Palomar 14 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 ...

located 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 ...

Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Gr ...

. It is a member of the Palomar Globular Clusters group. Palomar 14 was discovered in 1958 by

Sidney van den Bergh Sidney Van den Bergh (born 20 May 1929) is a retired Dutch-Canadian astronomer. Van den Bergh showed an interest in science from an early age, learning to read with books on astronomy. In addition to being interested in astronomy, he also like ...

and

Halton Arp Halton Christian "Chip" Arp (March 21, 1927 – December 28, 2013) was an American astronomer. He is remembered for his 1966 book ''Atlas of Peculiar Galaxies'', which catalogued unusual-looking galaxies and presented their images. Arp was als ...

during inspection of the photographic plates from the

Palomar Sky Survey Palomar may refer to: Places * Any of several locations in San Diego County, California: ** Palomar Mountain *** Palomar Mountain, California, an unincorporated community ** Palomar College in San Marcos, California *** Palomar College Transit Ce ...

. This is a round, diffuse cluster located in the outer halo of 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 ...

galaxy. It is about 3–4 billion years younger than a typical galactic cluster. The metallicity of the cluster is e/H= −1.50, indicating a lower abundance of elements with mass greater than

helium Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...

compared to the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. The combined mass of the

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

s in the cluster is , and the combined mass of observed stars within the half-light radius is . (This is the inner radius of the cluster that emits half the total luminosity.) These mass estimates provide lower bounds for determining the total mass of the cluster. The median radial velocity of stars within the cluster is . Because of the cluster's location on the outer fringes of the Milky Way, it was used as a test case for modified Newtonian dynamics (

MOND Modified Newtonian dynamics (MOND) is a theory that proposes a modification of Newton's laws to account for observed properties of galaxies. Modifying Newton's law of gravity results in modified gravity, while modifying Newton's second law resul ...

). This is an alternative hypothesis to explain the galactic rotation problem.

References

{{Hercules (constellation) Globular clusters Astronomical objects discovered in 1958 Hercules (constellation)