Kim 2 | |
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Observation data (J2000 epoch) | |
Constellation | Indus |
Right ascension | 21h 08m 49.970s [1] |
Declination | −51° 09′ 48.60″ [1] |
Distance | 104.7±4.1 kpc [1] |
Apparent dimensions (V) | 0.28′ (half-mass diameter) |
Physical characteristics | |
Absolute magnitude | −1.5±0.5 [1] |
Mass | 600 M☉ |
Metallicity | = −1.0+0.18 −0.21 [1] dex |
Estimated age | 11.5+2 −3.5 Gyr |
Other designations | Indus I [2] |
Kim 2, also known as Indus I, [2] is a distant globular cluster in the constellation of Indus. It was discovered by Dongwon Kim of the Stromlo Milky Way Satellite Survey run by the Australian National University using the SkyMapper telescope images. Since it was so faint it needed examination by more powerful telescopes like those at the Cerro Tololo Inter-American Observatory. It is possibly the core of a dwarf galaxy that has been swallowed up by the Milky Way. This cluster is unusual in that it has far fewer stars than most globular clusters. [3] Kim 2 is more enriched in metals than most other outer globular clusters, suggesting that it formed later. [4]
The cluster is 105 kpc away from Earth. The half light radius is 12.8 pc. The metallicity [Fe/H] is about −1.0. [1]
A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and the distinction between the two is not always clear. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".
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Messier 12 or M 12 is a globular cluster in the constellation of Ophiuchus. It was discovered by the French astronomer Charles Messier on May 30, 1764, who described it as a "nebula without stars". In dark conditions this cluster can be faintly seen with a pair of binoculars. Resolving the stellar components requires a telescope with an aperture of 8 in (20 cm) or greater. In a 10 in (25 cm) scope, the granular core shows a diameter of 3′ (arcminutes) surrounded by a 10′ halo of stars.
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Messier 22 or M22, also known as NGC 6656, is an elliptical globular cluster of stars in the constellation Sagittarius, near the Galactic bulge region. It is one of the brightest globulars visible in the night sky. The brightest stars are 11th magnitude, with hundreds of stars bright enough to resolve with an 8" telescope. It is just south of the sun's position in mid-December, and northwest of Lambda Sagittarii, the northernmost star of the "Teapot" asterism.
Messier 28 or M28, also known as NGC 6626, is a globular cluster of stars in the center-west of Sagittarius. It was discovered by French astronomer Charles Messier in 1764. He briefly described it as a "nebula containing no star... round, seen with difficulty in 31⁄2-foot telescope; Diam 2′."
47 Tucanae or 47 Tuc is a globular cluster located in the constellation Tucana. It is about 4.45 ± 0.01 kpc (15,000 ± 33 ly) away from Earth, and 120 light years in diameter. 47 Tuc can be seen with the naked eye, with an apparent magnitude of 4.1. It appears about 44 arcminutes across including its far outreaches. Due to its far southern location, 18° from the south celestial pole, it was not catalogued by European astronomers until the 1750s, when the cluster was first identified by Nicolas-Louis de Lacaille from South Africa.
NGC 2419 is a globular cluster in the constellation Lynx. It was discovered by William Herschel on December 31, 1788. NGC 2419 is at a distance of about 300,000 light years from the Solar System and at the same distance from the Galactic Center.
The Milky Way has several smaller galaxies gravitationally bound to it, as part of the Milky Way subgroup, which is part of the local galaxy cluster, the Local Group.
NGC 3201 is a low galactic latitude globular cluster in the southern constellation of Vela. It has a very low central concentration of stars. This cluster was discovered by James Dunlop on May 28, 1826 and listed in his 1827 catalogue. He described it as "a pretty large pretty bright round nebula, 4′ or 5′ diameter, very gradually condensed towards the centre, easily resolved into stars; the figure is rather irregular, and the stars are considerably scattered on the south".
Arp-Madore 1 is a globular cluster visible in the constellation Horologium, located 123.3 kiloparsecs away from Earth. It is one of the most distant known globular clusters of the Milky Way galaxy's halo; its distance gives it interest as a test case for gravitational theories. It is named after Halton Arp and Barry F. Madore, who identified it as a distant globular cluster in 1979, using the UK Schmidt Telescope, after previous researchers at the European Southern Observatory had observed its existence but not its classification.
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