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Sorry for the absolute begginer question here, but is our sun a part of some globular cluster? It is something related to Virgo supercluster?

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    $\begingroup$ It's possible that our sun is part of a multiple star system,e.g., en.wikipedia.org/wiki/Nemesis_(hypothetical_star) $\endgroup$ – Ben Crowell Jun 19 '18 at 18:48
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    $\begingroup$ We are in Local Interstellar Cloud but not a cluster ;-) $\endgroup$ – Tobias Piechowiak Jun 20 '18 at 15:28
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    $\begingroup$ SciShow Space episode from yesterday about this: youtube.com/watch?v=koaGqMF8sLI $\endgroup$ – Nick T Jun 20 '18 at 15:32
  • $\begingroup$ The comment above could be an answer (good short video). It's interesting that some open clusters could be potentially as old as the sun, $\endgroup$ – Jack R. Woods Jun 26 '18 at 0:21
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No the sun is not part of a cluster.

There are several types of clusters that we see in the sky. The most familiar is the "open cluster", like the Pleiades. These are a group of stars that formed together and have remained close.

As the stars drift apart they can become part of a "moving group", a collection of stars that don't appear to be a cluster, but since they share the same age and direction of motion we can tell they used to be a cluster. Many nearby stars are part of the Ursa Major moving group, but the sun is not one. It just happens to be in the same part of the Milky way. The sun was probably part of a cluster shortly after it formed (4.6 billion years ago) but that cluster has long ago broken up. We don't (yet) know of any other stars that seem to have come from the same cluster.

Globular clusters, like M13 and Omega Centauri, are larger and have many more stars tightly packed together. They are all rather distant, and the brightest look like slightly fuzzy stars (in fact Omega Centauri was originally thought to be a star).

Of course a galaxy is a group of 100 billion stars. We don't normally think of galaxies as a star cluster, because they are so much bigger and the stars in them don't form at the same time.

Then there are clusters of galaxies, the Virgo cluster is a cluster of galaxies, and the local group of galaxies is on the edge of this cluster. But the Virgo cluster is not a star cluster.

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    $\begingroup$ The June 2018 issue of Scientific American has an article about the early history of the Sun, talking about its galactic siblings. $\endgroup$ – Barmar Jun 19 '18 at 18:41
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    $\begingroup$ What does "formed together" mean? Came from the same nebula? If so, then referring to a galaxy as a star cluster would seem inappropriate, since the galaxy's stars don't really form from the same gas/dust cloud or anywhere near the same time frame. $\endgroup$ – jpmc26 Jun 19 '18 at 20:02
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    $\begingroup$ Yes that was badly worded. $\endgroup$ – James K Jun 20 '18 at 6:19
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It is very likely that most stars are born in clusters, ranging in size from 100 stars to a million or more (Lada & Lada 2003). It has been suggested (from indirect evidence) that our Sun was born in a cluster of somewhere between 1000 and 10,000 siblings (Adams 2010).

Unfortunately, most clusters do not survive beyond about 10 million years from their main star formation event. Various processes (gas expulsion, galactic tidal fields, dynamical interactions) pull these clusters apart and scatter their contents (i.e. the stars that were born in them) amongst the galactic field stars. The identity and location of our Sun's birth cluster and even the identity of its siblings can only be pieced together with a forensic examination of stellar kinematics and chemistry. That study has begun and is being greatly aided by massive spectroscopic surveys like Gaia-ESO, SDSS and LAMOST and with new astrometric/kinematic information from Gaia DR2. But at the moment we cannot be sure what cluster, if any, Sun was born in.

The Virgo supercluster refers to a cluster of galaxies and has nothing to do with the birth of stars in our Galaxy or of the Sun.

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    $\begingroup$ So, if the clusters dont survive more than a couple years, how could the M4 be dated as much than 12 billions years old? $\endgroup$ – Max Jun 19 '18 at 14:35
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    $\begingroup$ M4 is a globular cluster. As @JamesK has mentioned, they are rather different, and do indeed stay together much longer. $\endgroup$ – Steve Linton Jun 19 '18 at 15:16
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    $\begingroup$ @Max most clusters don't survive beyond ten million years. Indeed, it is easy to observe that most stars are not in clusters - so if they were all born in clusters then most clusters have dispersed. $\endgroup$ – Rob Jeffries Jun 19 '18 at 15:21
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    $\begingroup$ @Max - I think that's just the nature of the use of the word "most". Many, most, nearly all, etc... will act/happen in certain ways, but there will always be some, perhaps very very few, will be different, and sometimes, very very different. $\endgroup$ – Kevin Fegan Jun 20 '18 at 6:39
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    $\begingroup$ I'm not sure "unfortunately" is the right word here, given that (as far as we can tell from simulations and basic physics) close encounters between two stars (which happen more often in clusters, since stars are closer together there) tend to be... not so good for the stability of any planetary systems around them. A dense globular cluster might be an interesting place to live in, but there might not be much time for life to evolve there to appreciate it. $\endgroup$ – Ilmari Karonen Jun 20 '18 at 19:08

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