APOD: NGC 7331 and Beyond (2014 Mar 01)

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APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by APOD Robot » Sat Mar 01, 2014 5:07 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 by galaxies that lie beyond the gorgeous island universe. The 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 here through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is also known as the Deer Lick Group.

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by BDanielMayfield » Sat Mar 01, 2014 5:31 am

The sharpness of this image brings out NGC 7331's large central bulge very well. It's core therefore should contain a very massive SMBH.

Wonderful image. My thanks to all who brought it to us.

Bruce
Last edited by BDanielMayfield on Sat Mar 01, 2014 4:12 pm, edited 1 time in total.
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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by Ann » Sat Mar 01, 2014 7:18 am

Note the diffuse "halo" that reaches "up" and "down" a good distance from the center of NGC 7331. We see the Andromeda galaxy from more or less the same sort of perspective, but I dare you to find a picture of Andromeda that shows the same kind of "halo" emanating from the center of our large "sister galaxy".

By the way, the "Deer Lick Group". Isn't that a wonderful name, although I, at least, have to wonder what it is supposed to make us think about?

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by Nitpicker » Sat Mar 01, 2014 7:33 am

I'm guessing that deer lick is a kind of plant salty patch of ground favoured by deer near Deer Lick Gap, in North Carolina.

Great APOD.

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by rstevenson » Sat Mar 01, 2014 12:20 pm

tannaberton wrote:"and so lie roughly ten times farther away"...try three times..it's an inverse square so the others lie about three times as far away. Ten times as far means they would be 1/100 the size. Laughed at the black hole reference..The Universe is Electric...see u in the heavens.
You seem to be confused. If the reference had been to luminosity, then yes, the inverse square law applies. But linear (or apparent) size varies with linear distance, so if a galaxy appears to be 1/10th the size, it's about 10 times further away, as stated.

As for your reference to an electric universe, you're in the wrong forum for that stuff -- but you knew that, of course.

Rob

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by orin stepanek » Sat Mar 01, 2014 12:34 pm

It's gonna be an awesome wallpaper! 8-) :D
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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by neufer » Sat Mar 01, 2014 2:14 pm

Nitpicker wrote:
I'm guessing that deer lick is a kind of plant salty patch of ground favoured by deer near Deer Lick Gap, in North Carolina.
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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by BDanielMayfield » Sat Mar 01, 2014 2:39 pm

BDanielMayfield wrote:The sharpness of this image brings out NGC 7331's large central bulge very well. It's core therefore should contain a very massive SMBH.
tannaberton wrote:Laughed at the black hole reference..The Universe is Electric..
While at times I make comments where amusement is intended, that wasn’t the case here.

Under the entry Bulge (astronomy)
Wikipedia wrote:In astronomy, a bulge is a tightly packed group of stars within a larger formation. The term almost exclusively refers to the central group of stars found in most spiral galaxies (see Galactic spheroid). Bulges were historically thought to be elliptical galaxies that happen to have a disk of stars around them, but high resolution images using the Hubble Space Telescope have revealed that many bulges have properties that are more like spiral galaxies. It is now thought that there are at least two types of bulges, bulges that are like ellipticals and bulges that are like spiral galaxies.
...
Most bulges are thought to host a supermassive black hole at their center. Such black holes by definition can not be observed (light cannot escape them), but various pieces of evidence strongly suggest their existence, both in the bulges of spiral galaxies and in the centers of ellipticals. The masses of the black holes correlate tightly with bulge properties; the tightest such correlation, the M–sigma relation, is between black hole mass and the velocity dispersion of stars in the bulge. Until recently it was thought that one could not have a supermassive black hole without a bulge around it, but galaxies hosting supermassive black holes without accompanying bulges have now been observed.
Last edited by BDanielMayfield on Sat Mar 01, 2014 4:13 pm, edited 1 time in total.
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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by Psnarf » Sat Mar 01, 2014 3:16 pm

For your wallpaper, I suggest the full-sized image: http://stargazer-observatory.com/wp-con ... GC7331.jpg
Wow! The sense of depth and all of those background galaxies, some no larger than the width of a nearby star, gives one pause. I could stare at that all day.
PS. There are indeed background galaxies 1/100 the size. Some appear to be a small star with a tail. Pardon me while I have a strange interlude: "Dear" is misspelled. Off I go to lick my dear....

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by starsurfer » Sat Mar 01, 2014 4:41 pm

There is indeed a lot of dust in this area as there is across pretty much all of Pegasus! One widefield image that shows it is this one by Martin Pugh.

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by jonpugh » Sat Mar 01, 2014 6:11 pm

Observations of the large scale structure of the universe show that galaxies lie along filaments of gas and dark matter, gathered into clusters and super-clusters at the junctions of these filaments. Thus, the real question is, are any of these visibly associated galaxies joined by these sorts of filaments, or are we seeing across the empty space between threads?

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Re: APOD: NGC 7331 and Beyond (2014 Mar 01)

Post by Ron-Astro Pharmacist » Mon Mar 03, 2014 11:23 pm

jonpugh wrote:Observations of the large scale structure of the universe show that galaxies lie along filaments of gas and dark matter, gathered into clusters and super-clusters at the junctions of these filaments. Thus, the real question is, are any of these visibly associated galaxies joined by these sorts of filaments, or are we seeing across the empty space between threads?
In this month's Scientific American article "Dwarf Galaxies and the Dark Web" the author comments that the Milky Way's companion galaxies are oriented, by observation, to generally fit along a single plane when computer simulations predict otherwise.

A few days back there was a graphic in the description of Gould's Belt.

http://www.newscientist.com/data/images ... 350901.jpg

illustrating the plane of the Milky Way with respect to the plane of Gould's Belt to point out the relation to loose clusters of young massive stars.

Makes me wonder if there ever has been an attempt to study the various planes that exist in the cosmos to find if there are coorelations at differing sizes or scales. i.e. Are there spin relationships anywhere on the continuum from quarks to galaxies? Guess we would need a celestial coordinate system for that to occur. Luckily I can always call home : Plane T - Earth :lol2:
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