Alpha Ursae Majoris, Latinised from α Ursae Majoris, formally named Dubhe/ˈdʌbiː/,[12][13] is, despite being designated "α" (alpha), the second-brightest object in the northern constellation of Ursa Major. This prominent asterism is known as the Big Dipper, the Plough, and the Great Bear. Alpha Ursae Majoris is the northern of the 'pointers' (or 'guards'), the second being Beta Ursae Majoris, or 'Merak' – this pair of stars point towards Polaris, the North Star.[14]
α Ursae Majoris is located at a distance of approximately 123 light years from the Sun, based on parallax measurements. It is a spectroscopic binary made up of the stars designated α Ursae Majoris A and α Ursae Majoris B. The pair orbit at a separation of about 23[4]astronomical units (AU) with a period of 44.5 years and an eccentricity (ovalness) of 0.44.[8] There is another spectroscopic binary at an angular separation of 7.1 arcminutes, forming a 7th magnitude pair showing an F8 spectral type with an orbital period of 6.035 days and an eccentricity of 0.09. It is sometimes referred to as Alpha Ursae Majoris C, but is separately catalogued as HD 95638.[4] Together they form a quadruple star system.[15]
Component A is the system's primary, and it is a giant star that has evolved away from the main sequence after consuming the hydrogen at its core. It is 280 million years old with 3.4 times the mass and has expanded 17 times the radius of the Sun. The star is radiating 165 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,012 K.[9] The secondary star, component B, is a main sequence star that has a stellar classification of F0V. α Ursae Majoris has been reported to vary in brightness by about a thousandth of a magnitude. Ten radial oscillation modes have been detected, with periods between 6.4 hours and 6.4 days.[16]
Although it is part of the constellation of Ursa Major, it is not part of the Ursa Major Moving Group of stars that have a common motion through space.[17]
NomenclatureEdit
α Ursae Majoris (Latinised to Alpha Ursae Majoris) is the star system's Bayer designation.
It bore the traditional name Dubhe, which is derived from the Arabic for 'bear', dubb, from the phrase ظهر الدب الاكبرżahr ad-dubb al-akbar 'the back of the Greater Bear'. The ancient Egyptians called it Ak, meaning 'The Eye'.[18] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[19] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[20] included a table of the first two batches of names approved by the WGSN; which included Dubhe for the star α Ursae Majoris A.
In Chinese, 北斗 Běi Dǒu, meaning Northern Dipper, refers to an asterism equivalent to the Big Dipper. Consequently, the Chinese name for Alpha Ursae Majoris itself is 北斗一 Běi Dǒu yī, (English: the First Star of Northern Dipper) and 天樞 Tiān Shū, (English: Star of Celestial Pivot).[21]
^ abcdevan Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
^ abcJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J
^ abGuenther, D. B.; et al. (2000). "Evolutionary Model and Oscillation Frequencies for α Ursae Majoris: A Comparison with Observations". The Astrophysical Journal. 530 (1): L45–L48. Bibcode:2000ApJ...530L..45G. doi:10.1086/312473. PMID 10642202.
^ abcTokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
^Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
^Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
^ abCarney, Bruce W.; et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal, 135 (3): 892–906, arXiv:0711.4984, Bibcode:2008AJ....135..892C, doi:10.1088/0004-6256/135/3/892, S2CID 2756572
^ abGray, David F. (December 2018). "Spectroscopy of the K0 Binary Giant α UMa". The Astrophysical Journal. 869 (1): 14. Bibcode:2018ApJ...869...81G. doi:10.3847/1538-4357/aae9e6. S2CID 125789271. 81.
^ abBaines, E.; et al. (2017). "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer". The Astronomical Journal. 155 (1): 30. arXiv:1712.08109. Bibcode:2018AJ....155...30B. doi:10.3847/1538-3881/aa9d8b. S2CID 119427037.
^McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527
^Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN978-1-931559-44-7.
^"IAU Catalog of Star Names". Retrieved 28 July 2016.
^Streicher, Magda (April 2009). "Plough northwards, to the Big Dipper". Monthly Notes of the Astronomical Society of South Africa. 68 (3 and 4): 78–83. Bibcode:2009MNSSA..68...78S.
^Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
^Buzasi, D.; Catanzarite, J.; Laher, R.; Conrow, T.; Shupe, D.; Gautier, T. N.; Kreidl, T.; Everett, D. (2000). "The Detection of Multimodal Oscillations on α Ursae Majoris". The Astrophysical Journal. 532 (2): L133–L136. arXiv:astro-ph/0002512. Bibcode:2000ApJ...532L.133B. doi:10.1086/312573. PMID 10715242. S2CID 119057234.
^Motz, Lloyd; Nathanson, Carol (1988). The Constellations: An Enthusiast's Guide To The Night Sky. Doubleday. p. 39. ISBN978-0385176002.
^ abAllen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 438. ISBN0-486-21079-0. Retrieved 2012-09-04.
^"IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
^"Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
^(in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 15 日
^. onlinelibrary.utah.gov. Archived from the original on 2019-02-08. Retrieved 2019-11-25.
alpha, ursae, majoris, latinised, from, ursae, majoris, formally, named, dubhe, despite, being, designated, alpha, second, brightest, object, northern, constellation, ursa, major, this, prominent, asterism, known, dipper, plough, great, bear, northern, pointer. Alpha Ursae Majoris Latinised from a Ursae Majoris formally named Dubhe ˈ d ʌ b iː 12 13 is despite being designated a alpha the second brightest object in the northern constellation of Ursa Major This prominent asterism is known as the Big Dipper the Plough and the Great Bear Alpha Ursae Majoris is the northern of the pointers or guards the second being Beta Ursae Majoris or Merak this pair of stars point towards Polaris the North Star 14 a Ursae MajorisLocation of a Ursae Majoris circled Observation dataEpoch J2000 Equinox J2000Constellation Ursa MajorRight ascension 11h 03m 43 67152s 1 Declination 61 45 03 7249 1 Apparent magnitude V 1 79 2 CharacteristicsSpectral type K0III 3 F0V 4 U B color index 0 93 2 B V color index 1 07 2 Variable type Suspected 5 AstrometryRadial velocity Rv 9 4 0 3 6 km sProper motion m RA 134 11 1 mas yr Dec 34 70 1 mas yrParallax p 26 54 0 48 mas 1 Distance123 2 ly 37 7 0 7 pc Absolute magnitude MV 1 10 0 04 7 Orbit 8 Companiona UMa BPeriod P 44 45 0 11 yrSemi major axis a 0 590 0 026 Eccentricity e 0 439 0 004Inclination i 159 9 3 5 Longitude of the node W 9 3 8 2 Periastron epoch T 2 002 17 0 09Argument of periastron w secondary 232 8 7 9 Details 9 a UMa AMass3 44 0 11 M Radius17 03 0 13 R Luminosity165 1 8 3 L Surface gravity log g 2 20 cgsTemperature5 012 65 KMetallicity Fe H 0 20 0 07 10 dexRotational velocity v sin i 2 6 1 0 7 km sAge280 30 Myra UMa BMass 1 6 3 M Other designationsDubhe Ak a Ursae Majoris a UMa Alpha UMa 50 UMa NSV 5070 BD 62 1161 FK5 417 GC 15185 HD 95689 HIP 54061 HR 4301 SAO 15384 PPM 17705 ADS 8035 CCDM J11037 6145AB WDS J11037 6145AB 11 Database referencesSIMBADdata Contents 1 Stellar system 2 Nomenclature 3 In culture 4 See also 5 ReferencesStellar system Edit nbsp a Ursae Majoris A and faint companion binariesa Ursae Majoris is located at a distance of approximately 123 light years from the Sun based on parallax measurements It is a spectroscopic binary made up of the stars designated a Ursae Majoris A and a Ursae Majoris B The pair orbit at a separation of about 23 4 astronomical units AU with a period of 44 5 years and an eccentricity ovalness of 0 44 8 There is another spectroscopic binary at an angular separation of 7 1 arcminutes forming a 7th magnitude pair showing an F8 spectral type with an orbital period of 6 035 days and an eccentricity of 0 09 It is sometimes referred to as Alpha Ursae Majoris C but is separately catalogued as HD 95638 4 Together they form a quadruple star system 15 Component A is the system s primary and it is a giant star that has evolved away from the main sequence after consuming the hydrogen at its core It is 280 million years old with 3 4 times the mass and has expanded 17 times the radius of the Sun The star is radiating 165 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5 012 K 9 The secondary star component B is a main sequence star that has a stellar classification of F0V a Ursae Majoris has been reported to vary in brightness by about a thousandth of a magnitude Ten radial oscillation modes have been detected with periods between 6 4 hours and 6 4 days 16 Although it is part of the constellation of Ursa Major it is not part of the Ursa Major Moving Group of stars that have a common motion through space 17 Nomenclature Edita Ursae Majoris Latinised to Alpha Ursae Majoris is the star system s Bayer designation It bore the traditional name Dubhe which is derived from the Arabic for bear dubb from the phrase ظهر الدب الاكبر zahr ad dubb al akbar the back of the Greater Bear The ancient Egyptians called it Ak meaning The Eye 18 In 2016 the International Astronomical Union organized a Working Group on Star Names WGSN 19 to catalog and standardize proper names for stars The WGSN s first bulletin of July 2016 20 included a table of the first two batches of names approved by the WGSN which included Dubhe for the star a Ursae Majoris A The Hindus refer to the star as Kratu one of the Seven Rishis 18 In Chinese 北斗 Bei Dǒu meaning Northern Dipper refers to an asterism equivalent to the Big Dipper Consequently the Chinese name for Alpha Ursae Majoris itself is 北斗一 Bei Dǒu yi English the First Star of Northern Dipper and 天樞 Tian Shu English Star of Celestial Pivot 21 In culture EditDubhe is the official star of the State of Utah 22 Dubhe was a ship in the United States Navy The Danish National Home Guard Navy ship MHV806 is also namedDubhe See also EditLists of stars by constellationReferences Edit a b c d e van Leeuwen F November 2007 Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 a b c Johnson H L et al 1966 UBVRIJKL photometry of the bright stars Communications of the Lunar and Planetary Laboratory 4 99 99 Bibcode 1966CoLPL 4 99J a b Guenther D B et al 2000 Evolutionary Model and Oscillation Frequencies for a Ursae Majoris A Comparison with Observations The Astrophysical Journal 530 1 L45 L48 Bibcode 2000ApJ 530L 45G doi 10 1086 312473 PMID 10642202 a b c Tokovinin A A 1997 MSC a catalogue of physical multiple stars Astronomy and Astrophysics Supplement Series 124 75 84 Bibcode 1997A amp AS 124 75T doi 10 1051 aas 1997181 Samus N N Durlevich O V et al 2009 VizieR Online Data Catalog General Catalogue of Variable Stars Samus 2007 2013 VizieR On line Data Catalog B GCVS Originally Published in 2009yCat 102025S 1 Bibcode 2009yCat 102025S Gontcharov G A November 2006 Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system Astronomy Letters 32 11 759 771 arXiv 1606 08053 Bibcode 2006AstL 32 759G doi 10 1134 S1063773706110065 S2CID 119231169 a b Carney Bruce W et al March 2008 Rotation and Macroturbulence in Metal Poor Field Red Giant and Red Horizontal Branch Stars The Astronomical Journal 135 3 892 906 arXiv 0711 4984 Bibcode 2008AJ 135 892C doi 10 1088 0004 6256 135 3 892 S2CID 2756572 a b Gray David F December 2018 Spectroscopy of the K0 Binary Giant a UMa The Astrophysical Journal 869 1 14 Bibcode 2018ApJ 869 81G doi 10 3847 1538 4357 aae9e6 S2CID 125789271 81 a b Baines E et al 2017 Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer The Astronomical Journal 155 1 30 arXiv 1712 08109 Bibcode 2018AJ 155 30B doi 10 3847 1538 3881 aa9d8b S2CID 119427037 McWilliam Andrew December 1990 High resolution spectroscopic survey of 671 GK giants I Stellar atmosphere parameters and abundances Astrophysical Journal Supplement Series 74 1075 1128 Bibcode 1990ApJS 74 1075M doi 10 1086 191527 DUBHE Spectroscopic binary SIMBAD Centre de Donnees astronomiques de Strasbourg retrieved 2011 12 23 Kunitzsch Paul Smart Tim 2006 A Dictionary of Modern star Names A Short Guide to 254 Star Names and Their Derivations 2nd rev ed Cambridge Massachusetts Sky Pub ISBN 978 1 931559 44 7 IAU Catalog of Star Names Retrieved 28 July 2016 Streicher Magda April 2009 Plough northwards to the Big Dipper Monthly Notes of the Astronomical Society of South Africa 68 3 and 4 78 83 Bibcode 2009MNSSA 68 78S Eggleton P P Tokovinin A A September 2008 A catalogue of multiplicity among bright stellar systems Monthly Notices of the Royal Astronomical Society 389 2 869 879 arXiv 0806 2878 Bibcode 2008MNRAS 389 869E doi 10 1111 j 1365 2966 2008 13596 x S2CID 14878976 Buzasi D Catanzarite J Laher R Conrow T Shupe D Gautier T N Kreidl T Everett D 2000 The Detection of Multimodal Oscillations on a Ursae Majoris The Astrophysical Journal 532 2 L133 L136 arXiv astro ph 0002512 Bibcode 2000ApJ 532L 133B doi 10 1086 312573 PMID 10715242 S2CID 119057234 Motz Lloyd Nathanson Carol 1988 The Constellations An Enthusiast s Guide To The Night Sky Doubleday p 39 ISBN 978 0385176002 a b Allen R H 1963 Star Names Their Lore and Meaning Reprint ed New York Dover Publications Inc p 438 ISBN 0 486 21079 0 Retrieved 2012 09 04 IAU Working Group on Star Names WGSN Retrieved 22 May 2016 Bulletin of the IAU Working Group on Star Names No 1 PDF Retrieved 28 July 2016 in Chinese AEEA Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 6 月 15 日 Pioneer Utah State Starl Dubhe onlinelibrary utah gov Archived from the original on 2019 02 08 Retrieved 2019 11 25 Portals nbsp Astronomy nbsp Stars nbsp Spaceflight nbsp Outer space nbsp Solar System Retrieved from https en wikipedia org w index php title Alpha Ursae Majoris amp oldid 1170125114, wikipedia, wiki, book, books, library,
