Messier 12
Encyclopedia
Messier 12 or M 12 is a globular cluster
in the constellation
of Ophiuchus
. It was discovered by Charles Messier
on May 30, 1764.
Located roughly 3° in the sky from the cluster M10
, M12 is about 16,000 light-year
s from Earth and has a spatial diameter of about 75 light-years. The brightest stars of M12 are of 12th magnitude
. It is rather loosely packed for a globular and was once thought to be a tightly concentrated open cluster
. Thirteen variable star
s have been recorded in this cluster.
A study published in 2006 concluded that this cluster has an unusually low number of low mass stars. The authors surmise that they were stripped from the cluster by the gravitational influence of the Milky Way
.
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....
of Ophiuchus
Ophiuchus
Ophiuchus is a large constellation located around the celestial equator. Its name is from the Greek "serpent-bearer", and it is commonly represented as a man grasping the snake that is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century...
. 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"...
on May 30, 1764.
Located roughly 3° in the sky from the cluster M10
Messier 10
Messier 10 or M10 is a globular cluster in the constellation of Ophiuchus.The object was discovered by Charles Messier on May 29, 1764, who cataloged it as number 10 in his list...
, M12 is about 16,000 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 from Earth and has a spatial diameter of about 75 light-years. The brightest stars of M12 are of 12th 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...
. It is rather loosely packed for a globular and was once thought to be a tightly concentrated open cluster
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist...
. Thirteen 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...
s have been recorded in this cluster.
A study published in 2006 concluded that this cluster has an unusually low number of low mass stars. The authors surmise that they were stripped from the cluster by the gravitational influence of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
.