They typically contain relatively large numbers of RR Lyrae stars, and their HR diagrams typically have short main sequences and prominent horizontal branches, indicating very old stars.
The study of these objects in the 1930s led to a precise determination of the sun's position in the Milky Way. M87 is believed to contain as many as 15 thousand of them, and exotic star types such as blue stragglers and millisecond pulsars are more common in them. Structurally, these objects are similar to the bugles in spiral galaxies, but are confined to only a few parsecs. They typically contain relatively large numbers of RR Lyrae stars, and their HR diagrams typically have short main sequences and prominent horizontal branches, indicating very old stars. FTP, what are these dense collections of stars held together by gravity?
The study of these objects in the 1930s led to a precise determination of the sun's position in the Milky Way.
globular clusters