APOD: M72: A Globular Cluster of Stars (2010 May 12)

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APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by APOD Robot » Wed May 12, 2010 3:51 am

Image M72: A Globular Cluster of Stars

Explanation: Globular clusters once ruled the Milky Way. Back in the old days, back when our Galaxy first formed, perhaps thousands of globular clusters roamed our Galaxy. Today, there are less than 200 left. Many globular clusters were destroyed over the eons by repeated fateful encounters with each other or the Galactic center. Surviving relics are older than any Earth fossil, older than any other structures in our Galaxy, and limit the universe itself in raw age. There are few, if any, young globular clusters in our Milky Way Galaxy because conditions are not ripe for more to form. Pictured above by the Hubble Space Telescope are about 100,000 of M72's stars. M72, which spans about 50 light years and lies about 50,000 light years away, can be seen with a small telescope toward the constellation of the Water Bearer (Aquarius).

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Astronut

Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Astronut » Wed May 12, 2010 4:31 am

Looks kinda like any other run of the mill section of space that has a conglomeration of white spots -- Until you click on the picture once or twice -- then it becomes one of those "wow" shots :!:

Vincent Pinto

Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Vincent Pinto » Wed May 12, 2010 4:32 am

Back in the "old days"? :? :o
Not any older than six thousand years!

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by tesla » Wed May 12, 2010 6:11 am

With a globular cluster, what are the dynamics that form the group? Are they static in relationship with each other? Or are they moving in to a central point or expanding? If gravity is the driving power behind elliptical galaxies that have spin, what happened to Globular?

kovil2

Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by kovil2 » Wed May 12, 2010 9:12 am

My understanding is that the stars in globular clusters do 'pincushion' orbits, mostly, about the centre of mass by gravitational action. However, I have no observational data on this.

Thanks, APOD! This is a good one !
I'd never seen a globular cluster be so exciting before !!!
It is odd, as to why our galaxy would have 200 roaming 'banditos' so to speak, as per the mainstream of starcreation in the arm structures.

Now, as to the 'age' of globular clusters, that is another matter entirely.

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Hofi » Wed May 12, 2010 12:49 pm

Great image! I like the background galaxies most! There are really nice edge-on ones!

Does anyone of you know what these orange to red dots are that appear all over the image?
Best wishes,
Thomas Hofstätter

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by biddie67 » Wed May 12, 2010 1:31 pm

I was wondering some of the same things that tesla (above) mentioned. What is different in the gravitational forces that cause some globular clusters to apparently resolve themselves into a disk-like galaxy as our galaxy but others still remain as globular clusters? What kind of rotational motions do they have?

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Hofi » Wed May 12, 2010 1:41 pm

biddie67 wrote:I was wondering some of the same things that tesla (above) mentioned. What is different in the gravitational forces that cause some globular clusters to apparently resolve themselves into a disk-like galaxy as our galaxy but others still remain as globular clusters? What kind of rotational motions do they have?
Good question!
I'm looking forward to the answer! I could only imagine that for any reason star-forming went much faster in globular clusters than in galaxies.
Best wishes,
Thomas Hofstätter

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by stenodrin » Wed May 12, 2010 1:47 pm

Great APOD today,
THANK YOU by me and bt my heart!!!
stefanodrin

Vincent Pinto

Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Vincent Pinto » Wed May 12, 2010 1:51 pm

Anyone know why some of the larger (and possibly nearer) objects display the diffraction spikes but not the smaller objects? Does this have to do with the fact that aren't enough photons from the smaller ones to diffract off the mirror supports? Or that there will always be the diffractions but not enough to see them on the image? Thanks.

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Scantzen » Wed May 12, 2010 2:11 pm

Vincent,

I assumed the diffraction spikes were caused by stars that are within our galaxy, and therefore closer and brighter. I've seen other images like this, and that has been the explanation in the past. I have no idea if I'm right, however!

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by bystander » Wed May 12, 2010 2:13 pm

M72 is in our own galaxy.

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Chris Peterson » Wed May 12, 2010 2:15 pm

tesla wrote:With a globular cluster, what are the dynamics that form the group? Are they static in relationship with each other? Or are they moving in to a central point or expanding? If gravity is the driving power behind elliptical galaxies that have spin, what happened to Globular?
The stars are gravitationally bound, which means all are in orbits around their perceived center of mass. That is generally at the center of the cluster, of course, but since the star density is so high, the individual stars interact with their neighbors as well. The result is that each star follows a highly perturbed orbit. Occasionally, a star is sufficiently perturbed to be ejected from the cluster completely- a process called evaporation. This limits the lifetime of a globular cluster to the order of 10 billion years.
Chris

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by owlice » Wed May 12, 2010 2:47 pm

Hofi wrote:Great image! I like the background galaxies most! There are really nice edge-on ones!
There are also some lovely spirals!

And agree: great image!
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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Hofi » Wed May 12, 2010 3:21 pm

owlice wrote:
Hofi wrote:Great image! I like the background galaxies most! There are really nice edge-on ones!
There are also some lovely spirals!
You are right! If you have a close look, you can even see some background nebulae! ... Really great stuff!
Best wishes,
Thomas Hofstätter

http://hidden-space.at.tf

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by KJackson » Thu May 13, 2010 5:01 am

I agree: a great image!
bystander wrote:M72 is in our own galaxy.
I'm not sure what is meant by "in" our own galaxy. I was under the impression that most globulars orbit the galactic center but aren't part of the galactic disc. M72 is about 53,000 light years from the galactic center but the dimensions of the galactic disc are approx 12,000 x 100,000 light years so it might or might not be part of the disc. I found this picture that shows globular outsides of the galactic disc. Does any know where M72 is located with respect to the galactic disc?

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Case » Thu May 13, 2010 6:59 am

KJackson wrote:Does any know where M72 is located with respect to the galactic disc?
Image
Courtesy of Think Astronomy Software.
I, for one, like Roman numerals.

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by DavidLeodis » Thu May 13, 2010 12:02 pm

Lovely picture. Clicking on it when online brings up a wider field-of-view that has some galaxies that are not seen in the APOD. There is a particularly large spiral galaxy to the bottom left corner. I wonder what that galaxy is called (assuming that it has a name)?
:rocketship: :owl: <<< those two smilies are from the "View more smilies" link. The owl is cute! :)

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by owlice » Thu May 13, 2010 12:38 pm

DavidLeodis wrote:Lovely picture. ... :owl: The owl is cute! :)
I agree!! :ssmile:
A closed mouth gathers no foot.

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by DavidLeodis » Thu May 13, 2010 12:59 pm

owlice wrote:
DavidLeodis wrote:Lovely picture. ... :owl: The owl is cute! :)
I agree!! :ssmile:
I :) ed at that. The :owl: is a 8-) smilie for your member name owlice. :wink:

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by sirnelson » Fri May 14, 2010 2:08 am

Since these represent some of the oldest in the galaxy and the stars are relvatively close together - far closer than the stars in our neighborhood - I have to wonder about the forms of life that might exist within these clusters. If life forms there have evolved and survived, might their proximity to each other possibly create the kind of scenarios as depicted in our more popular science fiction? Scenarios where differing life forms interact with some regularity. It is an intriguing thought.

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Re: APOD: M72: A Globular Cluster of Stars (2010 May 12)

Post by Chris Peterson » Fri May 14, 2010 2:15 am

sirnelson wrote:Since these represent some of the oldest in the galaxy and the stars are relvatively close together - far closer than the stars in our neighborhood - I have to wonder about the forms of life that might exist within these clusters. If life forms there have evolved and survived, might their proximity to each other possibly create the kind of scenarios as depicted in our more popular science fiction? Scenarios where differing life forms interact with some regularity. It is an intriguing thought.
It is generally thought that planetary systems are rare to non-existent in globulars, because gravitational perturbations from nearby stars will make them unstable. Any planets that survive are likely to be very close to their parent star, and therefore poor candidates for any sort of life as we imagine possible.
Chris

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