Palomar 12 is a
globular cluster
A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting ...
in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The first constellati ...
Capricornus
Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat Horn (anatomy), horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is hal ...
, and is a member of the
Palomar Globular Clusters group.
First discovered on the
National Geographic Society – Palomar Observatory Sky Survey plates by
Robert George Harrington and
Fritz Zwicky,
it was initially catalogued as a globular cluster; however, Zwicky came to believe it was actually a nearby dwarf galaxy in the
Local Group. It is a relatively young cluster, being about 30% younger than most of the globular clusters in the
Milky Way
The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...
.
It is metal-rich with a
metallicity
In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...
of .
It has an average luminosity distribution of .
Based on
proper motion
Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...
studies, this cluster was first suspected in 2000 to have been captured from the
Sagittarius Dwarf Elliptical Galaxy (''SagDEG'') about 1.7
Ga ago.
It is now generally believed to have originated in that galaxy and is associated with the
Sagittarius Stream.
It is estimated to be 6.5 Gyr old.
See also
*
Messier 54
References
External links
Simbad reference data*
*
{{DEFAULTSORT:Palomar 12
Globular clusters
Sagittarius Dwarf Spheroidal Galaxy
Capricornus
?
•
Local Group