Distance: 58,000 Light Years Telescope: 10” RC F8
Magnitude: 7.6 Camera: QSI 683
Size: 13 Arc Minutes Mount: AP 900
Cluster Type: Globular Class V Exposure: L 10×240 Bin 1, RGB 10×120 Bin2
Messier 53 is a class V globular cluster in the constellation Coma Berenices. At a distance of 58,000 light years its 13 arc minute diameter translates to about 220 light years in diameter. It is one of the furthest globular clusters from the galactic center at 60,000 light years. Like most globular clusters this cluster is populated with many older stars, RR Lyrae variables, and blue stragglers. All stars in globular clusters form at about the same time so they should be about the same age. The discovery of younger blue stars threw a wrench in to the conventional thinking. Why where there younger hotter stars in the cluster? One theory about blue stragglers is that they are stars that have been stripped of their outer layers through interaction with other stars leaving a hotter core. Another theory is that two stars have merged in to one giving the appearance of a younger hotter star. The RR Lyrae type variable stars are also a common feature in globular clusters and these variables typically have a short period. Named after the first discovered variable star of this type, RR Lyrae, these variable stars are about half the mass of our sun, older than our sun, and also hotter than our sun. The variation in brightness is due to the increase and decrease in size of the star as its outer layers pulsate. The variable star will be brightest at its smallest size and dimmest at its largest size. These periods can be timed with great accuracy.
[SEDS, Universe Today, Wikipedia]