Starship Asterisk*

[c][attachment=0]NGC_1651_hst_05972_58_wfpc2_R814_G_B555_05475_0r_555[1].png[/attachment][/c]

A close look at the night sky reveals that stars don’t like to be alone; instead, they congregate in clusters, in some cases containing as many as several million stars. Until recently, the oldest of these populous star clusters were considered well understood, with the stars in a single group having formed at different times, over periods of more than 300 million years. Yet new research published online today in the journal Nature suggests that the star formation in these clusters is more complex.

Using data from the Hubble Space Telescope, a team of researchers at the Kavli Institute for Astronomy and Astrophysics (KIAA) at Peking University and the Chinese Academy of Science’s National Astronomical Observatories in Beijing have found that, in large middle-aged clusters at least, all stars appear to be of about the same age. ...

Previous observations of massive star clusters revealed a relatively large amount of variation in temperature from stars reaching the end of their core hydrogen supply, suggesting that the stars within the clusters varied in age by as much as 300 million years or more. ...

The research suggests that, for middle-aged clusters at least, today’s conventional wisdom may be wrong and it might be common for all stars in a single cluster to be of approximately the same age. ...

• Nature 516(7531) 367 (18 Dec 2014) DOI: 10.1038/nature13969

MargaritaMc wrote:My initial confusion was clarified once I realised that this is talking about globular clusters, not open clusters.

M

... stars don’t like to be alone; instead, they congregate in clusters ...

http://astrobites.org/2014/12/21/the-cu ... -sequence/
by Suk Sien Tie
Background
Classes we take in undergraduate astronomy tell us that stars in a globular cluster form at the same time from the collapse of a molecular cloud. Besides luminosity difference arising from different mass distribution among the stars (with more luminous stars having larger masses), they all have similar chemical composition and are located at the same distance. Most importantly, they have roughly the same age. We call this type of star cluster “co-eval”, “single-generation”, or “simple” stellar population. However, we have been discovering recently that is not the case at all. Recent trend has been moving toward multiple-generation stellar populations in globular clusters...