Roughly the size of Jupiter, it completes an orbit around its star every three days. [62] Another galaxy cluster, Abell 2162, is a member of the Hercules Superclusters. La parallaxe de Gaia Data Release 1 fournit également une distance de 1,4 kpc, bien qu'il y ait une importante marge d'erreur[22]. Ella si fece promettere in cambio che l'avrebbe sposata e condotta con sé poiché dopo averlo aiutato il padre non l'avrebbe più accettata con sé. [19] The components are main sequence stars of spectral types B9V and A3V. R Coronae Borealis est une étoile supergéante jaune de faible masse particulière de la constellation de la Couronne boréale. In classical mythology Corona Borealis generally represented the crown given by the god Dionysus to the Cretan princess Ariadne and set by him in the heavens. [16] The brighter component is a rapidly oscillating Ap star, pulsating with a period of 16.2 minutes. In Welsh mythology, it was called Caer Arianrhod, "the Castle of the Silver Circle", and was the heavenly abode of the Lady Arianrhod. Other cultures likened the pattern to a circle of elders, an eagle's nest, a bear's den, or even a smokehole. [45] Epsilon itself is a 1.7 M☉ orange giant of spectral type K2III that has swollen to 21 R☉ and 151 L☉. [61] At the cluster's center is a large elliptical galaxy containing one of the most massive and most powerful supermassive black holes yet discovered. [31] Normally placid around magnitude 10—it has a minimum of 10.2 and maximum of 9.9—it brightens to magnitude 2 in a period of hours, caused by a nuclear chain reaction and the subsequent explosion. [34], There are several other variables of reasonable brightness for amateur astronomer to observe, including three Mira-type long period variables:[30] S Coronae Borealis ranges between magnitudes 5.8 and 14.1 over a period of 360 days. [49] XO-1 is a magnitude 11 yellow main-sequence star located approximately 560 light-years away,[50] of spectral type G1V with a mass and radius similar to the Sun. Corona Borealis is associated with the myth of Princess Ariadne of Crete, most famous for her part in helping the Greek hero Theseus defeat the Minotaur, the creature with a human body and head of a bull that lived in a labyrinth designed by Daedalus. The vessel CORONA BOREALE (IMO: 9509358, MMSI 247257300) is a Pusher Tug built in 2009 (11 years old) and currently sailing under the flag of Italy. It is about 1.2 billion light-years away. II. [11] It is actually a complex system composed of two stars around as massive as the Sun that orbit each other every 1.14 days, orbited by a third Sun-like star every 726 years. À des intervalles irréguliers allant de quelques années à des décennies, R Coronae Borealis perd sa luminosité normale voisine de la 6ème magnitude sur une période allant de quelques mois à parfois quelques années. R Coronae Borealis est une étoile faiblement visible à l'oeil nu, mais elle ne possède aucun nom traditionnel. He named them 20 and 21 Coronae Borealis in his catalogue, alongside the designations Nu1 and Nu2 respectively. R Coronae Borealis possède environ 90 % d'hélium et moins de 1 % hydrogène. Direct imaging with the Hubble Space Telescope shows extensive dust clouds out to a radius of around 2000 AU from the star, corresponding with a stream of fine dust (composed of grains 5 nm in diameter) associated with the star's stellar wind and coarser dust (composed of grains with a diameter of around 0.14 µm) ejected periodically. L'affaiblissement est moins prononcé aux longueurs d'onde plus élevées. Lors des mois suivants, elle revient graduellement à sa luminosité normale, lui donnant le surnom "nova réversible". Discovered by the Doppler method in 2010, it takes 176 days to complete an orbit. La plupart du temps, elle montre des variations de l'ordre d'un dixième de magnitude sur des périodes mal définies de 40 et de 51 jours. Nella parte sudoccidentale della costellazione è presente un celebre Ammasso di galassie, noto come Abell 2065, che conta decine di galassie. It has a surface temperature of 5180 K.[22] For most of its existence, Delta Coronae Borealis was a blue-white main-sequence star of spectral type B before it ran out of hydrogen fuel in its core. [24] Nu Coronae Borealis is an optical double, whose components are a similar distance from Earth but have different radial velocities, hence are assumed to be unrelated. Star C is a yellow white star of spectral type F3V around 1.41 times as massive as the Sun, which has just started brightening and moving off the main sequence. [8], In Welsh mythology, it was called Caer Arianrhod, "the Castle of the Silver Circle", and was the heavenly abode of the Lady Arianrhod. Les modèles des étoiles post-AGB prévoient qu'une étoile ayant l'apparence de R CrB devrait avoir une masse autour de 0.6 M☉, et on pense donc qu'elle pourrait avoir été formée par la fusion d'une naine blanche carbone-oxygène et d'une naine blanche à hélium[23]. [69] The constellation also symbolised the smokehole over a fireplace, which conveyed their messages to the gods, as well as how chiefs should come together to consider matters of importance. [31] On a larger scale still, Abell 2065, along with Abell 2061, Abell 2067, Abell 2079, Abell 2089, and Abell 2092, make up the Corona Borealis Supercluster. In 2006 the hot Jupiter exoplanet XO-1b was discovered orbiting XO-1 by the transit method using the XO Telescope. Les modèles d'évolution des étoiles post-AGB donnent une masse de 0.66 M☉ pour R CrB, mais avec une marge considérable d'erreur[24]. Corona Borealis was one of the 48 constellations mentioned in the Almagest of classical astronomer Ptolemy. It was generally considered to represent a crown given by Dionysus to Ariadne, the daughter of Minos of Crete, after she had been abandoned by the Athenian prince Theseus. An outburst of T Coronae Borealis was first recorded in 1866; its second recorded outburst was in February 1946. Il n'y a pas de minimum fixe, mais l'étoile peut devenir plus faible que la 15ème magnitude dans le domaine visible[18]. Ce fut un minimum inhabituellement profond et exceptionnellement long, plus long même que le minimum profond de cinq ans de 1962-7. Signification: La Couronne boréale Mieux vue en: Juillet Famille: Grande Ourse Latitude: +90° à -50° Corona Borealis ou La Couronne boréale est l'une des 88 constellations qui divisent le ciel selon les travaux des astronomes modernes. [30] Located 1.5° northeast of Tau Coronae Borealis, W Coronae Borealis ranges between magnitudes 7.8 and 14.3 over a period of 238 days. [76] The constellation was featured as a main plot ingredient in the short story "Hypnos" by H. P. Lovecraft, published in 1923; it is the object of fear of one of the protagonists in the short story. ADS 9731 and Sigma Coronae Borealis are multiple star systems with six and five components respectively. [11] The primary is a white main-sequence star of spectral type A0V that is 2.91 times the mass of the Sun (M☉) and 57 times as luminous (L☉), and is surrounded by a debris disk out to a radius of around 60 astronomical units (AU). Le spectre d'absorption normal est remplacé par des raies en émission, en particulier HeI, CaII, NaI, et d'autres métaux. [6] It has a counterpart—Corona Australis—in the Southern Celestial Hemisphere. La cause de ce comportement est attribuée à une accumulation régulière de poussière de carbone dans l'atmosphère de l'étoile. Au maximum, le spectre indique que l'hydrogène dans R Coronae Borealis est fortement réduit, l'hélium est l'élément dominant et le carbone est fortement enrichi. [14] The brighter component, Theta Coronae Borealis A, is a blue-white star that spins extremely rapidly—at a rate of around 393 km per second. Le spectre est variable, plus particulièrement lors des périodes de faible luminosité. This pair is in a 450-year orbit with star B, a star of spectral type G4V that has around the same mass as the Sun. The smaller star is of spectral type F2V with a surface temperature of around 6750 K, and has around 1.4 M☉, 1.56 R☉, and between 4 and 5 L☉. Covering 179 square degrees and hence 0.433% of the sky, Corona Borealis ranks 73rd of the 88 modern constellations by area. La température au maximum est raisonnablement bien connue à 6900 K et décroît lors des affaiblissements lorsque la photosphère est obscurcie par la poussière qui condense. [33] These declines in magnitude come about as dust that has been ejected from the star obscures it. Its name in Tonga was uncertain; it was either called Ao-o-Uvea or Kau-kupenga. T Coronae Borealis is a binary star with a red-hued giant primary and a white dwarf secondary, the two stars orbiting each other over a period of approximately 8 months. [18], Flanking Alpha to the east is Gamma Coronae Borealis, yet another binary star system, whose components orbit each other every 92.94 years and are roughly as far apart from each other as the Sun and Neptune. Normally of magnitude 6, its brightness periodically drops as low as magnitude 15 and then slowly increases over the next several months. [57], Corona Borealis contains few galaxies observable with amateur telescopes. En août 2007, R Coronae Borealis commença à s'affaiblir jusqu'à un minimum sans précédent. The spectrum of Epsilon Coronae Borealis was analysed for seven years from 2005 to 2012, revealing a planet around 6.7 times as massive as Jupiter (MJ) orbiting every 418 days at an average distance of around 1.3 AU. Lors de sa découverte, elle fut décrite simplement comme "la variable de la Couronne boréale"[12]. XO-1 possiede un pianeta transiente. The beat period of 5.5 days indicates the time the accretion disk—which is asymmetrical—takes to precess around the star. [74] The Wardaman people of northern Australia held the constellation to be a gathering point for Men's Law, Women's Law and Law of both sexes come together and consider matters of existence. [66] This was also interpreted as a broken dish. Per consentire all'eroe di ritrovare l'uscita una volta imprigionato nel labirinto, Arianna gli dette un gomitolo di filo da sciogliere e dopo seguire a ritroso. [65], The Arabs called the constellation Alphecca (a name later given to Alpha Coronae Borealis), which means "separated" or "broken up" (الفكة al-Fakkah), a reference to the resemblance of the stars of Corona Borealis to a loose string of jewels. [70] The Shawnee people saw the stars as the Heavenly Sisters, who descended from the sky every night to dance on earth. [40] It is unusual in that it is a red star with a high proper motion (greater than 50 milliarcseconds a year). [56] No planet has been found, but a brown dwarf companion about 63 times as massive as Jupiter with a spectral type of L8 was discovered at a distance of 3640 AU from the pair in 2001. La costellazione della Corona Boreale si individua con facilità, grazie ad un asterismo a forma di "Y" il cui vertice è rappresentato dalla brillante stella Arturo, la quarta stella più brillante del cielo ad occhio nudo; vista dall'emisfero nord, la stanghetta di "sinistra" della Y è rappresentata dalla stella Alphekka, una stella bianca di sequenza principale di magnitudine 2,2, dunque perfettamente osservabile anche dai centri urbani. [58] NGC 6085 and 6086 are a faint spiral and elliptical galaxy respectively close enough to each other to be seen in the same visual field through a telescope. [38] Another red giant, RR Coronae Borealis is a M3-type semiregular variable star that varies between magnitudes 7.3 and 8.2 over 60.8 days. Typiquement l'étoile commence à revenir à sa brillance maximale presque immédiatement après son minimum, bien qu'occasionnellement ce retour puisse être interrompu par un autre affaiblissement. T Coronae Borealis, also known as the Blaze Star, is another unusual type of variable star known as a recurrent nova. Fin 2014, R Coronae Borealis brilla rapidement jusqu'à la 7ème magnitude mais commença ensuite à s'affaiblir de nouveau[19]. [47] HD 145457 is an orange giant of spectral type K0III found to have one planet of 2.9 MJ. In fact, it is an Algol-type eclipsing binary that varies by 0.1 magnitude with a period of 17.4 days. Elle est le prototype du type rare d'étoiles variables R CrB, dont la luminosité chute de plusieurs magnitudes à intervalles irréguliers. When she wore the crown at her marriage to Dionysus, he placed it in the heavens to commemorate their wedding. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", "Dynamical Masses of a Selected Sample of Orbital Binaries", "The X-ray activity of the slowly rotating G giant δ CrB", "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", "RX J1532.9+3021: Extreme Power of Black Hole Revealed", "Contradictions as a Source of Historical Perspective: Camp Circles and Sacred Poles", Warburg Institute Iconographic Database (over 140 medieval and early modern images of Corona Borealis), https://en.wikipedia.org/w/index.php?title=Corona_Borealis&oldid=987913816, Creative Commons Attribution-ShareAlike License, This page was last edited on 10 November 2020, at 00:01. Its Latin name, inspired by its shape, means "northern crown". Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It varies in brightness in an unusually complex manner: the two stars orbit each other every 111 minutes, yet there is another cycle of 112.6 minutes, which corresponds to the orbit of the disk around the degenerate star. Le reste est majoritairement du carbone[20]. Corona Borealis was one of the 48 constellations mentioned in the Almagest of classical astronomer Ptolemy. John Flamsteed did likewise with Nu Coronae Borealis; classed by Bayer as a single star, it was noted to be two close stars by Flamsteed. [47] This planet's mass is estimated at 2.5 MJ. Elle est le prototype du type rare d' étoiles variables R CrB, dont la luminosité chute de plusieurs magnitudes à intervalles irréguliers. La désignation d'étoile variable R Coronae Borealis fut introduite, comme "Coronae R", par Friedrich Wilhelm Argelander en 1950[15]. Cela la définit comme une étoile à hélium extrême enrichie en carbone. Dall'emisfero sud si mostra invece piuttosto bassa sull'orizzonte settentrionale ed appare visibile solo nelle notti autunnali e di inizio inverno australe. Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern. L'obscurcissement semble survenir plus près de l'étoile car les nuages de carbone condensent au niveau des régions de choc dans un front en expansion. La Corona Boreale è una figura tipica del cielo di primavera ed estate: dall'emisfero nord diventa ben visibile ad est nel cielo serale di fine febbraio, si mostra alta nel cielo nei mesi di maggio e giugno e nel corso dell'estate tende a declinare verso occidente, finché, alla fine di ottobre, non è più osservabile. L'imagerie directe avec le télescope spatial Hubble montre des nuages étendus de poussière jusqu'à un rayon d'environ 2000 unités astronomiques de R Coronae Borealis, correspondant à un courant de fine poussière (composée de grains de 5 nm de diamètre) associé au vent stellaire de l'étoile et de poussière plus grossière (composée de grains de diamètre environ 0,14 µm) éjectés périodiquement[25]. T Coronae Borealis is one of a handful of stars called recurrent novae, which include T Pyxidis and U Scorpii. [71], Polynesian peoples often recognized Corona Borealis; the people of the Tuamotus named it Na Kaua-ki-tokerau and probably Te Hetu. Five star systems have been found to have Jupiter-sized exoplanets. Les raies interdites "nébulaires" de [OI], [OII], et [NII] peuvent être parfois détectées[19]. Les raies de l'hélium et de métaux comme le calcium sont aussi présentes comme attendu[16]. La Corona Boreale è una figura tipica del cielo di primavera ed estate: dall'emisfero nord diventa ben visibile ad est nel cielo serale di fine febbraio, si mostra alta nel cielo nei mesi di maggio e giugno e nel corso dell'estate tende a declinare verso occidente, finché, alla fine di ottobre, non è più osservabile. "Corona Borealis, constellation boundary", "Corona Borealis, Constellation Boundary", "Tomography of a Stellar X-ray Corona: Alpha Coronae Borealis", "Stellar Kinematic Groups. [36] Varying between magnitudes 6.9 and 12.6 over a period of 357 days,[37] it is located near the junction of the border of Corona Borealis with Hercules and Bootes. [8] Chinese astronomers deemed nine stars to make up the asterism, adding Pi and Rho Coronae Borealis. [17] Near Nusakan is Theta Coronae Borealis, a binary system that shines with a combined magnitude of 4.13 located 380±20 light-years distant. The fourth and fifth components are a binary red dwarf system that is 14,000 AU distant from the other three stars. They married though she later returned to the sky, with her heartbroken husband and son following later. [31] An alternate version has the besotted Dionysus give the crown to Ariadne, who in turn gives it to Theseus after he arrives in Crete to kill the minotaur that the Cretans have demanded tribute from Athens to feed. Il existe deux modèles principaux pour expliquer la formation des étoiles R CrB : la fusion de deux naines blanches ; ou un flash de l'hélium très tardif dans une étoile post-AGB. [12] The secondary companion is a yellow main-sequence star of spectral type G5V that is a little smaller (0.9 times) the diameter of the Sun. [67] Among the Bedouins, the constellation was known as qaṣʿat al-masākīn (قصعة المساكين), or "the dish/bowl of the poor people". Finally the system of stars C and Dab, and the system of stars Aab and B, take more than 20,000 years to orbit each other. [78], Constellation in the northern celestial hemisphere, "Northern Crown" redirects here. Au minimum, le spectre montre le développement de nuages de carbone qui obscurcissent la photosphère, laissant parfois les raies chromosphériques visibles. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "CrB". Cet amas est souvent appelé l'amas de la Couronne Boréale. The Latin author Hyginus linked it to a crown or wreath worn by Bacchus (Dionysus) to disguise his appearance when first approaching Mount Olympus and revealing himself to the gods, having been previously hidden as yet another child of Jupiter's trysts with a mortal, in this case Semele. [77] Finnish band Cadacross released an album titled Corona Borealis in 2002. The primary is of magnitude 5.1 and the secondary is of magnitude 6.0. [28] ADS 9731 is an even rarer multiple system in the constellation, composed of six stars, two of which are spectroscopic binaries. [68], The Skidi people of Native Americans saw the stars of Corona Borealis representing a council of stars whose chief was Polaris. [43] Discovered in 1990, UW Coronae Borealis is a low-mass X-ray binary system composed of a star less massive than the Sun and a neutron star surrounded by an accretion disk that draws material from the companion star. [59] Abell 2142 is a huge (six million light-year diameter), X-ray luminous galaxy cluster that is the result of an ongoing merger between two galaxy clusters. [5] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of eight segments (illustrated in infobox). Flamsteed numérota toutes les étoiles de Bayer mais ne rajouta aucune designation supplémentaire pour les étoiles plus faibles, et donc R Coronae Borealis n'apparaît dans aucun de ces deux catalogues[12]. Il y a également une coquille de 2 M☉ large d'environ 4 pc contenant de la poussière à 25 K, qui pourrait être une nébuleuse planétaire fossile[21]. In the myth, Ariadne married the god Dionysus. R Coronae Borealis elle-même brille normalement avec une magnitude d'environ 6, tout juste visible à l'œil nu, mais à des intervalles allant de quelques mois à plusieurs années, elle s'affaiblit jusqu'à atteindre parfois la 15ème magnitude. Les raies de l'hydrogène sont faibles ou absentes, tandis que les raies du carbone et les bandes moléculaires du cyanogène (CN) et de C2 sont exceptionnellement fortes. Elle fut ensuite appelée Variabilis Coronae, "(Etoile) Variable de Coronae (Borealis)"[13]. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 15h 16.0m and 16h 25.1m , while the declination coordinates are between 39.71° and 25.54°. [32] R Coronae Borealis is a yellow-hued variable supergiant star, over 7000 light-years from Earth, and prototype of a class of stars known as R Coronae Borealis variables. Track on Map Add Photo Add to Fleet Port Calls Cependant, R Coronae Borealis s'affaiblit de nouveau presque jusqu'à la 15ème magnitude et en août 2014 elle était en dessous de la 10ème magnitude depuis 7 ans. Fra le stelle variabilili della costellazione ve ne sono alcune di facile osservazione. [b][4], Alpha Coronae Borealis (officially named Alphecca by the IAU, but sometimes also known as Gemma) appears as a blue-white star of magnitude 2.2. La distance de R Coronae Borealis n'est pas connue exactement, mais est estimée à 1,4 kiloparsecs à partir d'hypothèses faites sur sa luminosité intrinsèque. [4][a] It is bordered by Boötes to the north and west, Serpens Caput to the south, and Hercules to the east. Alphecca signifies the youngest and most comely sister, who was seized by a hunter who transformed into a field mouse to get close to her. [14][27] Sigma Coronae Borealis, on the other hand, is a true multiple star system divisible by small amateur telescopes. Localisation dans la constellation : Couronne boréale, R Coronae Borealis, R CrB, GSC2 N1330022410, 2MASS J15483440+2809242, AG+28° 1513, GSC 02039-01605, BD+28 2477, HD 141527, PLX 3581, TYC 2039-1605-1, CDS 886, PPM 104338, GC 21257, HIP 77442, RAFGL 4219, GCRV 9116, HR 5880, AAVSO 1544+28A, IRAS 15465 +2818, SAO 84015. Sky Catalogue 2000.0: Volume 2: Double Stars, Variable Stars and NonstellarObjects, The International Variable Stars Index - AAVSO, The Cambridge Guide to the Constellations, A Walk through the Heavens: A Guide to Stars and Constellations and their Legends, Astronomia - Dalla Terra ai confini dell'Universo, Stelle principali della costellazione della Corona Boreale, Oggetti non stellari nella costellazione della Corona Boreale, https://it.wikipedia.org/w/index.php?title=Corona_Boreale&oldid=112325060, Voci non biografiche con codici di controllo di autorità, licenza Creative Commons Attribuzione-Condividi allo stesso modo. The brightest star is the magnitude 2.2 Alpha Coronae Borealis. [23], Zeta Coronae Borealis is a double star with two blue-white components 6.3 arcseconds apart that can be readily separated at 100x magnification. For the d20 System game, see, The 41 additional constellations added in the 16th, 17th and 18th centuries, While parts of the constellation technically rise above the horizon to observers between the 50°S and. La costellazione non contiene alcuno oggetto del profondo cielo degno di nota: le galassie in questa regione di cielo sono tutte molto lontane e deboli. A Be star, it is surrounded by a debris disk. Sa couleur et sa magnitude apparente ne sont pas compatibles avec le fait d'être à la même distance que R Coronae Borealis[19]. The yellow supergiant R Coronae Borealis is the prototype of a rare class of giant stars—the R Coronae Borealis variables—that are extremely hydrogen deficient, and thought to result from the merger of two white dwarfs.
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