Messier 80

Messier 80
A Hubble Space Telescope (HST) image of M80. Credit: HST/NASA/ESA.
Observation data (J2000 epoch)
Class	II
Constellation	Scorpius
Right ascension	16h 17m 02.41s
Declination	–22° 58′ 33.9″
Distance	32.6 kly (10.0 kpc)
Apparent magnitude (V)	+7.87
Apparent dimensions (V)	10′.0
Physical characteristics
Mass	7005501999999999999♠5.02×105 M☉
Radius	48 ly
Metallicity	${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = –1.47dex
Estimated age	12.54
Other designations	M80, NGC 6093, GCl 39
See also: Globular cluster, List of globular clusters

Messier 80 (also known as M80 or NGC 6093) is a globular cluster in the constellation Scorpius. It was discovered by Charles Messier in 1781.

The star cluster is located midway between α Scorpii (Antares) and β Scorpii in a field in the Milky Way that is rich in nebulae. It can be viewed with modest amateur telescopes as a mottled ball of light. With an apparent diameter of about 10' and at an estimated distance of 32,600 light-years, M80's spatial diameter is about 95 light-years. It contains several hundred thousand stars, and is among the more densely populated globular clusters in the Milky Way.

It contains a relatively large number of blue stragglers, stars that appear to be much younger than the cluster itself. It is thought these stars have lost part of their outer layers due to close encounters with other cluster members or perhaps the result of collisions between stars in the dense cluster. Images from the Hubble Space Telescope have shown districts of very high blue straggler densities, suggesting that the center of the cluster is likely to have a very high capture and collision rate.

On May 21, 1860, a nova was discovered in M80 that attained a magnitude of +7.0. The nova, variable star designation T Scorpii, reached an absolute magnitude of −8.5, briefly outshining the entire cluster.

Coordinates: 16^h 17^m 02.51^s, −22° 58′ 30.4″