Is our sun part of a star cluster?

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Discussion Overview

The discussion centers on whether the Sun is part of a star cluster, specifically addressing the classification of the Sun in relation to nearby stars like Alpha Centauri and Barnard's Star. Participants explore the implications of star density, gravitational binding, and the historical context of the Sun's formation.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants assert that the Sun is not part of any gravitationally-bound cluster, despite having nearby stars.
  • One participant suggests that the Sun may have once been part of an open cluster but has since dispersed over time due to gravitational interactions.
  • Another participant provides a comparison of star densities in clusters versus the density near the Sun, indicating a significant difference that supports the idea of non-membership in a cluster.
  • There is a mention of the dispersion rate of mid-sized stars, which could affect the distances between potential cluster members.
  • One participant explicitly states that even if the Sun were part of an open cluster, Barnard's Star would not be a member.

Areas of Agreement / Disagreement

Participants generally disagree on the classification of the Sun in relation to star clusters, with multiple competing views presented regarding its historical membership and current status.

Contextual Notes

Participants reference the half-life of open clusters and the implications of star density, but there are unresolved assumptions regarding the definitions of cluster membership and the historical context of the Sun's formation.

lilythmagebor
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Because I was curious about this, I read here that, "Our own Sun is part of an open cluster than includes other nearby stars such as Alpha Centauri and Barnard's star."
However, I cannot find any other pages claiming this, and the wikipedia entry on star clusters does not mention us being within a cluster, which I would think would be a rather important thing to mention.
Can anyone give me a definitive 'yes' or 'no' on this one?
 
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The Sun is not part of any cluster. Are there stars that are nearby (in galactic terms)? Yes. Are they part of of a gravitationally-bound group? Nope.

If you have access to a small telescope, look at the double cluster. That's what open clusters look like.
 
I think your link is supposed to say that the sun USED to be part of an open cluster. By its own words it says that the stars will disperse due to interactions with other objects over time.
 
"Typical star densities in the centre of a cluster are about 1.5 stars per cubic light year (the stellar density near the sun is about 0.003 star per cubic light year)."

http://en.wikipedia.org/wiki/Open_cluster#Morphology_and_classification

Open clusters tend to be young because gravitational interactions disperse its members over time. According to the same article, the half life of open clusters is 150-800 million years. The Sun is 4.6 billion years old, so if it once belonged to an open cluster, that cluster had plenty of time to dissipate.
 
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IIRC, the dispersion rate of 'mid-sized' stars such as our Sun's G8 is important because it would make the difference between sibs being 40~~50 LY apart, so fairly easy to spot, and 100~~200 LY apart, so statistically dubious...

With luck, searching for 'metal rich' stars in our galactic arm may find some plausible candidates...
 
To add to the mix, even if the sun were part of an open cluster, there's no way Barnard's Star would be a member of it.
 

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