Understanding stellar birth using old star clusters

Jun 01, 2011

It is now known that most, if not all, of the stars in our Galaxy were born in star clusters. These spherical groupings contain anywhere from a few tens to several million members all milling about under the influence of gravity. But their fate is sealed. All star clusters slowly dissolve over time. "The net effect of this is that their stars eventually become redistributed throughout the Galaxy," said Nathan Leigh, a PhD student at McMaster University and lead author for a study being presented this week at the CASCA 2011 meeting in Ontario, Canada. "This is how we think most of the stars in the Milky Way came to be found in their currently observed locations."

Although we now know that have played an important role in shaping the history of our Galaxy, we still do not understand how their stars are formed. Part of the problem lies in the fact that populations of are typically hidden by a dense veil of gas and dust. This makes it very difficult to directly observe and study regions where stars are currently being born. In order to get around this, have combined observations of star clusters so old that they date back to the beginning of the Universe itself with state-of-the-art simulations for their evolution.

"Unfortunately, most star clusters take so long to dissolve that we cannot actually see it happening. But we now understand how this process occurs, and we can look for its signatures by examining the current appearances of clusters," said Nathan Leigh. "We have gone about this by matching up the clusters we make with our simulations to the ones we actually observe. This tells us about the conditions at the time of their formation."

This has allowed Leigh and collaborators to re-trace the histories of real star clusters, providing for the very first time a glimpse at their formation. To get the job done, they used highly sophisticated observations recently taken with the .

"Remarkably, we are finding that all star clusters more or less share a common history, extending all the way back to their births," said Leigh. "This came as a big surprise to us since it suggests that the problem could be much simpler than we originally thought. Our understanding of not only how stars form, but also the history of our Galaxy, just took a much bigger step forward than we were expecting."

Explore further: Mixing in star-forming clouds explains why sibling stars look alike

Provided by Canadian Astronomical Society

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kevinrtrs
1.4 / 5 (11) Jun 02, 2011
I always marvel at the ability of people to find out things that happened in the past.
For instance, just how exactly did they find out that all stars were born in star clusters?
Was this knowledge gained by some mathematical reconstruction or through actual observation of the birth and subsequent dispersion of stars to their current positions?
Now since we KNOW that no one human being was alive at the time of their formation, this knowledge must have been gained through mathematical reconstruction. In doing so, they'll have made some assumptions about the initial conditions. And there in lies the rub. Who is to say that those assumptions bear any resemblance to what occurred in reality?
Yes, I know, the article does go on to say that all their KNOWledge is based on simulation. The point is that they go about shouting their new-found insight to the world as if it was the truth instead of a simulation. It would be a lot more honest and acceptable if they didn't pretend to know it all.
omatumr
1.5 / 5 (8) Jun 02, 2011
I always marvel at the ability of people to find out things that happened in the past.


We have quantitative information that indicates the Sun and its planets were born in the death throes of a single precursor star.

With kind regards,
Oliver K. Manuel
Tuxford
1.6 / 5 (7) Jun 02, 2011
Perhaps they have trouble seeing the clusters dissolve because they are not actually dissolving? It is not surprising to find stars being born mostly in clusters if you consider regions of higher mass density accelerate the unrecognized new matter nucleation rate. This process is greatly accelerated in the galactic core, the region of highest density, and secondarily in star clusters where the density is higher than average. Clusters grow from within. Why else are most globular clusters so old???
Ethelred
5 / 5 (5) Jun 03, 2011
Yikes. Three posts. Three Cranks.

Dr. Tungsten has to stop turning that crank.

Ethelred

Ethelred
4.4 / 5 (7) Jun 03, 2011
Crank one
For instance, just how exactly did they find out that all stars were born in star clusters?
A variety of forms of evidence supports this. For one we only see stars forming in clusters. For another stars in a cluster tend to have similar chemical ratios and ages. Mostly its because there is no evidence to the contrary despite Crank 2 and 3's silly remarks, and the evidence that there is all supports it.

mathematical reconstruction or through actual observation of the birth
Yes.

subsequent dispersion of stars to their current positions
Obviously not nor is it a requirement.

Now since we KNOW that no one human being was alive at the time of their formation,
Nor was anyone alive 6000 years ago if we go on Kevin's ideas. Yet stuff is in the Bible anyway. Wrong of course but it is there.>>
Ethelred
5 / 5 (6) Jun 03, 2011
Who is to say that those assumptions bear any resemblance to what occurred in reality?
Rational people are who. They use actual observations, simulations, and reason to figure out how things could or could not happened THEN they check all the different results of the those ideas and when they all fit together they make the very reasonable conclusion that they have a model that works. Unlike the model which has a 6000 year old Earth which is a total failure.

Yes, I know, the article does go on to say that all their KNOWledge is based on simulation.
You have a reading problem because they did not say that. They said the simulations match actual observations. Which is a pretty good sign that they know what they are talking about. Unlike claiming that the universe is 6000 years old when we see things billions of light years out.>>
Ethelred
5 / 5 (6) Jun 03, 2011
The point is that they go about shouting
They wrote a paper. That isn't shouting. Perhaps you simply think that everyone goes around on college campuses shouting 'read the Bible' or 'the Universe is old so don't read the Bible' the first is true the second is another of your fantasies.

It would be a lot more honest and acceptable if they didn't pretend to know it all.
Anytime you want to stop pretending you know everything because you read it in thee Bible Kevin how about you let us know? Or at least give us some reason to believe the Bible is actually perfect instead of bunch of myths, legends and distorted history.

Ethelred
Ethelred
5 / 5 (6) Jun 03, 2011
Crank two
We have quantitative information that indicates the Sun and its planets were born in the death throes of a single precursor star.
We DO have evidence that the Solar System formed out of a gas cloud that included the debris of a super nova. There is NO evidence that the Sun was the source of the Supernova nor is there any evidence that ANY main sequence sun has a neutron star in it.

Indeed all the evidence is the contrary and it MAKES NO SENSE AT ALL since a neutron star with a large amount of hydrogen on it would cause that hydrogen to fuse right on the surface in a gamma ray burst. Besides which the smallest possible neutron star is more massive then the Sun.

Ethelred
Ethelred
5 / 5 (5) Jun 03, 2011
Crank three
Perhaps they have trouble seeing the clusters dissolve because they are not actually dissolving?
There are a lot of clusters that appear to have dispersed over time. The Pleiades for one example that is still fairly tight but not as tight since it still young.

accelerate the unrecognized new matter nucleation rate.
Unrecognized due the total lack of evidence for it and the magical nature of the concept that requires that matter appear out of nowhere without a top hat in sight.

This process is greatly accelerated in the galactic core,
Funny how we don't see any evidence for it.

Clusters grow from within.
Which doesn't fit the evidence nor is it even remotely possible without invoking magical creation of matter from nothing.

Why else are most globular clusters so old???
The Pleiades are VERY young. IF you were right THEN there should be no old clusters as they all should be spawning young stars. They aren't.>>
Ethelred
5 / 5 (5) Jun 03, 2011
When your theory MUST have things that do not exist then your theory is a crock.

Your theory REQUIRES
Matter being generated out of nothing.
Matter forming NEW suns where there is a high density of suns.

Globular clusters HAVE a high density and even you know they don't have young stars in the high density clusters. Only low density clusters like the Pleiades have young stars. This is exactly the opposite of your theory.

Ethelred
yyz
5 / 5 (4) Jun 03, 2011
"Perhaps they have trouble seeing the clusters dissolve because they are not actually dissolving?"

Astronomers have no trouble seeing clusters *dissolve*.
The Hipparchos mission observed proper motion and parallaxes for many nearby star clusters and indeed found evidence of their dissolution over time.

The Hyades cluster in Taurus was extensively studied by Hipparchos, producing maps of the internal motions of the cluster:

http://www.astro....eet.html

http://www.astr.u...nce.html
[note the cluster convergent point, though this is a perspective effect and does not represent the birthplace of the Hyades cluster]

And these Hipparchos observations of 20 nearby open clusters (esp. Fig 6): http://arxiv.org/...39v1.pdf

Also, check out the Ursa Major Moving Group: http://en.wikiped...ng_Group
Pyle
5 / 5 (2) Jun 04, 2011
Bravo. If only the three in question would actually be intellectually honest enough to read and understand your posts, Eth and yyz. Then this site would be a better place.

Great article too. If only I could earn a living by going back to school again...
CSharpner
5 / 5 (3) Jun 06, 2011
Kev: "as if it was the truth instead of a sim"

article: "This is how we *THINK* most of the stars..."

K: "I always marvel at the ability of people to find out things that happened in the past."

Such as EVIDENCE?.. There's a post with a prior timestamp with your name on it. I assume you posted it in the past. I see a ball rolling down a hill. I assume, in the recent past, it was further up the hill. I see the chared remains of a house, I assume a non-burnt house once stood there. I see smooth rock shaped like liquid that appears to be a frozen flow down a pointy mountain, I reasonably assume that liquid lava once flowed out the top of that pointy mountain (a "volcano"). If all measures of light show that its speed is constant and I see objects a billion light years away, I assume that the image I see was generated a billion years ago.

Answer me this: If the universe is only 6000 years old, why is it we see objects that are much further than 6000 light years away?
TheGhostofOtto1923
5 / 5 (3) Jun 07, 2011
For instance, just how exactly did they find out that all stars were born in star clusters?
Was this knowledge gained by some mathematical reconstruction or through actual observation of the birth and subsequent dispersion of stars to their current positions?
Kevin asks but he doesnt REALLY want to know.
Answer me this: If the universe is only 6000 years old, why is it we see objects that are much further than 6000 light years away?
For instance kevin would say that god dropped all the requisite radiation into the proper locations and sent it on its way, in order to make the universe LOOK like it was much older than it actually was.

But kevin wouldnt actually want to know WHY god would do such a deceptive thing. Why not? Who knows?