Simple view of gravity does not fully explain distribution of stars in crowded clusters

Feb 20, 2013
Hubble Space Telescope image of the young star cluster NGC 1818 in the Large Magellanic Cloud. KIAA researchers found to their surprise an increasing fraction of binary systems as they looked at increasingly larger distances from the cluster center, as illustrated graphically in the inset. Credit: Peking University

(Phys.org)—Gravity remains the dominant force on large astronomical scales, but when it comes to stars in young star clusters the dynamics in these crowded environments cannot be simply explained by the pull of gravity.

After analyzing images of star cluster NGC 1818 in the , a of the Milky Way, researchers at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University in Beijing found more binary star systems toward the periphery of cluster than in the center – the opposite of what they expected. The surprising distribution of binaries is thought to result from complex interactions among within young clusters.

The team's finding will be published in the March 1 print issue of the , and is now online.

In the dynamic environment of a star cluster, high-mass stars are thought to gravitate toward the center of a cluster when they give a 'kick' to lower-mass stars and lose energy, explained KIAA Prof. Richard de Grijs, who led the study. This leads them to sink to the cluster center, while the lower-mass stars gain energy and might move to orbits at greater distances from the cluster core. Astronomers call this process "mass segregation."

However, when the Kavli researchers looked closely at within NGC 1818, they found a much more complex picture.

Most stars in clusters actually form in pairs, called "binary stars," which initially are located so close to one another that they interact, resulting in the destruction of some . Other binaries, meanwhile, swap partners. Astronomers had expected that the same process that leads a cluster's most massive stars to gravitate toward the center would also apply to binaries. This is because together, the stars that make up binaries have more mass on average than a single star.

When the astronomers discovered that there were more binaries the farther from the core they observed, they were initially baffled by this unexpected result. They concluded that so-called "soft" binary systems, in which the two stars orbit each other at rather large distances, are destroyed due to close encounters with other stars near the cluster's center. Meanwhile, "hard" binaries, in which the two stars one another at much shorter distances, survive close encounters with other stars much better, all throughout a cluster. This is why more binaries were seen farther out than close in.

Mapping the radial distribution of binary systems in dense had never been done before for clusters as young as NGC 1818, which is thought to be 15-30 million years old. This is difficult to do in any case, because there are no young clusters nearby in our own Milky Way galaxy. The new result provides new insights into theoretically predicted processes that govern the evolution of star clusters.

"The extremely dynamic interactions among stars in clusters complicates our understanding of gravity," team member Chengyuan Li said. "One needs to investigate the entire physical environment to fully understand what's happening in that environment. Things are usually more complex than they appear."

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More information: iopscience.iop.org/0004-637X/765/1/4

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vacuum-mechanics
1 / 5 (12) Feb 20, 2013
(Phys.org)—Gravity remains the dominant force on large astronomical scales, but when it comes to stars in young star clusters the dynamics in these crowded environments cannot be simply explained by the pull of gravity.

It is interesting that now both Newton gravity and Einstein gravity still could not explain what the cause of gravity is or how it works! Understand the mechanism of gravity as below may help to solve the problem….
http://www.vacuum...=7〈=en
Q-Star
4.3 / 5 (12) Feb 20, 2013
It is interesting that now both Newton gravity and Einstein gravity still could not explain what the cause of gravity is or how it works!


I think that ya have that doubly wrong,,,, Newton and Einstein never posited a "cause". They never attempted to explain the "cause",,,, only the way it works. So they did not fail.

The "how" they posited has been confirmed many times over through the centuries. And within the bounds their theories were constrained by when posited,,, they have never failed a test.

So yes they did explain the "how", and did it better than any other has to date.
cantdrive85
1.7 / 5 (11) Feb 20, 2013
Newton and Einstein never posited a "cause".

"But hitherto I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses." Isaac Newton

they have never failed a test

Well, not really, otherwise the invention of dark matter would be moot. Not to mention this article. Or this one;
http://phys.org/n...tes.html
There are many other situations where gravity doesn't quite fit the bill, but who cares about facts, certainly not you.
Q-Star
4 / 5 (8) Feb 20, 2013
Newton and Einstein never posited a "cause".

"But hitherto I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses." Isaac Newton


Yep that's exactly what I said.

they have never failed a test

Well, not really, otherwise the invention of dark matter would be moot.

Not to mention this article. Or this one;
http://phys.org/n...tes.html


Pssst, that article doesn't not point out any failure of Newton's or Einstein's theories,,, if anything, it supports it, somewhat, but then you thought that article was all bunko science anyway.

There are many other situations where gravity doesn't quite fit the bill,


There is nothing that fits the bill as well without suspending the rule that physics here are the same as physics there. PC requires turning on or off thermodynamics, fluid dynamics, electrodynamics, nuclear physics etc, for every situation.
cantdrive85
1.4 / 5 (10) Feb 20, 2013
PC requires turning on or off thermodynamics, fluid dynamics, electrodynamics, nuclear physics etc, for every situation.


This is an absolutely false statement, typical strawman from the master. A factual statement would be something along the lines of, "the 99.999% of the Universe which consists of plasma only behaves like plasma when we want it to, and never when it suggests any part of the standard theory is incorrect."

BTW, the electrodynamics of plasma is entirely ignored by the standard theory, this was the main reason that led Alfven to come up with PC. It's quite ironic you chose to include it.

Tuxford
1 / 5 (7) Feb 20, 2013
If binaries grow by birth of the daughter star from the parent star, and the parent stars grow from within over time through new matter generation deep inside the cores, and the massive core star periodically erupts giving birth to the parent stars who then migrate to the perimeter of the cluster, then one would expect more binaries in the periphery than near the center.

These clusters are simply baby galactic cores.

This is more support for LaViolette's SubQuantum Kinectics.

Hate it. Sure. But time and again the model fits the unexpected observations. Go figure...
verkle
1 / 5 (5) Feb 20, 2013
Add to this the complexity that star clusters are not flat like the solar system, but rather spherical, with stars moving in 3D.

Such a system really is not stable over millions of years, and stars should continously be thrown out of the system. No model exists yet to adequately explain this behavior.

Q-Star
4.5 / 5 (8) Feb 20, 2013
PC requires turning on or off thermodynamics, fluid dynamics, electrodynamics, nuclear physics etc, for every situation.


A factual statement would be something along the lines of, "the 99.999% of the Universe which consists of plasma only behaves like plasma when we want it to, and never when it suggests any part of the standard theory is incorrect."

BTW, the electrodynamics of plasma is entirely ignored by the standard theory,


You must NOT know much about the "standard theory" if you would say that.

That shows just how little you know of this thing you want to know so much about. All you do is repeat the same tired mantra without knowing the science you proclaim.

"yet it moves", either school me, or entertain me. If you can't teach it you must not know it very well. "yet it moves", tell me how it moves, now I will sit in the back listen to you explain.

Remember, all phenomena together, no suspending of the forces case by case.
Q-Star
4.3 / 5 (6) Feb 20, 2013
Add to this the complexity that star clusters are not flat like the solar system, but rather spherical, with stars moving in 3D.

No model exists yet to adequately explain this behavior.


Finally you say something that I almost agree with,,,,,, anyone who has learned to do a three body solution without the aid of a computer, which we did as undergraduate astrophysics students, can tell you how impossible it would be to perfectly model a system of 10,000 bodies. Each with their own mass and orbitals. At a distance of a kilo-parsec to several hundred kilo-parsecs.

Even with supercomputers and a lot time, the best you can hope for is a close approximation. That is one of my pet peeves with the lay public and science, they expect that everything has an absolute and exact number to report.
Q-Star
4.4 / 5 (7) Feb 20, 2013
@ cantdrive,,,

Let's put something to a test. A fair test. You repeatedly say that the astrophysics community completely discounts and is uninformed in matters of plasma, and electromagnets, and electrodynamics.

You posit as evidence something that ONE man said to a group of electricians & electrical engineers. THIRTY-ODD YEARS AGO.

I posit that this is entirely false. I further posit that when you rail against the "standard model" you don't know the so-called "standard model".

Please pick out ANY of the STANDARD texts currently in use at any institution that awards degrees in Astronomy/Astrophysics that supports your claims of neglect.

I probably, either, use that text, or if it is a STANDARD text I will very, very probably have it sitting right here in front of me. (We are given most new texts and new editions to evaluate, freebies & perks ya know.)

I'll use that textbook to put you to the lie. All I require is that it be a common, mainstream text in current use.
Q-Star
4.3 / 5 (6) Feb 20, 2013
@ cantdrive,,,,

In case I wasn't clear, a text in Astrophysics that you think proves that plasma and electromagnetism is neglecting to cover.

You charge neglect of the subject matter,,,,,

I charge that you are either repeating something you don't know the truth of. Or just making a baseless accusation to further your point of view.
cantdrive85
1 / 5 (4) Feb 20, 2013
Using any of the astrophysical textbooks you have at your disposal, please define and explain where we should find a double layer, and an exploding double layer, this is a very common attribute of plasma and should be readily available if I'm incorrect.

I would also direct you to this paper by professor of electrical engineering Don Scott [Electric Currents Key to Magnetic Phenomena- http://electric-c...OAAJ.pdf ] and explain to me how you can consider magnetic fields without the presence of electric currents/fields.
dav_daddy
1.7 / 5 (6) Feb 20, 2013
@ cantdrive,,,,

In case I wasn't clear, a text in Astrophysics that you think proves that plasma and electromagnetism is neglecting to cover.


Laying odds on how this one works its self out:

2 to 1 The reply is an insult and/or accusation of conspiracy
5 to 1 His question will only be valid if you suspend 1 of the laws of physics
7 to 1 His question will only be valid if 3 or more laws are suspended
5 to 3 His question will contain 1 or more that have no scientific definition
12 to 1 This challenge is totally ignored
50 to 1 A well thought out question is asked
6 to 1 Another of these pinheads will come in flaming and this will degenerate into a flame war.
1 to 1 No matter how much evidence and data are presented these fairy tales will still be clung to and inflicted on the rest of us hereinafter.

typicalguy
5 / 5 (1) Feb 20, 2013
Q star, you may be interested in this: http://www.physic...t=670299
Evidently there will be an online talk about this. These guys may have come up with a way to unify gravity with the weak nuclear force. So call "gravi-weak".
Sonhouse
not rated yet Feb 21, 2013
Add to this the complexity that star clusters are not flat like the solar system, but rather spherical, with stars moving in 3D.

No model exists yet to adequately explain this behavior.


Finally you say something that I almost agree with,,,,,, anyone who has learned to do a three body solution without the aid of a computer, which we did as undergraduate astrophysics students, can tell you how impossible it would be to perfectly model a system of 10,000 bodies. Each with their own mass and orbitals. At a distance of a kilo-parsec to several hundred kilo-parsecs.

Even with supercomputers and a lot time, the best you can hope for is a close approximation. That is one of my pet peeves with the lay public and science, they expect that everything has an absolute and exact number to report.

Question: As to multi-body problems. Could quantum computers do the job, I mean theoretically, considering they don't exist yet.
rubberman
1 / 5 (1) Feb 21, 2013


Even with supercomputers and a lot time, the best you can hope for is a close approximation. That is one of my pet peeves with the lay public and science, they expect that everything has an absolute and exact number to report.

Question: As to multi-body problems. Could quantum computers do the job, I mean theoretically, considering they don't exist yet.

They may be able to do the job, the problem, as Q pointed out is the lack of detailed data on what we would be trying to model. We still have more to learn about the sun than we actually know, let alone the properties of each star in a globular cluster many light years away.
Q-Star
3.7 / 5 (3) Feb 21, 2013
Using any of the astrophysical textbooks you have at your disposal, please define and explain where we should find a double layer, and an exploding double layer, this is a very common attribute of plasma and should be readily available if I'm incorrect.

I would also direct you to this paper by professor of electrical engineering Don Scott [Electric Currents Key to Magnetic Phenomena- http://electric-c...OAAJ.pdf ] and explain to me how you can consider magnetic fields without the presence of electric currents/fields.


Electrical engineers are not astrophysicists. Be that as it may,,,,

I'm still waiting for you to point to a standard text in astrophysics that has lead YOU to believe that the study of plasmas and electromagnetic is neglected and "completely ignored" in astrophysics.

Point to the text which you used to base YOUR understanding of the so-called "standard model" to such a degree that YOU can so confidently rail against it.

I bet you can't.
Shootist
1 / 5 (2) Feb 24, 2013
If binaries grow by birth of the daughter star from the parent star, and the parent stars grow from within over time through new matter generation deep inside the cores,


Oliver K Manuel? Is that You?