Tuesday, August 21, 2012

Globular Cluster Photo Series (Part 21): M19

Today I've got a picture of the globular cluster Messier 19. Much like M9 that I showcased last time, M19 is one of the globular clusters closest to the galactic core. It is about 28,000 light-years from Earth, and about 5,200 light-years from the core, narrowly beating M9 (at 5,500 light-years) for closest globular cluster to the core that I've showcased so far. M19 is the most elliptical globular cluster known (though it is only slightly noticeable in this picture), and is about 140 light-years across the long way. This is a good 50% bigger than M9, so since they are about the same distance away M19 looks a lot bigger on the sky at 17.0 arcminutes to M9's 12.0. (The full Moon for comparison is about 30 arcminutes across.)

Messier 19 in Ophiuchus.

Other than its great ellipticity (which may actually be a visual effect due to intervening dust extincting the light on one side), M19 is a fairly standard globular cluster with little to say about it despite its great size. It contains a rather small number of variable stars and was one of the earlier objects that Charles Messier observed. And other than that I really can't find much more interesting information about it. A hui hou!

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