Star Formation in Open Clusters

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BDanielMayfield
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Star Formation in Open Clusters

Post by BDanielMayfield » Wed Dec 27, 2017 12:40 pm

When a new open cluster of stars starts to form, how rapid is the process? In other words, will all the members of the cluster all have the same age, or will the formation of stars sweep across the gas/dust cloud in a chain reaction?

Bruce
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Chris Peterson
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Re: Star Formation in Open Clusters

Post by Chris Peterson » Wed Dec 27, 2017 2:58 pm

BDanielMayfield wrote:When a new open cluster of stars starts to form, how rapid is the process? In other words, will all the members of the cluster all have the same age, or will the formation of stars sweep across the gas/dust cloud in a chain reaction?
As a rule, small star forming regions are short lived, just a few million years.
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BDanielMayfield
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Re: Star Formation in Open Clusters

Post by BDanielMayfield » Wed Dec 27, 2017 6:58 pm

Chris Peterson wrote:
BDanielMayfield wrote:When a new open cluster of stars starts to form, how rapid is the process? In other words, will all the members of the cluster all have the same age, or will the formation of stars sweep across the gas/dust cloud in a chain reaction?
As a rule, small star forming regions are short lived, just a few million years.
Let me use an analogy to better convey what I'm trying to ask. Picture a card table upon which dominoes are stood randomly, yet densely enough such that the fall of one domino is likely to trigger the fall of one or two of its neighbors. Consider two cases: (1) The table is given a forceful jolt, and all or almost all of the dominoes fall at nearly the same time. (2) The table is given a much weaker jolt, triggering the fall of only a few dominoes, which then cause chain reaction falls that in a short time result in the fall of most of them. Which case more closely reflects cluster star formation?
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Chris Peterson
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Re: Star Formation in Open Clusters

Post by Chris Peterson » Wed Dec 27, 2017 7:14 pm

BDanielMayfield wrote:
Chris Peterson wrote:
BDanielMayfield wrote:When a new open cluster of stars starts to form, how rapid is the process? In other words, will all the members of the cluster all have the same age, or will the formation of stars sweep across the gas/dust cloud in a chain reaction?
As a rule, small star forming regions are short lived, just a few million years.
Let me use an analogy to better convey what I'm trying to ask. Picture a card table upon which dominoes are stood randomly, yet densely enough such that the fall of one domino is likely to trigger the fall of one or two of its neighbors. Consider two cases: (1) The table is given a forceful jolt, and all or almost all of the dominoes fall at nearly the same time. (2) The table is given a much weaker jolt, triggering the fall of only a few dominoes, which then cause chain reaction falls that in a short time result in the fall of most of them. Which case more closely reflects cluster star formation?
I think you need to distinguish between different kinds of star forming regions. Some are created by shock fronts passing through regions rich in gas and dust. In those cases, the star formation is triggered by the shock front, sequenced by the movement of the front. But I think most open clusters form in small condensed regions of gas and dust. In that case, the stars simply form as material within the nebula collapses gravitationally. The nebula is short lived, so the stars are all about the same age, but their formation is largely independent of one another.
Chris

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BDanielMayfield
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Re: Star Formation in Open Clusters

Post by BDanielMayfield » Wed Dec 27, 2017 11:59 pm

Thank you Chris. Your comments help me weigh the reasonableness of an idea that I've been pondering for a while now. I was wondering if star formation might proceed in a chain reaction manner, with the formation of one star or system of stars triggering the formation of others. Perhaps this is an unreasonable hypothesis.

Bruce
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