Centaurus in the context of IAU designated constellations


Centaurus in the context of IAU designated constellations

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⭐ Core Definition: Centaurus

Centaurus (/sɛnˈtɔːrəs, -ˈtɑːr-/ sen-TOR-əss, -⁠TAR-) is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. In Greek mythology, Centaurus represents a centaur; a creature that is half human, half horse (another constellation named after a centaur is one from the zodiac: Sagittarius). Notable stars include Alpha Centauri, the nearest star system to the Solar System, its neighbour in the sky Beta Centauri, and HR 5171, one of the largest stars yet discovered. The constellation also contains Omega Centauri, the brightest globular cluster as visible from Earth and the largest identified in the Milky Way, possibly a remnant of a dwarf galaxy.

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Centaurus in the context of Lupus (constellation)

Lupus is a constellation of the mid-Southern Sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations but was mostly considered an asterism associated with the nearby constellation Centaurus.

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Centaurus in the context of Proxima Centauri

Proxima Centauri, the nearest star to Earth after the Sun, is located 4.25 light-years (1.3 parsecs) away in the southern constellation of Centaurus. Discovered in 1915 by Robert Innes, it is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU (0.2 ly) from AB, which it orbits with a period of about 550,000 years. Its Latin name means the 'nearest star of Centaurus'.

Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass (M), and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh (14%) the diameter of the Sun. Although it has a very low average luminosity, Proxima Centauri is a flare star that randomly undergoes dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The internal mixing of its fuel by convection through its core and Proxima's relatively low energy-production rate, mean that it will be a main-sequence star for another four trillion years.

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Centaurus in the context of Centaurus A

Centaurus A (also known as NGC 5128 or Caldwell 77) is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type (lenticular galaxy or a giant elliptical galaxy) and distance (11–13 million light-years). It is the closest radio galaxy to Earth, as well as the closest BL Lac object, so its active galactic nucleus has been extensively studied by professional astronomers. The galaxy is also the fifth-brightest in the sky, making it an ideal amateur astronomy target. It is only visible from the southern hemisphere and low northern latitudes.

The center of the galaxy contains a supermassive black hole with a mass of 55 million solar masses, which ejects a relativistic jet that is responsible for emissions in the X-ray and radio wavelengths. By taking radio observations of the jet separated by a decade, astronomers have determined that the inner parts of the jet are moving at about half of the speed of light. X-rays are produced farther out as the jet collides with surrounding gases, resulting in the creation of highly energetic particles. The X-ray jets of Centaurus A are thousands of light-years long, while the radio jets are over a million light-years long.

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Centaurus in the context of Proxima Centauri b

Proxima Centauri b is an exoplanet orbiting within the habitable zone of the red dwarf star Proxima Centauri in the constellation Centaurus. It can also be referred to as Proxima b, or Alpha Centauri Cb. The host star is the closest star to the Sun, at a distance of about 4.2 light-years (1.3 parsecs) from Earth, and is part of the larger triple star system Alpha Centauri. Proxima b and Proxima d, along with the currently disputed Proxima c, are the closest known exoplanets to the Solar System.

Proxima Centauri b orbits its parent star at a distance of about 0.04848 AU (7.253 million km; 4.506 million mi) with an orbital period of approximately 11.2 Earth days. Its other properties are only poorly understood, but it is probably a terrestrial planet with a minimum mass of 1.06 M🜨 and a slightly larger radius than that of Earth. The planet orbits within the habitable zone of its parent star; but it is not known whether it has an atmosphere, which would impact the habitability probabilities. Proxima Centauri is a flare star with intense emission of electromagnetic radiation that could strip an atmosphere off the planet.

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Centaurus in the context of Proxima Centauri d

Proxima Centauri d (also called Proxima d) is a confirmed exoplanet orbiting the red dwarf star Proxima Centauri, the closest star to the Sun and part of the Alpha Centauri triple star system. Together with one or two other planets in the Proxima Centauri system, it is the closest known exoplanet to the Solar System, located approximately 4.2 light-years (1.3 parsecs; 40 trillion kilometres; 25 trillion miles) away in the constellation of Centaurus. The first signs of the exoplanet emerged as a weak 5.15-day signal in radial velocity data taken from the Very Large Telescope during a 2020 study on Proxima b's mass. This signal was formally proposed to be a candidate exoplanet by Faria et al. in a follow-up paper published in February 2022, and was independently confirmed in 2025.

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Centaurus in the context of Proxima Centauri c

Proxima Centauri c (also called Proxima c or Alpha Centauri Cc) is a controversial exoplanet candidate, claimed to be orbiting the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of a triple star system. It is located approximately 4.2 light-years (1.3 parsecs; 40 trillion kilometres; 25 trillion miles) from Earth in the constellation of Centaurus. If existing, this makes it, along with Proxima b and Proxima d, the closest known exoplanets to the Solar System.

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Centaurus in the context of Shapley Supercluster

The Shapley Supercluster or Shapley Concentration (SCl 124) is one of the largest concentrations of galaxies in the universe that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe. It appears as a striking overdensity in the distribution of galaxies in the constellation of Centaurus. Its center is located roughly 650 million light-years away (z=0.046).

Latest observations suggest Shapley Concentration may contain the Laniakea (which in turn contains the Local Group, including the Milky Way) along with a few other nearby superclusters that are moving towards the structure.

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Centaurus in the context of Omega Centauri

Omega Centauri (ω Cen, NGC 5139, or Caldwell 80) is a globular cluster in the constellation of Centaurus that was first identified as a non-stellar object by Edmond Halley in 1677. Located at a distance of 17,090 light-years (5,240 parsecs), it is the largest known globular cluster in the Milky Way at a diameter of roughly 150 light-years. It is estimated to contain approximately 10 million stars, with a total mass of 4 million solar masses, making it the most massive known globular cluster in the Milky Way.

Omega Centauri is very different from most other galactic globular clusters to the extent that it is thought to have originated as the core remnant of a disrupted dwarf galaxy. There is evidence of an intermediate-mass black hole in the dense core of this cluster, although this is disputed.

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Centaurus in the context of Great Rift (astronomy)

In astronomy, the Great Rift (sometimes called the Dark Rift or less commonly the Dark River) is a dark band caused by interstellar clouds of cosmic dust that significantly obscure (extinguish) the center and most radial sectors of the Milky Way galaxy from Earth's perspective.

In dark, clear night skies, the rift appears as clear as the bright bulge of stars around the Galactic Center does to the naked eye or binoculars. The rift is largely between the Solar System (which is close to the inner edge of the Orion Arm) and the next arm, inward, the Sagittarius Arm. The clouds are an obstruction to millions of the galaxy's stars detected at visible wavelengths, which compose a bright hazy band appearing 30° wide and arching through the night sky. The clouds within our radial sector of the galaxy span about 800–1,000 parsecs (2,600–3,300 ly) from Earth. The clouds are estimated to contain about 1 million solar masses of plasma and dust.

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Centaurus in the context of SN 185

SN 185 was a transient astronomical event observed in the year AD 185, likely a supernova. The transient occurred in the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA 14 43 Dec −62° 30′, in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han (後漢書), and might have been recorded in Roman literature. It remained visible in the night sky for eight months. This is believed to be the first supernova for which records exist.

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