STAR CLUSTERS

STAR CLUSTERS

b) Galaxy clusters are distributed over the entire circumference of the Milky Way; globular clusters are almost completely absent in the northern celestial hemisphere.

c) Galaxy clusters consist of tens or hundreds of stars, rarely thousands; globular systems contain tens or hundreds of thousands of stars.

d) The mean radial velocity of galaxy clusters is known to be low, rarely exceeding forty kilometers per second: globular clusters move on average with a radial velocity of more than one hundred kilometers per second.

e) Galaxy clusters, at least two or three hundred cataloged, almost all located within four thousand light-years from the Sun. All globular clusters are further than ten thousand light-years, and at least a third of them are further than one hundred light-years. thousand

f) Galaxy clusters are irregular in shape, of different sizes, and contain a different number of stars: globular clusters, with a few exceptions, seem to be of comparable size and of comparable general brightness, leading one to think that the number of stars in them is approximately the same.