APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

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Expand view Topic review: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Chris Peterson » Sat Jun 18, 2011 8:52 pm

Ann wrote:What I find incredible about globular clusters is that they are found in all big galaxies (and in some small galaxies, too), and most of the globulars are between ten and twelve billion years old. What incredible forces swept across the universe between ten and twelve billion years ago to create these amazing super star clusters everywhere in the cosmos?
I don't think anything "swept across the universe" to create globular clusters. It seems likely they are simply a byproduct of galaxy formation, and it is therefore not incredible at all that they are found around large galaxies. It would be much more remarkable if they existed in some galaxies but not others.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Ann » Sat Jun 18, 2011 8:26 pm

What I find incredible about globular clusters is that they are found in all big galaxies (and in some small galaxies, too), and most of the globulars are between ten and twelve billion years old. What incredible forces swept across the universe between ten and twelve billion years ago to create these amazing super star clusters everywhere in the cosmos?

Ann

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Chris Peterson » Sat Jun 18, 2011 2:31 pm

garry wrote:In globular clusters, if Gravity is the only dominant force, what is it doing differently from "normal galaxies"? Gravity is a known force at present. To say it is the only force is short sighted. There may be other forces involved that we have not discovered yet.
I don't doubt that other forces play a role. For instance, we have good reason to believe that hydrodynamic drag and electromagnetic momentum transfer effects are important in creating accretion discs in planetary systems, and possibly in galaxies. Without those effects, there is no mechanism to produce a disc, and you get a spherical halo, as we see in the dark matter surrounding galaxies. Nevertheless, gravity is dominant force in bringing these structures together.

There is no reason the same basic mechanisms can't produce different physical structures. We see that all the time. Assuming (as is reasonable) that the conditions in which spiral galaxies and globular clusters form are different, different structures are hardly surprising.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by garry » Sat Jun 18, 2011 6:30 am

Chris Peterson wrote:
neufer wrote:Then how do you explain the spherical symmetry of globular clusters :?:
Spherical symmetry doesn't argue against gravitational forces being the primary factor in the formation of a many-star body, whether a galaxy (and there are spherical galaxies) or a cluster.

I'm not trying to describe any detail about how galaxies or clusters form (it's an area of active research, of course), only arguing that in the broadest of terms, gravity is probably the dominant force involved.
In globular clusters, if Gravity is the only dominant force, what is it doing differently from "normal galaxies"? Gravity is a known force at present. To say it is the only force is short sighted. There may be other forces involved that we have not discovered yet.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by jwhite28625 » Fri Jun 17, 2011 4:37 pm

Beautiful! I just wonder what it would be like to be on a planet inside the cluster and look up at night sky. It would have to be mind blowing!

Jim

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by neufer » Thu Jun 16, 2011 9:12 pm

rstevenson wrote:
Note to self: Never give Art an opening.
But you're a donut :!:

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by owlice » Thu Jun 16, 2011 7:41 pm

rstevenson wrote:Note to self: Never give Art an opening. Always use the speel chacker.

Rob
Oh, Rob, you know Art: he'll make his own opening if no one gives him one! Think of providing an opening as channeling the energy in the direction you want it to go, rather than... well, you know... :shock:

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by rstevenson » Thu Jun 16, 2011 4:39 pm

neufer wrote:
rstevenson wrote: Unlike galaxies, globular clusters have sublety.
sublet: Property leased by one lessee to another.
rstevenson wrote:
Note to self: Never give Art an opening. Always use the speel chacker.

Rob

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Ann » Thu Jun 16, 2011 3:16 pm

rstevenson wrote:Unlike galaxies, globular clusters have sublety. Those brazen galaxies are just showing off, waving their skirts all over the place, flaring and glaring at us. Give me a quiet old cluster any day.

Rob
Thanks for setting me straight with subtlety, Rob! (Hmmm... sounds like a song, doesn't it?)

Ann

P.S. Now I know what I was thinking of. "Killing me softly with his song", that's it.
Click to play embedded YouTube video.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by owlice » Thu Jun 16, 2011 3:13 pm

Yes, yes, I know globular clusters are unlike galaxies; that was the point of my question! Sheeesh!! Why are images of galaxies and discussion thereof posted on a thread about a (gorgeous!) image of a (lovely!) globular cluster? What's the connection between Ann's post and the thread's topic? I'm trying to understand why she posted what she posted, because I'm not getting it and I hope she will enlighten me! Was yesterday opposite day or some such?

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by neufer » Thu Jun 16, 2011 2:50 pm

rstevenson wrote:
Unlike galaxies, globular clusters have sublety.
sublet: Property leased by one lessee to another.

Anagrams: bluest, bustle, subtle
rstevenson wrote:
Those brazen galaxies are just showing off, waving their skirts all over the place, flaring and glaring at us.
http://asterisk.apod.com/viewtopic.php? ... 60#p150520
rstevenson wrote:
Give me a quiet old cluster any day.
    • Coriolanus Act 4, Scene 6
    MENENIUS: We loved him but, like beasts
    • And cowardly nobles, gave way unto your clusters,

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Chris Peterson » Thu Jun 16, 2011 2:40 pm

rstevenson wrote:Unlike galaxies, globular clusters have sublety. Those brazen galaxies are just showing off, waving their skirts all over the place, flaring and glaring at us. Give me a quiet old cluster any day.
Hmmm... I have now constructed slightly richer (although possible wrong!) images in my mind of both Ann and yourself. <g>

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by rstevenson » Thu Jun 16, 2011 2:33 pm

Unlike galaxies, globular clusters have sublety. Those brazen galaxies are just showing off, waving their skirts all over the place, flaring and glaring at us. Give me a quiet old cluster any day.

Rob

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by neufer » Thu Jun 16, 2011 2:04 pm

owlice wrote:
Ann wrote:
What is it about globular clusters that makes me find them so much less interesting than most spiral galaxies? I think it is entropy. Globular clusters strike me as systems with a very high degree of entropy, where everything is very well mixed, and few obvious structures can be seen. Compare globular clusters with spiral galaxies, which often walk on the wild side and have amazing personalities.
I'm not getting the connection between all these images of galaxies and the topic of this thread; what am I missing here?
Because unlike globular clusters
Ann's galaxies have got personality;
Walk with personality;
Talk with personality;
Smile with personality;
Charm with personality;
Love with personality;
Plus they've got so much less en-tro-py.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by owlice » Thu Jun 16, 2011 9:45 am

Ann wrote:What is it about globular clusters that makes me find them so much less interesting than most spiral galaxies? I think it is entropy. Globular clusters strike me as systems with a very high degree of entropy, where everything is very well mixed, and few obvious structures can be seen. Compare globular clusters with spiral galaxies, which often walk on the wild side and have amazing personalities. This is NGC 1087:

Image

Infrared NGC 1097 by Spitzer.
Visual NGC 1097, by R. Jay GaBany.

Image

Ultraviolet NGC 1097, by GALEX.
Circumnuclear ring of star formation in NGC 1097, by Hubble.

Wow, you know. But I have to admit that Omega Centauri looks better than NGC 1097 through an amateur telescope!

Ann
Ann,

I'm not getting the connection between all these images of galaxies and the topic of this thread; what am I missing here? Please enlighten me; thanks!

Owlice

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by kaigun » Thu Jun 16, 2011 4:17 am

Omega can be seen from some northern places I think even 40 degrees North. It's just spectacular with binos rising above the horizon in a dark place. Right now from my location is almost at the Zenit (75 degrees at 9pm).
Unfortunately (for viewing Omega Cen) I live at 61 degrees N, in Alaska. I missed that planetary line up earlier, too.

APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Ann » Thu Jun 16, 2011 4:09 am

What is it about globular clusters that makes me find them so much less interesting than most spiral galaxies? I think it is entropy. Globular clusters strike me as systems with a very high degree of entropy, where everything is very well mixed, and few obvious structures can be seen. Compare globular clusters with spiral galaxies, which often walk on the wild side and have amazing personalities. This is NGC 1087:

Image

Infrared NGC 1097 by Spitzer.
Visual NGC 1097, by R. Jay GaBany.

Image

Ultraviolet NGC 1097, by GALEX.
Circumnuclear ring of star formation in NGC 1097, by Hubble.

Wow, you know. But I have to admit that Omega Centauri looks better than NGC 1097 through an amateur telescope!

Ann

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Joe Stieber » Wed Jun 15, 2011 11:04 pm

luigi wrote: Omega can be seen from some northern places I think even 40 degrees North. It's just spectacular with binos rising above the horizon in a dark place. Right now from my location is almost at the Zenit (75 degrees at 9pm).
Boomer it's raining for today's eclipse. I'm so so so mad about that :D
At a declination of -47.5 degrees, Omega Centauri would just reach the horizon at +42.5 degrees latitude (actually, it would be slightly higher because of atmospheric refraction). I've seen it at a bit more than 3 degrees altitude from a latitude of +39.25 degrees in southern New Jersey, USA, looking over the Delaware Bay. Even at that low altitude, it's impressive on a clear night. I can only imagine what it looks like at a favorable altitude.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Joe » Wed Jun 15, 2011 7:14 pm

I still remember the first globular cluster I saw with my telescope. What an amazing site. They still are my favorite objects to look at. Great image today and thank you Chris for enlightening me about the density of the clusters. I assumed that they were way more dense than this area of the galaxy, but it would make sense that they are less dense on the outer regions and get extremely dense on the way in.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Chris Peterson » Wed Jun 15, 2011 6:47 pm

neufer wrote:Then how do you explain the spherical symmetry of globular clusters :?:
Spherical symmetry doesn't argue against gravitational forces being the primary factor in the formation of a many-star body, whether a galaxy (and there are spherical galaxies) or a cluster.

I'm not trying to describe any detail about how galaxies or clusters form (it's an area of active research, of course), only arguing that in the broadest of terms, gravity is probably the dominant force involved.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by neufer » Wed Jun 15, 2011 6:40 pm

Chris Peterson wrote:
It seems likely that the processes involved in forming globular clusters are similar to those involved in forming galaxies, and that these are dynamical interactions involving gravity.
Then how do you explain the spherical symmetry of globular clusters :?:

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Chris Peterson » Wed Jun 15, 2011 5:45 pm

Wolf Kotenberg wrote:there is an area in the Pacific ocean where the floating garbage collects and makes a giant circle of solid stuff. I never personally seen it so i rely on newsmedia to tell the news consumer to be telling the facts. Is this the same kind of principle that could cause a globular cluster to form ? Al,kl the magnetic lines of force point to a place in this giant Universe .
Magnetic forces play almost no role in the Universe on any sort of large scales (outside of stellar environments) because they are simply too small.

It seems likely that the processes involved in forming globular clusters are similar to those involved in forming galaxies, and that these are dynamical interactions involving gravity.

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by Wolf Kotenberg » Wed Jun 15, 2011 5:40 pm

there is an area in the Pacific ocean where the floating garbage collects and makes a giant circle of solid stuff. I never personally seen it so i rely on newsmedia to tell the news consumer to be telling the facts. Is this the same kind of principle that could cause a globular cluster to form ? Al,kl the magnetic lines of force point to a place in this giant Universe .

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by luigi » Wed Jun 15, 2011 5:17 pm

kaigun wrote:
luigi wrote:Fantastic Image, every star is clearly defined, millions of them!

I live in the South Hemisphere so Omega Cen is almost always high in the sky. At naked eye it looks like a blurry star, with common binoculars it's a fantastic object, quite a beautiful sight.
I live too far north to see Omega Centauri now, but I have enjoyed it in the past while in the Southern Hemisphere. I found Delta Cru and Gacrux useful as pointers. I was in the Navy at time, we used 7x50 binoculars, 20x120 ship's binoculars (only useful if the sea was dead calm), and Night Vision Goggles. The NVGs did not magnify, but the light amplification was cool. The only light pollution we worried about was the Moon.
Omega can be seen from some northern places I think even 40 degrees North. It's just spectacular with binos rising above the horizon in a dark place. Right now from my location is almost at the Zenit (75 degrees at 9pm).
Boomer it's raining for today's eclipse. I'm so so so mad about that :D

Re: APOD: Millions of Stars in Omega Centauri (2011 Jun 15)

by kaigun » Wed Jun 15, 2011 4:28 pm

luigi wrote:Fantastic Image, every star is clearly defined, millions of them!

I live in the South Hemisphere so Omega Cen is almost always high in the sky. At naked eye it looks like a blurry star, with common binoculars it's a fantastic object, quite a beautiful sight.
I live too far north to see Omega Centauri now, but I have enjoyed it in the past while in the Southern Hemisphere. I found Delta Cru and Gacrux useful as pointers. I was in the Navy at time, we used 7x50 binoculars, 20x120 ship's binoculars (only useful if the sea was dead calm), and Night Vision Goggles. The NVGs did not magnify, but the light amplification was cool. The only light pollution we worried about was the Moon.

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