M12, also cataloged as NGC 6218, is a globular cluster in Ophiuchus.
What It Is
M12, also cataloged as NGC 6218, is a globular cluster in Ophiuchus. It is a gravitationally bound sphere of old stars orbiting in the Milky Way's halo, but it is looser and less centrally concentrated than many globular clusters.
History
Charles Messier discovered M12 on May 30, 1764, one day after discovering nearby M10. Messier described it as a nebula without stars, but larger telescopes later resolved the glow into a rich cluster of individual stars.
Science Notes
- NASA lists M12 at about 16,000 light-years away with an apparent magnitude of 7.6.
- M12 lies in Ophiuchus near M10, making the pair a useful comparison between two nearby Messier globular clusters.
- Hubble and ground-based studies show that M12 has an unusually low number of low-mass stars for a globular cluster.
- ESA/Hubble notes that the missing low-mass stars were probably stripped away by the Milky Way's gravity during repeated passages through denser parts of the galaxy.
- Although globular clusters are ancient, M12's present-day structure records a long dynamical history, not just its original birth conditions.
- distance
- ~16,000 light-years
- apparentMagnitude
- +7.6
- diameter
- ~75 light-years
- constellation
- Ophiuchus
- objectType
- Globular cluster
- coordinates
- RA 16h 47m 14s, Dec -01 deg 56 min 52 sec
- bestObserved
- July from mid-northern latitudes
