What is the term for a collection of 105 to 106 old stars in a region 30 to 100 light-years in diameter?
What is the defining characteristic of stars within a cluster that are at the turnoff point?
They are just leaving the main sequence
They are just becoming white dwarfs
They are just entering the main sequence
They are about to explode in supernovae
What is the approximate age of the star cluster in the H-R diagram? (Hint: Main sequence stars of spectral types O and B have a core supply of hydrogen that is sufficient to last about 250 million years; types A and F, about 2 billion years; type G about 10 billion years; types K and M about 30 billion years. The apparent magnitude scale means that larger numbers are toward the bottom of the vertical axis.)