Monday, May 7, 2012

Globular Cluster Photo Series (Part 18): M53

Today's picture (I'm slowly getting through the ones I have lying around) is the globular cluster Messier 53. M53 is a bit large as far as physical size goes, measuring about 220 light-years across, which gives it a visual diameter of 13.0 arcminutes at its estimated distance of a whopping 58,000 light-years from us. M53 is genuinely far out there, as it is also about 60,000 light-years from the galactic center, almost twice as far away from it as we are.

Messier 53 in Coma Berenices.

Like Messier 64 that I showcased yesterday, M53 is located in the constellation Coma Berenices, or Berenice's Hair, a small, faint constellation near Leo. According to legend, Queen Berenice II of Egypt had long, golden hair that she was quite proud of, and which she promised to sacrifice to Aphrodite if her husband King Ptolemy III Euergetes returned safely from his military expedition against the Seleucids. When he did so, she cut her hair and donated it to the temple, only for it to turn up missing the next morning. Thinking quickly, the court astronomer, a guy by the name of Conon of Samos, told the furious royal pair that the gods had apotheosized Berenice's hair into a constellation, indicating a misty patch of stars that have ever after borne that name. Interestingly, Ptolemy (the 2nd-century astronomer, not the king) did not include it in his definitive list of 48 recognized constellations, considering it part of Leo, though he did refer to is as “the lock [of hair]”. (He considered it to be the tuft of hair at the end of Leo's tail, which does make sense given its place in the sky.)

M53 contains a total of 47 RR Lyrae variable stars, a not inconsiderable number. Its stars also happen to be even lower in elements heavier than hydrogen and helium than most other globular clusters, which are already much lower than stars like the Sun. And other than that, I'm afraid there really isn't much more of interest to write about it tonight. A hui hou!

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