Messier 80
Encyclopedia
Messier 80 is a globular cluster
in the constellation
Scorpius
. It was discovered by Charles Messier
in 1781.
M80 is located midway between α Scorpii (Antares
) and β Scorpii
in a field in the Milky Way that is rich in nebula
e. It can be viewed with modest amateur telescope
s as a mottled ball of light. With an apparent diameter of about 10' and at an estimated distance of 32,600 light-year
s, M80's spatial diameter is about 95 light-years. It contains several hundred thousand star
s, and is among the more densely populated globular clusters in the Milky Way Galaxy.
M80 contains a relatively large number of blue straggler
s, 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.
Globular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...
in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Scorpius
Scorpius
Scorpius, sometimes known as Scorpio, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is . It lies between Libra to the west and Sagittarius to the east...
. It was discovered by Charles Messier
Charles Messier
Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects"...
in 1781.
M80 is located midway between α Scorpii (Antares
Antares
Antares is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky . Along with Aldebaran, Spica, and Regulus it is one of the four brightest stars near the ecliptic...
) and β Scorpii
Beta Scorpii
Beta Scorpii is a star system in the constellation Scorpius. It has the traditional names Acrab, Akrab or Elacrab, all come from al-'Aqrab, the Scorpion, for the whole constellation, as well as Graffias, a name it shares with Xi Scorpii...
in a field in the Milky Way that is rich in nebula
Nebula
A nebula is an interstellar cloud of dust, hydrogen gas, helium gas and other ionized gases...
e. It can be viewed with modest amateur telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
s as a mottled ball of light. With an apparent diameter of about 10' and at an estimated distance of 32,600 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s, M80's spatial diameter is about 95 light-years. It contains several hundred thousand star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
s, and is among the more densely populated globular clusters in the Milky Way Galaxy.
M80 contains a relatively large number of blue straggler
Blue straggler
Blue stragglers are main sequence stars in open or globular clusters that are more luminous and bluer than stars at the main sequence turn-off point for the cluster. Blue stragglers were first discovered by Allan Sandage in 1953 while performing photometry of the stars in the globular cluster M3...
s, 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
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
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
Nova
A nova is a cataclysmic nuclear explosion in a star caused by the accretion of hydrogen on to the surface of a white dwarf star, which ignites and starts nuclear fusion in a runaway manner...
was discovered in M80 that attained a magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
of +7.0. The nova, variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
designation T Scorpii, reached an absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
of -8.5, briefly outshining the entire cluster.