nice image Rick! That planetary is very blue. That extra nebula is not
surprising though. I saw an image on Astromart yesterday posted by

Roland
Christen that showed intergalactic dust up to and around NGC 7331 and
Stephen's Quintet. I have also seen images of similar nebula around

M81-m82
taken by Tom Davis with a 10ASA.

Joe


"Rick Johnson" wrote in message
ster.com...

Despite my return to galaxies last post I'm not done with planetary
nebula. NGC 7094 a planetary in Pegasus not far from the famous
globular cluster M15. The central star in this nebula is a rather odd
star. It is known as a hybrid PG 1159 star. What this means is that
it, first off, has an unusual amount of hydrogen left in its atmosphere.
Secondly it is a variable star. White dwarf stars are normally dead
stars only giving off heat and light stored in them when their nuclear
furnaces were still working. When they die they throw off the outer
atmosphere that still has hydrogen, creating the planetary nebula, and
retaining the core of heavier elements created by the nuclear furnace.
They get a small amount of energy from gravitational collapse as they
cool but they shouldn't very in brightness. But some do. It is thought
that the outer atmosphere of the star becomes more or less opaque
depending on the ionization level of certain heavy elements such as iron
in the atmosphere. It is this variation of ionization that makes the
star appear to vary in brightness. In fact it doesn't, its just that
the atmosphere blocks the light at time. Such cycles are very
irregular. In this case the star varies at a rate of 2000 to 5000
seconds. Since my exposure of this guy was 6000 seconds it may have
varied 3 times during my exposure! Thus catching this isn't easy, nor
would I try. I knew this before I took the image.

What I didn't know was that it shares the field with a very faint
nebulosity. This nebulosity isn't listed in any catalog I have, nor
does it appear to be galactic cirrus. Not expecting it I severely
underexposed for it, especially the color frames which are very noisy.
Don't consider the color of this faint nebulosity as at all correct, the
color is mostly noise. If anyone knows what it is please let me know.
I need to go back and try a much longer exposure. But something is
reflecting into my field. When I centered the nebula a rather bright
ghostly nebula appeared to the west of the nebula. I have no idea where
the reflection came from, M15? To get rid of it I had to lower the
object. Raising it didn't help. Since the nebula is mostly "below" the
planetary that means I lost some of it, though I didn't realize it at
the time. I can't find any reliable distance data for this planetary.
Again, if anyone knows let me know.

Conditions went from fair to bad during this exposure. The loss of
resolution caused the blue and especially green frames to be "defocused"
creating the odd blue-green halos around bright stars as well as making
them larger than usual. Yet another reason to redo this one but I have
such a backlog of objects not taken the first time it is hard to go back
and reimage those I should.

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