fbpx
Wikipedia

Alpha Herculis

December 04, 2023

Alpha Herculis (α Herculis, abbreviated Alpha Her, α Her), also designated 64 Herculis, is a multiple star system in the constellation of Hercules. Appearing as a single point of light to the naked eye, it is resolvable into a number of components through a telescope. It has a combined apparent magnitude of 3.08, although the brightest component is variable in brightness. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 360 light-years (110 parsecs) distant from the Sun.

α Herculis
Location of α Herculis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
A
Right ascension 17h 14m 38.853s[1]
Declination +14° 23′ 25.34″[1]
Apparent magnitude (V) 3.350[1] (2.7–4.0[2])
B
Right ascension 17h 14m 39.181s[1]
Declination +14° 23′ 23.98″[1]
Apparent magnitude (V) 5.322[1]
Characteristics
A
Evolutionary stage AGB[3]
Spectral type M5 Ib-II[3]
U−B color index +1.01[4]
B−V color index +1.45[4]
Variable type SRc[2]
B
Spectral type G8III + A9IV-V[3]
Astrometry
Proper motion (μ) RA: −7.32[5] mas/yr
Dec.: 36.07[5] mas/yr
Parallax (π)9.07 ± 1.32 mas[5]
Distanceapprox. 360 ly
(approx. 110 pc)
Absolute magnitude (MV)−2.3[6] + 1.8 + 2.8[7]
Details
A
Mass2.5+1.6
−1.1[8] M☉
Radius284 ± 60, 264–303[3] R☉
Luminosity7,244–9,333[3] L☉
Surface gravity (log g)−0.41±0.19[9] cgs
Temperature3,155–3,365[3] K
Ba
Mass~2.5[3] M☉
Luminosity126[3] L☉
Temperature4,900[3] K
Bb
Mass~2[3] M☉
Luminosity26[3] L☉
Temperature7,350[3] K
Age0.41–1.25[3] Gyr
Other designations
Ras Algethi, Rasalgethi, α Her, 64 Her, BD+14°3207, HIP 84345, CCDM J17146+1424, AAVSO 1710+14, WDS J17146+1423[10]
A: HD 156014, HR 6406, SAO 102680
B: HD 156015, HR 6407, SAO 102681
Database references
SIMBADα Her
A
B

System edit

 
A view of Alpha Herculis in a small telescope. The components A and B are resolved with angular separation of 4.64'' (in 2020).

Alpha Herculis is a triple star system. The primary (brightest) of the three stars, designated α1 Herculis or α Herculis A, is a pulsating variable star on the asymptotic giant branch (AGB), and is the second nearest AGB star after Mira. The primary star forms a visual binary pair with a second star, which is itself a spectroscopic binary.[3]

Alpha Herculis also forms the A and B components of a wider system designated WDS J17146+1423, with two additional faint visual companions designated WDS J17146+1423C and D.[11] The two fainter stars are far more distant than the triple system.[12]

Nomenclature edit

α Herculis (Latinised to Alpha Herculis) is the system's Bayer designation; α1 and α2 Herculis, those of its two visible components. 64 Herculis is the system's Flamsteed designation. WDS J17146+1423 is the wider system's designation in the Washington Double Star Catalog. The designations of Alpha Herculis' main components as Alpha Herculis A and B and the wider system's four components as WDS J17146+1423A, B, C and D, together with the spectroscopic pair - Alpha Herculis Ba and Bb - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[13]

Alpha Herculis bore the traditional name Rasalgethi or Ras Algethi (Arabic: رأس الجاثي ra‘is al-jāthī 'Head of the Kneeler').[14] 'Head' comes from the fact that in antiquity Hercules was depicted upside down on maps of the constellation. In 2016, the IAU organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN approved the name Rasalgethi for the component Alpha Herculis A (α1) on 30 June 2016 and it is now so included in the List of IAU-approved Star Names.[15]

The term ra's al-jaθiyy or Ras al Djathi appeared in the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, which was translated into Latin as Caput Ingeniculi.[16]

In Chinese astronomy, Alpha Herculis is called 帝座, Pinyin: Dìzuò, meaning 'Emperor's Seat'. The star is seen as marking itself, and stands alone in the center of the Emperor's Seat asterism, Heavenly Market enclosure (see: Chinese constellations).[17] 帝座 (Dìzuò) was westernized into Ti Tso by R.H. Allen, with the same meaning [18]

Properties edit

 
A light curve for Alpha Herculis A, plotted from data published by Wasatonic (1997)[19]

Alpha Herculis A and B are more than 500 AU apart, with an estimated orbital period of approximately 3600 years.[citation needed] A presents as a relatively massive red bright giant, but radial velocity measurements suggest a companion with a period of the order of a decade.[11] B's two components are a primary yellow giant star and a secondary, yellow-white dwarf star in a 51.578 day orbit.[20]

Alpha Herculis A is an asymptotic giant branch (AGB) star, a luminous red giant that has both hydrogen and helium shells around a degenerate carbon-oxygen core. It is the second nearest AGB star to the Sun.[3] The angular diameter of the star has been measured with an interferometer as 34 ± 0.8 mas, or 0.034 arcseconds.[21] At its estimated distance of 110 parsecs this corresponds to a radius of about 280 million kilometers (or 170 million miles), which is roughly 400 R☉ or 1.87 AU.[a] If Alpha Herculis were at the center of the Solar System its radius would extend past the orbit of Mars at 1.5 AU but not quite as far as the asteroid belt. The red giant is estimated to have started its life with about 2.175-3.250 M☉.[3]

Alpha Herculis A has been specified as a standard star for the spectral class M5 Ib-II.[3] Like most type M stars near the end of their lives, Alpha Herculis is experiencing a high degree of stellar mass loss creating a sparse, gaseous envelope that extends at least 930 AU.[20] It is a semiregular variable with complex changes in brightness with periods ranging from a few weeks to many years. The most noticeable variations occur at timescales of 80–140 days and at 1,000 - 3,000 days. The strongest detectable period is 128 days.[22] The full range in brightness is from magnitude 2.7 to 4.0,[2] but it usually varies over a much smaller range of around 0.6 magnitudes.[22]

Notes edit

  1. ^ To determine Rasalgethi's radius in terms of solar units, the calculations begin with the formula for angular diameter as follows:
     
    where δ equals Rasalgethi's angular diameter in arcseconds, dR the star's diameter in AU, and DR the Distance from Earth in parsecs. If one knows the angular diameter and the Distance, then one can solve for dR as follows:
     .
    To obtain Rasalgheti's radius:
     .
    Converting into Solar units, 1 AU = 149,597,871 km and the mean radius of the Sun = 696,000 km, hence the calculation:
      (rounded).

References edit

  1. ^ a b c d e f Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 0333750888.
  2. ^ a b c 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.
  3. ^ a b c d e f g h i j k l m n o p q Moravveji, Ehsan; Guinan, Edward F.; Khosroshahi, Habib; Wasatonic, Rick (2013). "The Age and Mass of the α Herculis Triple-star System from a MESA Grid of Rotating Stars with 1.3 <= M/M ⊙ <= 8.0". The Astronomical Journal. 146 (6): 148. arXiv:1308.1632. Bibcode:2013AJ....146..148M. doi:10.1088/0004-6256/146/6/148. S2CID 117872505.
  4. ^ a b Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  5. ^ a b c van Leeuwen, F (November 2007). "Hipparcos, the New Reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  6. ^ Huang, W.; Wallerstein, G.; Stone, M. (2012). "A catalogue of Paschen-line profiles in standard stars". Astronomy & Astrophysics. 547: A62. arXiv:1210.7893. Bibcode:2012A&A...547A..62H. doi:10.1051/0004-6361/201219804. S2CID 119286159.
  7. ^ Reimers, D. (1977). "On the absolute scale of mass-loss in red giants. I - Circumstellar absorption lines in the spectrum of the visual companion of Alpha-1 HER". Astronomy and Astrophysics. 61: 217. Bibcode:1977A&A....61..217R.
  8. ^ Moravveji, E.; Guinan, E. F.; Sobouti, Y. (2011). "On the Mass and Evolutionary Status of the Bright Red AGB Supergiant α1 Herculis". Why Galaxies Care About Agb Stars Ii: Shining Examples and Common Inhabitants. 445: 163. Bibcode:2011ASPC..445..163M.
  9. ^ Schröder, K.-P.; Cuntz, M. (April 2007), "A critical test of empirical mass loss formulas applied to individual giants and supergiants", Astronomy and Astrophysics, 465 (2): 593–601, arXiv:astro-ph/0702172, Bibcode:2007A&A...465..593S, doi:10.1051/0004-6361:20066633, S2CID 55901104
  10. ^ "alf Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-09-26.
  11. ^ a b . United States Naval Observatory. Archived from the original on 2011-02-14. Retrieved 2018-07-10.
  12. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
  13. ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  14. ^ Kurt Vonnegut. "Constellations: Hercules 'the Strongman'". The BBC (British Broadcasting Corporation). Retrieved 2010-11-14.
  15. ^ a b "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  16. ^ Knobel, E. B. (June 1895). "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket". Monthly Notices of the Royal Astronomical Society. 55 (8): 429. Bibcode:1895MNRAS..55..429K. doi:10.1093/mnras/55.8.429.
  17. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 25 日
  18. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Hercules
  19. ^ Wasatonic, Richard P. (January 1997). "Photoelectric Photometry of TX Psc, Alpha Her A, Omicron Cet, and RT Cyg". The Journal of the American Association of Variable Star Observers. 26 (1): 1–13. Bibcode:1997JAVSO..26....1W. Retrieved 18 December 2022.
  20. ^ a b Deutsch, Armin J. (March 1956). "The Circumstellar Envelope of Alpha Herculis". Astrophysical Journal. 123: 210–227. Bibcode:1956ApJ...123..210D. doi:10.1086/146152.
  21. ^ Benson, J. A.; Dyck, H. M.; Mason, W. L.; Howell, R. R.; Ridgway, S. T.; et al. (December 1991). "The infrared angular diameter of Alpha Herculis measured with a Michelson interferometer". Astronomical Journal. 102: 2091–2097. Bibcode:1991AJ....102.2091B. doi:10.1086/116033.
  22. ^ a b Percy, John R; Wilson, Joseph B; Henry, Gregory W (2001). "Long‐TermVRIPhotometry of Small‐Amplitude Red Variables. I. Light Curves and Periods". Publications of the Astronomical Society of the Pacific. 113 (786): 983. Bibcode:2001PASP..113..983P. doi:10.1086/322153.

External links edit

  • An Atlas of the Universe: Multiple Star Orbits
  • Upside down Hercules showing Alpha Herculisethi as the head:


December 04, 2023
alpha, herculis, herculis, abbreviated, alpha, also, designated, herculis, multiple, star, system, constellation, hercules, appearing, single, point, light, naked, resolvable, into, number, components, through, telescope, combined, apparent, magnitude, althoug. Alpha Herculis a Herculis abbreviated Alpha Her a Her also designated 64 Herculis is a multiple star system in the constellation of Hercules Appearing as a single point of light to the naked eye it is resolvable into a number of components through a telescope It has a combined apparent magnitude of 3 08 although the brightest component is variable in brightness Based on parallax measurements obtained during the Hipparcos mission it is approximately 360 light years 110 parsecs distant from the Sun a HerculisLocation of a Herculis circled Observation dataEpoch J2000 Equinox J2000Constellation HerculesARight ascension 17h 14m 38 853s 1 Declination 14 23 25 34 1 Apparent magnitude V 3 350 1 2 7 4 0 2 BRight ascension 17h 14m 39 181s 1 Declination 14 23 23 98 1 Apparent magnitude V 5 322 1 CharacteristicsAEvolutionary stage AGB 3 Spectral type M5 Ib II 3 U B color index 1 01 4 B V color index 1 45 4 Variable type SRc 2 BSpectral type G8III A9IV V 3 AstrometryProper motion m RA 7 32 5 mas yr Dec 36 07 5 mas yrParallax p 9 07 1 32 mas 5 Distanceapprox 360 ly approx 110 pc Absolute magnitude MV 2 3 6 1 8 2 8 7 DetailsAMass2 5 1 6 1 1 8 M Radius284 60 264 303 3 R Luminosity7 244 9 333 3 L Surface gravity log g 0 41 0 19 9 cgsTemperature3 155 3 365 3 KBaMass 2 5 3 M Luminosity126 3 L Temperature4 900 3 KBbMass 2 3 M Luminosity26 3 L Temperature7 350 3 KAge0 41 1 25 3 GyrOther designationsRas Algethi Rasalgethi a Her 64 Her BD 14 3207 HIP 84345 CCDM J17146 1424 AAVSO 1710 14 WDS J17146 1423 10 A HD 156014 HR 6406 SAO 102680B HD 156015 HR 6407 SAO 102681Database referencesSIMBADa HerAB Contents 1 System 2 Nomenclature 3 Properties 4 Notes 5 References 6 External linksSystem edit nbsp A view of Alpha Herculis in a small telescope The components A and B are resolved with angular separation of 4 64 in 2020 Alpha Herculis is a triple star system The primary brightest of the three stars designated a1 Herculis or a Herculis A is a pulsating variable star on the asymptotic giant branch AGB and is the second nearest AGB star after Mira The primary star forms a visual binary pair with a second star which is itself a spectroscopic binary 3 Alpha Herculis also forms the A and B components of a wider system designated WDS J17146 1423 with two additional faint visual companions designated WDS J17146 1423C and D 11 The two fainter stars are far more distant than the triple system 12 Nomenclature edita Herculis Latinised to Alpha Herculis is the system s Bayer designation a1 and a2 Herculis those of its two visible components 64 Herculis is the system s Flamsteed designation WDS J17146 1423 is the wider system s designation in the Washington Double Star Catalog The designations of Alpha Herculis main components as Alpha Herculis A and B and the wider system s four components as WDS J17146 1423A B C and D together with the spectroscopic pair Alpha Herculis Ba and Bb derive from the convention used by the Washington Multiplicity Catalog WMC for multiple star systems and adopted by the International Astronomical Union IAU 13 Alpha Herculis bore the traditional name Rasalgethi or Ras Algethi Arabic رأس الجاثي ra is al jathi Head of the Kneeler 14 Head comes from the fact that in antiquity Hercules was depicted upside down on maps of the constellation In 2016 the IAU organized a Working Group on Star Names WGSN 15 to catalog and standardize proper names for stars The WGSN approved the name Rasalgethi for the component Alpha Herculis A a1 on 30 June 2016 and it is now so included in the List of IAU approved Star Names 15 The term ra s al ja8iyy or Ras al Djathi appeared in the catalogue of stars in the Calendarium of Al Achsasi al Mouakket which was translated into Latin as Caput Ingeniculi 16 In Chinese astronomy Alpha Herculis is called 帝座 Pinyin Dizuo meaning Emperor s Seat The star is seen as marking itself and stands alone in the center of the Emperor s Seat asterism Heavenly Market enclosure see Chinese constellations 17 帝座 Dizuo was westernized into Ti Tso by R H Allen with the same meaning 18 Properties edit nbsp A light curve for Alpha Herculis A plotted from data published by Wasatonic 1997 19 Alpha Herculis A and B are more than 500 AU apart with an estimated orbital period of approximately 3600 years citation needed A presents as a relatively massive red bright giant but radial velocity measurements suggest a companion with a period of the order of a decade 11 B s two components are a primary yellow giant star and a secondary yellow white dwarf star in a 51 578 day orbit 20 Alpha Herculis A is an asymptotic giant branch AGB star a luminous red giant that has both hydrogen and helium shells around a degenerate carbon oxygen core It is the second nearest AGB star to the Sun 3 The angular diameter of the star has been measured with an interferometer as 34 0 8 mas or 0 034 arcseconds 21 At its estimated distance of 110 parsecs this corresponds to a radius of about 280 million kilometers or 170 million miles which is roughly 400 R or 1 87 AU a If Alpha Herculis were at the center of the Solar System its radius would extend past the orbit of Mars at 1 5 AU but not quite as far as the asteroid belt The red giant is estimated to have started its life with about 2 175 3 250 M 3 Alpha Herculis A has been specified as a standard star for the spectral class M5 Ib II 3 Like most type M stars near the end of their lives Alpha Herculis is experiencing a high degree of stellar mass loss creating a sparse gaseous envelope that extends at least 930 AU 20 It is a semiregular variable with complex changes in brightness with periods ranging from a few weeks to many years The most noticeable variations occur at timescales of 80 140 days and at 1 000 3 000 days The strongest detectable period is 128 days 22 The full range in brightness is from magnitude 2 7 to 4 0 2 but it usually varies over a much smaller range of around 0 6 magnitudes 22 Notes edit To determine Rasalgethi s radius in terms of solar units the calculations begin with the formula for angular diameter as follows d d R D R displaystyle begin smallmatrix delta frac d R D R end smallmatrix nbsp where d equals Rasalgethi s angular diameter in arcseconds dR the star s diameter in AU and DR the Distance from Earth in parsecs If one knows the angular diameter and the Distance then one can solve for dR as follows d R d D R 0 034 110 0 3 740 A U displaystyle begin smallmatrix d R delta cdot D R 0 034 cdot 110 0 3 740AU end smallmatrix nbsp To obtain Rasalgheti s radius R R d R 2 3 740 2 1 870 A U displaystyle begin smallmatrix R R left frac d R 2 right left frac 3 740 2 right 1 870AU end smallmatrix nbsp Converting into Solar units 1 AU 149 597 871 km and the mean radius of the Sun 696 000 km hence the calculation d B 1 87 A U 149 597 871 k m 696 000 k m 280 000 000 k m 402 R displaystyle begin smallmatrix d B left 1 87AU right left frac 149 597 871km 696 000km right 280 000 000km 402R odot end smallmatrix nbsp rounded References edit a b c d e f Hog E Fabricius C Makarov V V Urban S Corbin T Wycoff G Bastian U Schwekendiek P Wicenec A 2000 The Tycho 2 catalogue of the 2 5 million brightest stars Astronomy and Astrophysics 355 L27 Bibcode 2000A amp A 355L 27H doi 10 1888 0333750888 2862 ISBN 0333750888 a b c 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 a b c d e f g h i j k l m n o p q Moravveji Ehsan Guinan Edward F Khosroshahi Habib Wasatonic Rick 2013 The Age and Mass of the a Herculis Triple star System from a MESA Grid of Rotating Stars with 1 3 lt M M lt 8 0 The Astronomical Journal 146 6 148 arXiv 1308 1632 Bibcode 2013AJ 146 148M doi 10 1088 0004 6256 146 6 148 S2CID 117872505 a b Ducati J R 2002 VizieR Online Data Catalog Catalogue of Stellar Photometry in Johnson s 11 color system CDS ADC Collection of Electronic Catalogues 2237 Bibcode 2002yCat 2237 0D a b c van Leeuwen F November 2007 Hipparcos the New 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 Huang W Wallerstein G Stone M 2012 A catalogue of Paschen line profiles in standard stars Astronomy amp Astrophysics 547 A62 arXiv 1210 7893 Bibcode 2012A amp A 547A 62H doi 10 1051 0004 6361 201219804 S2CID 119286159 Reimers D 1977 On the absolute scale of mass loss in red giants I Circumstellar absorption lines in the spectrum of the visual companion of Alpha 1 HER Astronomy and Astrophysics 61 217 Bibcode 1977A amp A 61 217R Moravveji E Guinan E F Sobouti Y 2011 On the Mass and Evolutionary Status of the Bright Red AGB Supergiant a1 Herculis Why Galaxies Care About Agb Stars Ii Shining Examples and Common Inhabitants 445 163 Bibcode 2011ASPC 445 163M Schroder K P Cuntz M April 2007 A critical test of empirical mass loss formulas applied to individual giants and supergiants Astronomy and Astrophysics 465 2 593 601 arXiv astro ph 0702172 Bibcode 2007A amp A 465 593S doi 10 1051 0004 6361 20066633 S2CID 55901104 alf Her SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved 2010 09 26 a b Washington Double Star Catalog United States Naval Observatory Archived from the original on 2011 02 14 Retrieved 2018 07 10 Brown A G A et al Gaia collaboration August 2018 Gaia Data Release 2 Summary of the contents and survey properties Astronomy amp Astrophysics 616 A1 arXiv 1804 09365 Bibcode 2018A amp A 616A 1G doi 10 1051 0004 6361 201833051 Hessman F V Dhillon V S Winget D E Schreiber M R Horne K Marsh T R Guenther E Schwope A Heber U 2010 On the naming convention used for multiple star systems and extrasolar planets arXiv 1012 0707 astro ph SR Kurt Vonnegut Constellations Hercules the Strongman The BBC British Broadcasting Corporation Retrieved 2010 11 14 a b IAU Working Group on Star Names WGSN Retrieved 22 May 2016 Knobel E B June 1895 Al Achsasi Al Mouakket on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket Monthly Notices of the Royal Astronomical Society 55 8 429 Bibcode 1895MNRAS 55 429K doi 10 1093 mnras 55 8 429 in Chinese AEEA Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 6 月 25 日 Richard Hinckley Allen Star Names Their Lore and Meaning Hercules Wasatonic Richard P January 1997 Photoelectric Photometry of TX Psc Alpha Her A Omicron Cet and RT Cyg The Journal of the American Association of Variable Star Observers 26 1 1 13 Bibcode 1997JAVSO 26 1W Retrieved 18 December 2022 a b Deutsch Armin J March 1956 The Circumstellar Envelope of Alpha Herculis Astrophysical Journal 123 210 227 Bibcode 1956ApJ 123 210D doi 10 1086 146152 Benson J A Dyck H M Mason W L Howell R R Ridgway S T et al December 1991 The infrared angular diameter of Alpha Herculis measured with a Michelson interferometer Astronomical Journal 102 2091 2097 Bibcode 1991AJ 102 2091B doi 10 1086 116033 a b Percy John R Wilson Joseph B Henry Gregory W 2001 Long TermVRIPhotometry of Small Amplitude Red Variables I Light Curves and Periods Publications of the Astronomical Society of the Pacific 113 786 983 Bibcode 2001PASP 113 983P doi 10 1086 322153 External links editAn Atlas of the Universe Multiple Star Orbits Upside down Hercules showing Alpha Herculisethi as the head Hercules Portals nbsp Astronomy nbsp Stars nbsp Spaceflight nbsp Outer space nbsp Solar System Retrieved from https en wikipedia org w index php title Alpha Herculis amp oldid 1170292044, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.