Messier 80

Messier 80 (also known as M80 or NGC 6093) is a globular cluster located approximately 32,600 light-years (10,000 pc) from Earth in the constellation Scorpius. Discovered by Charles Messier in 1781, it is one of the densest globular clusters in the Milky Way, containing several hundred thousand stars within a spatial diameter of about 95 light-years.^[9]

Messier 80
A Hubble Space Telescope (HST) image of M80
Observation data (J2000 epoch)
Class	II[1]
Constellation	Scorpius
Right ascension	16h 17m 02.41s[2]
Declination	–22° 58′ 33.9″[2]
Distance	32.6 kly (10.0 kpc)[3]
Apparent magnitude (V)	7.3[4]
Apparent dimensions (V)	10.0′
Physical characteristics
Mass	5.02×105[5] M☉
Radius	48 ly
Metallicity	${\displaystyle {\begin{smallmatrix}\left[{\ce {Fe}}/{\ce {H}}\right]\end{smallmatrix}}}$ = –1.47[6] dex
Estimated age	13.5 ± 1.0 Gyr[7]
Other designations	M80, NGC 6093, GCl 39[8]
See also: Globular cluster, List of globular clusters

The cluster is situated in the Galactic halo, more than twice as distant as the Galactic Center, and lies midway between the stars α Scorpii (Antares) and β Scorpii in a region rich with nebulæ. With an apparent angular diameter of 10 arcminutes, it can be observed from locations below the 67th parallel north using modest amateur telescopes, where it appears as a mottled ball of light under low light pollution conditions.^[9]

Messier 80 is notable for its high population of blue stragglers, stars that appear younger than the cluster itself. Hubble Space Telescope observations reveal these stars are concentrated in distinct regions, suggesting frequent stellar interactions or collisions in the cluster's dense core.^[9] On May 21, 1860, the cluster hosted the nova T Scorpii, which briefly outshone the entire cluster with an absolute magnitude of −8.5 and reached an apparent magnitude of +7.0, visible through telescopes and binoculars.^[9]

Gallery

• 
  M80 is on the far-right edge of this image of Rho Ophiuchi cloud complex toward the top
• 
  Map showing the location of M80

See also

• List of Messier objects