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- Alpha_Ophiuchi abstract "Alpha Ophiuchi (α Oph, α Ophiuchi) is the brightest star in the constellation Ophiuchus. It has the traditional name Ras Alhague, often condensed to Rasalhague.Alpha Ophiuchi is a binary star system with an orbital period of about 8.62 years. The orbital parameters were only poorly known until 2011 when observations using adaptive optics produced a better orbital fit, allowing the individual masses of the two components to be determined. The primary component, Alpha Ophiuchi A, has a mass of about 2.4 times the mass of the Sun, while the secondary, Alpha Ophiuchi B, has 0.85 solar masses. Estimates of the mass of the primary by other means range from a low of 1.92 to 2.10 solar masses, up to 2.84 or even 4.8 solar masses. The mass of the secondary suggests that it has a stellar classification in the range K5V to K7V, which indicates it is a main sequence star that is still generating energy by the thermonuclear fusion of hydrogen at its core. The pair reached periastron passage, or closest approach, around April 19, 2012, when they had an angular separation of 50 milliarcseconds.This star system has a combined apparent magnitude of +2.08 and is located at a distance of about 48.6 light-years (14.9 parsecs) from the Earth. The stellar classification of A5 III indicates that the primary is a giant star that has evolved away from the main sequence after consuming the hydrogen at its core. It is radiating about 25 times the luminosity of the Sun and has an effective temperature of about 8,000 K, giving it the characteristic white hue of an A-type star.Alpha Ophiuchi A is a rapidly rotating star with a projected rotational velocity of 240 km s−1. It is spinning at a rate of about 88.5% of the velocity that would cause the star to break up. The resulting equatorial bulge is about 20% larger than the polar radius, giving the star the shape of an oblate spheroid. Because of this distorted shape, the poles have an effective temperature about 1,840 K greater than along the equator. The axis of rotation of the star is inclined about 87.°7 ± 0°4 to the line of sight from the Earth, so that it is being observed from nearly equator-on.The spectrum of Alpha Ophiuchi shows an anomalously high level of absorption of the lines for singly-ionized calcium (Ca II). However, this is likely the result of interstellar matter between the Earth and the star, rather than a property of the star or circumstellar dust.".
- Alpha_Ophiuchi thumbnail Ophiuchus_IAU.svg?width=300.
- Alpha_Ophiuchi wikiPageExternalLink rasalhague.html.
- Alpha_Ophiuchi wikiPageID "1522419".
- Alpha_Ophiuchi wikiPageLength "12031".
- Alpha_Ophiuchi wikiPageOutDegree "40".
- Alpha_Ophiuchi wikiPageRevisionID "698848355".
- Alpha_Ophiuchi wikiPageWikiLink Adaptive_optics.
- Alpha_Ophiuchi wikiPageWikiLink Apparent_magnitude.
- Alpha_Ophiuchi wikiPageWikiLink Apsis.
- Alpha_Ophiuchi wikiPageWikiLink Arabic.
- Alpha_Ophiuchi wikiPageWikiLink Binary_star.
- Alpha_Ophiuchi wikiPageWikiLink Bright_Star_Catalogue.
- Alpha_Ophiuchi wikiPageWikiLink Catalogues_of_Fundamental_Stars.
- Alpha_Ophiuchi wikiPageWikiLink Category:A-type_giants.
- Alpha_Ophiuchi wikiPageWikiLink Category:Bayer_objects.
- Alpha_Ophiuchi wikiPageWikiLink Category:Ophiuchus_(constellation).
- Alpha_Ophiuchi wikiPageWikiLink Category:Stars_with_proper_names.
- Alpha_Ophiuchi wikiPageWikiLink Chinese_constellations.
- Alpha_Ophiuchi wikiPageWikiLink Chinese_language.
- Alpha_Ophiuchi wikiPageWikiLink Constellation.
- Alpha_Ophiuchi wikiPageWikiLink Durchmusterung.
- Alpha_Ophiuchi wikiPageWikiLink Earth.
- Alpha_Ophiuchi wikiPageWikiLink Effective_temperature.
- Alpha_Ophiuchi wikiPageWikiLink Giant_star.
- Alpha_Ophiuchi wikiPageWikiLink Heavenly_Market_enclosure.
- Alpha_Ophiuchi wikiPageWikiLink Henry_Draper_Catalogue.
- Alpha_Ophiuchi wikiPageWikiLink Hipparcos.
- Alpha_Ophiuchi wikiPageWikiLink Julian_day.
- Alpha_Ophiuchi wikiPageWikiLink Main_sequence.
- Alpha_Ophiuchi wikiPageWikiLink Mandarin_Chinese.
- Alpha_Ophiuchi wikiPageWikiLink Minute_and_second_of_arc.
- Alpha_Ophiuchi wikiPageWikiLink Ophiuchus.
- Alpha_Ophiuchi wikiPageWikiLink Smithsonian_Astrophysical_Observatory_Star_Catalog.
- Alpha_Ophiuchi wikiPageWikiLink Solar_luminosity.
- Alpha_Ophiuchi wikiPageWikiLink Solar_mass.
- Alpha_Ophiuchi wikiPageWikiLink Spectrum.
- Alpha_Ophiuchi wikiPageWikiLink Spheroid.
- Alpha_Ophiuchi wikiPageWikiLink Star.
- Alpha_Ophiuchi wikiPageWikiLink Stellar_classification.
- Alpha_Ophiuchi wikiPageWikiLink Stellar_rotation.
- Alpha_Ophiuchi wikiPageWikiLink Thermonuclear_fusion.
- Alpha_Ophiuchi wikiPageWikiLink File:Cercle_rouge_100%25.svg.
- Alpha_Ophiuchi wikiPageWikiLink File:Ophiuchus_IAU.svg.
- Alpha_Ophiuchi wikiPageWikiLinkText "Alpha Ophiuchi".
- Alpha_Ophiuchi wikiPageWikiLinkText "Astrologer".
- Alpha_Ophiuchi wikiPageWikiLinkText "Ras Alhague".
- Alpha_Ophiuchi wikiPageWikiLinkText "Rasalague".
- Alpha_Ophiuchi wikiPageWikiLinkText "Rasalhague".
- Alpha_Ophiuchi wikiPageWikiLinkText "α Oph".
- Alpha_Ophiuchi wikiPageWikiLinkText "α Ophiuchi".
- Alpha_Ophiuchi absmagV "+1.248".
- Alpha_Ophiuchi appmagV "2.07".
- Alpha_Ophiuchi axisUnitless "mas".
- Alpha_Ophiuchi bV "+0.15".
- Alpha_Ophiuchi class "A5 III / K5–7 V".
- Alpha_Ophiuchi component "α Oph A".
- Alpha_Ophiuchi component "α Oph B".
- Alpha_Ophiuchi constell Ophiuchus.
- Alpha_Ophiuchi epoch "J2000".
- Alpha_Ophiuchi gravity "3.91".
- Alpha_Ophiuchi luminosity "25.1".
- Alpha_Ophiuchi pError "1.06".
- Alpha_Ophiuchi parallax "67.13".
- Alpha_Ophiuchi periastron "JD".
- Alpha_Ophiuchi periodUnitless "days".
- Alpha_Ophiuchi propMoDec "-221.57".
- Alpha_Ophiuchi propMoRa "108.07".
- Alpha_Ophiuchi radialV "+12.6".
- Alpha_Ophiuchi radius "2.6".
- Alpha_Ophiuchi rotationalVelocity "240".
- Alpha_Ophiuchi temperature "–".
- Alpha_Ophiuchi uB "+0.10".
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Citation.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Convert.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:DEC.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:RA.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Reflist.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_astrometry.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_begin.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_catalog.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_character.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_detail.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_end.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_image.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_observe.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Starbox_orbit.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Stars_of_Ophiuchus.
- Alpha_Ophiuchi wikiPageUsesTemplate Template:Val.
- Alpha_Ophiuchi subject Category:A-type_giants.
- Alpha_Ophiuchi subject Category:Bayer_objects.
- Alpha_Ophiuchi subject Category:Ophiuchus_(constellation).
- Alpha_Ophiuchi subject Category:Stars_with_proper_names.
- Alpha_Ophiuchi hypernym Star.
- Alpha_Ophiuchi type CelestialBody.
- Alpha_Ophiuchi type Place.
- Alpha_Ophiuchi type Star.
- Alpha_Ophiuchi type Catalogue.
- Alpha_Ophiuchi type Location.
- Alpha_Ophiuchi type Place.