Messier 12

M12, NGC 6218

Messier 12

Distance: 16,000 Light Years                      Telescope: 10” RC F8
Magnitude: 6.7                                                 Camera: QSI 683
Size: 16 Arc Minutes                                       Mount: AP 900
Cluster Type: Globular Class IX                 Exposure: L 7×240 Bin 1, RGB 7×120 Bin2

Messier 12 is a globular cluster in the constellation Ophiuchus. Like all globular clusters, M12 is very old at 13 billion years. M12 contains about 200,000 stars but what is unusual about M12 is that it missing a lot of the low mass stars typically found in globular clusters. One explanation is the galactic orbit of M12 takes it closer to the galactic core than many other globular clusters. As M12 moves through the core area the lower mass stars are stripped away by the massive gravitational pull of the dense core area. This could explain the Class IX rating given to this cluster. The Class IX rating means that M12 has a loosely concentrated core area.

M12 is home to variable stars, blues stragglers, and red giants. What is unusual is that M12 only has 13 variable stars which is a small quantity for globular clusters. M12 is also populated with blue stragglers which are younger hotter stars that have formed as a result of interaction with other older stars. The red giants are large cool stars that are at the end of their lifespan.

[Science Blogs, ESO/ESA, SEDS]

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