NGC 6712 | |
---|---|
Observation data (J2000 epoch) | |
Class | IX: [1] |
Constellation | Scutum |
Right ascension | 18h 53m 04.32s [2] |
Declination | –08° 42′ 21.5″ [2] |
Distance | 26.4 kly (8.1 kpc)< [3] |
Apparent magnitude (V) | +8.69 [2] |
Apparent dimensions (V) | 7.2' |
Physical characteristics | |
Mass | 9.4×104 [4] M☉ |
Metallicity | = –0.94 [5] dex |
Estimated age | 10.4 Gyr [5] |
Other designations | GCl 103, [2] GC 4441 |
NGC 6712 is a globular cluster that was probably discovered by Le Gentil on July 9, 1749 when investigating the Milky Way star cloud in Aquila. He described it as a "true nebula," in contrast to the open star cluster M11. Independently discovered by William Herschel on June 16, 1784 and cataloged as H I.47; he also first classified it as a round nebula. John Herschel was the first to describe it as a globular star cluster during his observations in the 1830s. The cluster appears to be about 12 billion years old and may have originally have been significantly more massive having undergone significant mass loss due to passes through the galactic disc. [3] For a globular cluster, NGC 6712 is somewhat metal-rich. [6]
NGC 6712 is home to a "black widow" pulsar named PSR J1853−0842A. Such systems involve an extremely rapidly rotating pulsar, accompanied by a low-mass star or brown dwarf. The high amounts of radiation emitted from the pulsar contributes to the evaporation of the low-mass companion, which has a mass between 0.018 and 0.036 solar masses. Although pulsars rotate more slowly with age, PSR J1853−0842A is accelerating, which would not be possible without it being within a globular cluster. [6]
Messier 5 or M5 is a globular cluster in the constellation Serpens. It was discovered by Gottfried Kirch in 1702.
Messier 3 is a globular cluster of stars in the northern constellation of Canes Venatici.
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.
Messier 15 or M15 is a globular cluster in the constellation Pegasus. It was discovered by Jean-Dominique Maraldi in 1746 and included in Charles Messier's catalogue of comet-like objects in 1764. At an estimated 12.5±1.3 billion years old, it is one of the oldest known globular clusters.
Messier 30 is a globular cluster of stars in the southeast of the southern constellation of Capricornus, at about the declination of the Sun when the latter is at December solstice. It was discovered by the French astronomer Charles Messier in 1764, who described it as a circular nebula without a star. In the New General Catalogue, compiled during the 1880s, it was described as a "remarkable globular, bright, large, slightly oval." It can be easily viewed with a pair of 10×50 binoculars, forming a patch of hazy light some 4 arcminutes wide that is slightly elongated along the east–west axis. With a larger instrument, individual stars can be resolved and the cluster will cover an angle of up to 12 arcminutes across graduating into a compressed core about one arcminute wide that has further star density within.
Messier 53 is a globular cluster in the Coma Berenices constellation. It was discovered by Johann Elert Bode in 1775. M53 is one of the more outlying globular clusters, being about 60,000 light-years (18.4 kpc) light-years away from the Galactic Center, and almost the same distance from the Solar System. The cluster has a core radius (rc) of 2.18 pc, a half-light radius (rh) of 5.84 pc, and a tidal radius (rtr) of 239.9 pc.
Messier 62 or M62, also known as NGC 6266, is a globular cluster of stars in the south of the equatorial constellation of Ophiuchus. It was discovered in 1771 by Charles Messier, then added to his catalogue eight years later.
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.
NGC 4833 is a globular cluster discovered by Abbe Lacaille during his 1751-1752 journey to South Africa, and catalogued in 1755. It was subsequently observed and catalogued by James Dunlop and Sir John Herschel whose instruments could resolve it into individual stars.
NGC 288 is a globular cluster in the constellation Sculptor. Its visual appearance was described by John Dreyer in 1888. It is located about 1.8° southeast of the galaxy NGC 253, 37′ north-northeast of the South Galactic Pole, 15′ south-southeast of a 9th magnitude star, and encompassed by a half-circular chain of stars that opens on its southwest side. It can be observed through binoculars. It is not very concentrated and has a well resolved, large 3′ dense core that is surrounded by a much more diffuse and irregular 9′ diameter ring. Peripheral members extend farther outward towards the south and especially southwest.
NGC 5986 is a globular cluster of stars in the southern constellation of Lupus, located at a distance of approximately 34 kilolight-years from the Sun. It was discovered by Scottish astronomer James Dunlop on May 10, 1826. John L. E. Dreyer described it as, "a remarkable object, a globular cluster, very bright, large, round, very gradually brighter middle, stars of 13th to 15th magnitude". Its prograde–retrograde orbit through the Milky Way galaxy is considered irregular and highly eccentric. It has a mean heliocentric radial velocity of +100 km/s. The galacto-centric distance is 17 kly (5.2 kpc), which puts it in the galaxy's inner halo.
NGC 6723 is a globular cluster in the constellation Sagittarius. Its magnitude is given as between 6 and 6.8, and its diameter is between 7 and 11 arcminutes. It is a class VII cluster with stars of magnitude 14 and dimmer. It is near the border of Sagittarius and Corona Australis.
NGC 6752 is a globular cluster in the constellation Pavo. It is the fourth-brightest globular cluster in the sky, after Omega Centauri, 47 Tucanae and Messier 22, respectively. It is best seen from June to October in the Southern Hemisphere.
NGC 6934 is a globular cluster of stars in the northern constellation of Delphinus, about 52 kilolight-years distant from the Sun. It was discovered by the German-born astronomer William Herschel on 24 September 1785. The cluster is following a highly eccentric orbit through the Milky Way along an orbital plane that is inclined by 73° to the galactic plane. It may share a common dynamic origin with NGC 5466. As of 2018, it has been poorly studied.
NGC 1851 is a relatively massive globular cluster located in the southern constellation of Columba. Astronomer John Dreyer described it as not very bright but very large, round, well resolved, and clearly consisting of stars. It is located 39.5 kilolight-years from the Sun, and 54.1 kilolight-years from the Galactic Center. The cluster is following a highly eccentric orbit through the galaxy, with an eccentricity of about 0.7.
NGC 1261 is a globular cluster of stars in the southern constellation of Horologium, first discovered by Scottish astronomer James Dunlop in 1826. The cluster is located at a distance of 53 kilolight-years from the Sun, and 59 kilolight-years from the Galactic Center. It is about 10.24 billion years old with 341,000 times the mass of the Sun. The cluster does not display the normal indications of core collapse, but evidence suggests it may have instead passed through a post core-collapse bounce state within the past two billion years. The central luminosity density is 2.22 L☉·pc−3, which is low for a globular cluster. Despite this, it has a Shapley–Sawyer Concentration Class of II, indicating a dense central concentration.
NGC 6352 is a globular cluster of stars in the southern constellation of Ara, located approximately 18.3 kly from the Sun. It was discovered by Scottish astronomer James Dunlop on May 14, 1826. The cluster has a Shapley–Sawyer Concentration Class of XI:. A telescope with a 15 cm (5.9 in) aperture is required to resolve the stars within this loose cluster.
NGC 6496 is a globular cluster which is in the direction of the Milky Way's galactic bulge based on observations collected with the WFPC2 on board the Hubble Space Telescope. NGC 6496 was originally believed to be a member of the disc system of the Galactic Center, but scientists questioned this classification. It was instead suggested that NGC 6496, together with two other clusters, NGC 6624 and NGC 6637, could be halo clusters with strongly inclined orbits. NGC 6496 lies in the Southern sky at RA=17:59:03.68 and Dec=-44:15:57.4.
NGC 4372 is a globular cluster in the southern constellation of Musca. It is southwest of γ Muscae and west of the southern end of the Dark Doodad Nebula, a 3° thin streak of black across a southern section of the great plane of the Milky Way.