APOD: NGC 7331 and Beyond (2014 Dec 18)

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APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by APOD Robot » Thu Dec 18, 2014 5:09 am

Image NGC 7331 and Beyond

Explanation: Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. The effect is further enhanced in this sharp image from a small telescope by galaxies that lie beyond the gorgeous island universe. The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Seen through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is known as the Deer Lick Group.

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Beyond » Thu Dec 18, 2014 5:17 am

I found NGC7331 easily enough, but try as i might, i just couldn't find me. I guess the telescope just couldn't see far enough. :lol2:
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by ta152h0 » Thu Dec 18, 2014 5:21 am

If this thing is 50 million light-years away, can we infer the Big Bang is 13.4 billion light years away, somewhere out there ??
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Ann » Thu Dec 18, 2014 5:30 am

Oh, that is so interesting!

I don't have access to my software here, but I have to note the presence of some extended bluish "fluff" in the lower left part of the image. I suppose it could either be some galactic cirrus associated with the Milky Way, or else it might be the brightest part of a large, faint outer arm or halo of NGC 7331.

There are a few galaxies apart from NGC 7331 and the Deer Lick Group that caught my attention. The most interesting one is located at about 2 o'clock. It is elliptical in shape, has an obvious nucleus, and is surrounded on both sides by slightly bluish tidal(?) extensions. I have to wonder if this galaxy is a dwarf, associated with NGC 7331, and if the bluish extensions are caused by the galaxy's interaction with NGC 7331. The fact that the smaller galaxy has a definite nucleus is perhaps a sign that it is a large galaxy in its own right, but on the other hand there really are nucleated dwarfs.

There s a small, faint smudge of a galaxy at about 5 o'clock that must definitely be a dwarf galaxy, quite possibly associated with NGC 7331. Above and to the left of that small dwarf is a yellowish elliptical which seems to have two nuclei, one yellow and one blue! Although I suppose that the blue "nucleus" might in fact be a superimposed star.

Note the massive "inner halo" of NGC 7331. It could well be that the picture has been processed to bring out faint details not only in NGC 7331 itself but in its satellite galaxies, too.

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Nitpicker » Thu Dec 18, 2014 5:35 am

Beyond wrote:I found NGC7331 easily enough, but try as i might, i just couldn't find me.
You obviously didn't notice the voids.

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Nitpicker » Thu Dec 18, 2014 5:50 am

ta152h0 wrote:If this thing is 50 million light-years away, can we infer the Big Bang is 13.4 billion light years away, somewhere out there ??
http://en.wikipedia.org/wiki/Observable_universe
The best estimate of the age of the universe as of 2013 is 13.798 ± 0.037 billion years but due to the expansion of space humans are observing objects that were originally much closer but are now considerably farther away (as defined in terms of cosmological proper distance, which is equal to the comoving distance at the present time) than a static 13.8 billion light-years distance. It is estimated that the diameter of the observable universe is about 28 billion parsecs (93 billion light-years), putting the edge of the observable universe at about 46–47 billion light-years away.

ShaileshS

Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by ShaileshS » Thu Dec 18, 2014 7:01 am

I didn't understand - "The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away.". What does it mean ? What's the underlying calculation or correlation ? Thanks.

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by geckzilla » Thu Dec 18, 2014 7:07 am

ShaileshS wrote:I didn't understand - "The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away.". What does it mean ? What's the underlying calculation or correlation ? Thanks.
It's just a perspective thing. If you assume all of the galaxies are around the same average dimensions, then you can guess their distance from one another based upon that. If a bunch of people held their hands in your field of view, you could guess how far away from you they were based on how small their hands got. Anyway, this sort of estimate is prone to error because galaxies can vary greatly in actual size.
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Boomer12k » Thu Dec 18, 2014 8:01 am

Really great shot...

It looks like an Elliptical Galaxy that then gained dust lanes...it seems to have very large top and bottom hubs to it.

Ann pointed this out once with M104 I think it was....this looks similar...maybe a "small merger"???

Another might be M87....which we see edge on...

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by songwriterz » Thu Dec 18, 2014 1:02 pm

Ann wrote:Oh, that is so interesting!

I don't have access to my software here, but I have to note the presence of some extended bluish "fluff" in the lower left part of the image. I suppose it could either be some galactic cirrus associated with the Milky Way, or else it might be the brightest part of a large, faint outer arm or halo of NGC 7331.

There are a few galaxies apart from NGC 7331 and the Deer Lick Group that caught my attention. The most interesting one is located at about 2 o'clock. It is elliptical in shape, has an obvious nucleus, and is surrounded on both sides by slightly bluish tidal(?) extensions. I have to wonder if this galaxy is a dwarf, associated with NGC 7331, and if the bluish extensions are caused by the galaxy's interaction with NGC 7331. The fact that the smaller galaxy has a definite nucleus is perhaps a sign that it is a large galaxy in its own right, but on the other hand there really are nucleated dwarfs.

There s a small, faint smudge of a galaxy at about 5 o'clock that must definitely be a dwarf galaxy, quite possibly associated with NGC 7331. Above and to the left of that small dwarf is a yellowish elliptical which seems to have two nuclei, one yellow and one blue! Although I suppose that the blue "nucleus" might in fact be a superimposed star.

Note the massive "inner halo" of NGC 7331. It could well be that the picture has been processed to bring out faint details not only in NGC 7331 itself but in its satellite galaxies, too.

Ann
In the background, at about 11 o'clock I see a great 3-armed, barred galaxy. Does anyone know the designation of that particular galaxy? Any other, better photos of it anywhere?

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by geckzilla » Thu Dec 18, 2014 1:18 pm

songwriterz wrote:In the background, at about 11 o'clock I see a great 3-armed, barred galaxy. Does anyone know the designation of that particular galaxy? Any other, better photos of it anywhere?
That's NGC 7337. This is a pretty good picture of it. A quick search didn't turn up anything much better, if at all.
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Joules » Thu Dec 18, 2014 1:49 pm

enhanced in this sharp image from a small telescope
Small as in a 150 mm refractor, or as in a 20" Cassegrain?
I don't see that info at the Hallas' website.
Regardless, nice shot! Someone has dark skies.

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by rstevenson » Thu Dec 18, 2014 1:59 pm

ta152h0 wrote:If this thing is 50 million light-years away, can we infer the Big Bang is 13.4 billion light years away, somewhere out there ??
According to our current best models and theories, bolstered strongly by observation, the age of the universe is about 13.8 billion years. But that doesn't mean the Big Bang is 13.8 billion light years away from us in a particular direction. In a very real sense, we are in the Big Bang, or what's left of it. Which is the same thing as saying we are in the universe.

Rob

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by songwriterz » Thu Dec 18, 2014 2:03 pm

geckzilla wrote:
songwriterz wrote:In the background, at about 11 o'clock I see a great 3-armed, barred galaxy. Does anyone know the designation of that particular galaxy? Any other, better photos of it anywhere?
That's NGC 7337. This is a pretty good picture of it. A quick search didn't turn up anything much better, if at all.
Thank you!

Hummph! There's only Umpteen Bajillion galaxies out there (give or take a kajillion or two.) You'd figure that someone could've specifically imaged NGC 7337 by now!!!

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Chris Peterson » Thu Dec 18, 2014 2:32 pm

ta152h0 wrote:If this thing is 50 million light-years away, can we infer the Big Bang is 13.4 billion light years away, somewhere out there ??
The Big Bang occurred 13.8 billion years ago. It can't be said to be at any distance at all because it's done. It's over. It's not there anymore. Since the Universe was opaque for a few hundred years after the Big Bang, no photons from that time are visible. But photons were released when the Universe became transparent 380,000 years after the Big Bang. Those photons have been traveling for 13.8 billion years, during which time the Universe they've traveled through has expanded to a radius of 46.6 billion light years. That has resulted in the photons having their wavelength stretched from a peak in the visible to a peak of about a millimeter. We detect that as the cosmic microwave background.

Although we detect these photons here (as we do all photons), they appear to be emanating from a sphere surrounding us, which is the edge of the observable universe. We should be able to see slightly beyond that with something other than light, such as gravitational waves. Beyond that, the fabric of the Universe is expanding at greater than the speed of light, and is therefore causally disconnected from us and forever beyond our ability to detect.
Chris

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by geckzilla » Thu Dec 18, 2014 2:42 pm

songwriterz wrote:Hummph! There's only Umpteen Bajillion galaxies out there (give or take a kajillion or two.) You'd figure that someone could've specifically imaged NGC 7337 by now!!!
Your own logic betrays you. If there are umpteen bajillion galaxies ±1 kajillion, it makes sense that NGC 7337 would be one of the many ignored ones. But the real reason it's not imaged much is because its apparent size is so small. You'd need an exceptional telescope to get a much better picture of it. Tony has a pretty darn good telescope.
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Beyond » Thu Dec 18, 2014 3:34 pm

Nitpicker wrote:
Beyond wrote:I found NGC7331 easily enough, but try as i might, i just couldn't find me.
You obviously didn't notice the voids.
The voids are full of nice nothings.
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Ron-Astro Pharmacist » Thu Dec 18, 2014 3:58 pm

Appears that urban sprawl affects the universe. But at least there are lots of nice neighborhoods. Including today's APOD. A sense of width is fascinating too.

http://www.guidescope.net/galaxies/stephan-deer.htm

I know not what height would yield?
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by profsnape » Thu Dec 18, 2014 4:08 pm

this pic appears to show a progressive canting of the central region from the plane of the galaxy, is it an illusion or is part of the centre presaging somehow over time?

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by curious jay » Thu Dec 18, 2014 5:14 pm

Chris Peterson wrote:the fabric of the Universe is expanding at greater than the speed of light, and is therefore causally disconnected from us and forever beyond our ability to detect.
Is there any guess as to how much faster than light it expands? How can anything travel faster than light?

Guest

Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Guest » Thu Dec 18, 2014 5:23 pm

Ron-Astro Pharmacist wrote:Appears that urban sprawl affects the universe. But at least there are lots of nice neighborhoods. Including today's APOD. A sense of width is fascinating too.

http://www.guidescope.net/galaxies/stephan-deer.htm

I know not what height would yield?
This is one of my favorite regions - using a field of view a little larger than the APOD picture, Stephen's Quintet is only a short pan away. These are the brightest visual targets in the area, and seeing all five members of the quintet can sometimes be tricky, but that puts about a dozen galaxies in a two field-of-view area!

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by ta152h0 » Thu Dec 18, 2014 5:40 pm

" You obviously didn't notice the voids. "

I told you, scientists are funny people
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Ron-Astro Pharmacist » Thu Dec 18, 2014 5:46 pm

Nitpicker wrote:
ta152h0 wrote:If this thing is 50 million light-years away, can we infer the Big Bang is 13.4 billion light years away, somewhere out there ??
http://en.wikipedia.org/wiki/Observable_universe
The best estimate of the age of the universe as of 2013 is 13.798 ± 0.037 billion years but due to the expansion of space humans are observing objects that were originally much closer but are now considerably farther away (as defined in terms of cosmological proper distance, which is equal to the comoving distance at the present time) than a static 13.8 billion light-years distance. It is estimated that the diameter of the observable universe is about 28 billion parsecs (93 billion light-years), putting the edge of the observable universe at about 46–47 billion light-years away.
Since you asked maybe we could call our current caste : The Last Vast Fast Gas from a Blast in the Past that will eventually be flashed or crashed once adequately hashed. :roll: :D

But I think I'll enjoy the current time looking out to the stars and into such nice images on my screen.
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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by profsnape » Thu Dec 18, 2014 5:48 pm

those are not the voids you are looking for

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Re: APOD: NGC 7331 and Beyond (2014 Dec 18)

Post by Chris Peterson » Thu Dec 18, 2014 6:08 pm

curious jay wrote:
Chris Peterson wrote:the fabric of the Universe is expanding at greater than the speed of light, and is therefore causally disconnected from us and forever beyond our ability to detect.
Is there any guess as to how much faster than light it expands? How can anything travel faster than light?
It is a common misconception that nothing can travel faster than light. No information can be transmitted at greater than c, and you can't accelerate anything with mass to a velocity greater than c with respect to its original point. But neither of those are happening in the case of the expansion of the Universe.

Material beyond the edge of our observable universe could be moving at many times c with respect to us. How many times depends on the actual size of the Universe, which is probably many orders of magnitude greater than the size of our observable universe (and is possibly infinitely large).
Chris

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