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Tau Herculis

January 01, 1970

Tau Herculis, a name Latinized from τ Herculis, is a variable star in the northern constellation of Hercules. It has a blue-white hue and is visible to the naked eye at night with an apparent visual magnitude that fluctuates around 3.91.[2] The star is located at a distance of approximately 307 light years from the Sun based on parallax,[1] but it is drifting closer with a radial velocity of −16 km/s.[2]

Tau Herculis

Historical depiction of the constellation Hercules with τ, bottom left, as the "northern knee"
Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
Right ascension 16h 19m 44.43666s[1]
Declination 46° 18′ 48.1123″[1]
Apparent magnitude (V) 3.91[2] 3.83 to 3.86[3]
Characteristics
Evolutionary stage Main sequence[4]
Spectral type B5 IV[5]
U−B color index −0.569[2]
B−V color index −0.151±0.009[2]
Variable type SPB[3]
Astrometry
Radial velocity (Rv)−15.5±0.5[2] km/s
Proper motion (μ) RA: −13.33[1] mas/yr
Dec.: 38.48[1] mas/yr
Parallax (π)10.61 ± 0.11 mas[1]
Distance307 ± 3 ly
(94.3 ± 1.0 pc)
Absolute magnitude (MV)−0.96[2]
Details
Mass4.01[6] M☉
Radius3.55±0.19 R☉[7]
3.80±0.25[8] R☉
Luminosity574[2] L☉
Surface gravity (log g)4.02±0.05[7] cgs
Temperature15,615±301[7] K
Metallicity [Fe/H]0.15[9] dex
Rotational velocity (v sin i)32[6] km/s
Age26[6] Myr
Other designations
Rukbalgethi Shemali, τ Her, 22 Her, BD+46°2169, FK5 608, GC 21987, HD 147394, HIP 79992, HR 6092, SAO 46028, CCDM J16197+4619A[10]
Database references
SIMBADdata
A light curve for Tau Herculis, plotted from TESS data[11]

The stellar classification of Tau Hercules is B5 IV,[5] and it serves as a standard spectrum in the modern Morgan–Keenan (MK) classification.[12] It is estimated to be just 26 million years old with a relatively low projected rotational velocity of 32 km/s.[6] Slowly rotating B-type stars are often chemically peculiar, so the mostly normal spectra of this star suggests we may be viewing it from near pole-on.[13] The abundance of most heavier elements in this star are about 85% of those in the Sun.[14] The star has four times the mass of the Sun[6] and around 3.8[8] times the Sun's radius. On average, it is radiating 574[2] times the luminosity of the Sun from its photosphere at an effective temperature of 15,615 K.[7]

During the Hipparcos mission,[4] Tau Hercules was discovered to be a variable star of the slowly pulsating B-type. These are mid-B main sequence stars that vary with a period of about a day;[4] the brightness of Tau Hercules varies by 0.03 magnitude[3] over a period of 1.24970±0.00008 days. The radial velocity of the star varies at a different rate than the photometric period, with the object showing both radial and non-radial pulsation modes.[4][15]

Historical significance and etymology edit

 
The path of the north celestial pole among the stars due to the precession.

Tau Herculis is located within 1° of the precessional path traced across the celestial sphere by the Earth's North pole. It could have served the northern pole star around the year 7400 BCE, a phenomenon which is expected to reoccur in the year 18,400 due to precession.[13]

Preceded by Pole Star Succeeded by
Iota Herculis 18,400 AD Alpha Draconis

Its traditional name, Rukbalgethi Shemali, is of Arabic origin and shares certain etymological characteristics with the stars Ruchbah and Zubeneschamali, signifying Hercules' "northern knee".[16][better source needed]

In Chinese, 七公 (Qī Gōng), meaning Seven Excellencies, refers to an asterism consisting of τ Herculis, 42 Herculis, φ Herculis, χ Herculis, ν1 Boötis, μ1 Boötis and δ Boötis.[17] Consequently, the Chinese name for τ Herculis itself is 七公二 (Qī Gōng èr, English: the Second Star of Seven Excellencies.)[18]

References edit

  1. ^ a b c d e f van 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.
  2. ^ a b c d e f g h i Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. ^ a b c Samus', N. N; et al. (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  4. ^ a b c d Masuda, Seiji; Hirata, Ryuko (April 2000), "Line-profile variation in tau Herculis", Astronomy and Astrophysics, 356: 209–212, Bibcode:2000A&A...356..209M.
  5. ^ a b Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333.
  6. ^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  7. ^ a b c d Fitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry", The Astronomical Journal, 129 (3): 1642–1662, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855, S2CID 119512018.
  8. ^ a b Gordon, Kathryn D.; et al. (2019), "Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array", The Astrophysical Journal, 873 (1): 91, Bibcode:2019ApJ...873...91G, doi:10.3847/1538-4357/ab04b2, S2CID 125181833.
  9. ^ Smith, K. C.; Dworetsky, M. M. (1993), "Elemental Abundances in Normal Late B-Stars and Hgmn-Stars from Co-Added IUE Spectra - Part One - Iron Peak Elements", Astronomy and Astrophysics, 274 (2): 335, Bibcode:1993A&A...274..335S
  10. ^ "* tau Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-06-10.
  11. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 24 September 2022.
  12. ^ Garcia, B. (June 1989), "A list of MK standard stars", Bulletin d'Information du Centre de Donnees Stellaires, 36: 27, Bibcode:1989BICDS..36...27G.
  13. ^ a b Kaler, James B., "TAU HER (Tau Herculis)", Stars, University of Illinois, retrieved 2018-04-27.
  14. ^ Adelman, Saul J.; et al. (June 2001), "Elemental abundance analyses with DAO spectrograms. XXV. The superficially normal B and A stars alpha Draconis, tau Herculis, gamma Lyrae, and HR 7926", Astronomy and Astrophysics, 371 (3): 1078–1083, Bibcode:2001A&A...371.1078A, doi:10.1051/0004-6361:20010408
  15. ^ Briquet, M.; et al. (April 2003), "Spectroscopic mode identification for the slowly pulsating B star HD 147394", Astronomy and Astrophysics, 401: 281–288, Bibcode:2003A&A...401..281B, doi:10.1051/0004-6361:20030086.
  16. ^ Kurt Vonnegut. "Constellations: Hercules 'the Strongman'". The BBC (British Broadcasting Corporation). Retrieved 2010-11-14.
  17. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  18. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 26 日

January 01, 1970
herculis, name, latinized, from, herculis, variable, star, northern, constellation, hercules, blue, white, visible, naked, night, with, apparent, visual, magnitude, that, fluctuates, around, star, located, distance, approximately, light, years, from, based, pa. Tau Herculis a name Latinized from t Herculis is a variable star in the northern constellation of Hercules It has a blue white hue and is visible to the naked eye at night with an apparent visual magnitude that fluctuates around 3 91 2 The star is located at a distance of approximately 307 light years from the Sun based on parallax 1 but it is drifting closer with a radial velocity of 16 km s 2 Tau HerculisHistorical depiction of the constellation Hercules with t bottom left as the northern knee Observation dataEpoch J2000 Equinox J2000 Constellation Hercules Right ascension 16h 19m 44 43666s 1 Declination 46 18 48 1123 1 Apparent magnitude V 3 91 2 3 83 to 3 86 3 Characteristics Evolutionary stage Main sequence 4 Spectral type B5 IV 5 U B color index 0 569 2 B V color index 0 151 0 009 2 Variable type SPB 3 AstrometryRadial velocity Rv 15 5 0 5 2 km sProper motion m RA 13 33 1 mas yr Dec 38 48 1 mas yrParallax p 10 61 0 11 mas 1 Distance307 3 ly 94 3 1 0 pc Absolute magnitude MV 0 96 2 DetailsMass4 01 6 M Radius3 55 0 19 R 7 3 80 0 25 8 R Luminosity574 2 L Surface gravity log g 4 02 0 05 7 cgsTemperature15 615 301 7 KMetallicity Fe H 0 15 9 dexRotational velocity v sin i 32 6 km sAge26 6 Myr Other designationsRukbalgethi Shemali t Her 22 Her BD 46 2169 FK5 608 GC 21987 HD 147394 HIP 79992 HR 6092 SAO 46028 CCDM J16197 4619A 10 Database referencesSIMBADdata A light curve for Tau Herculis plotted from TESS data 11 The stellar classification of Tau Hercules is B5 IV 5 and it serves as a standard spectrum in the modern Morgan Keenan MK classification 12 It is estimated to be just 26 million years old with a relatively low projected rotational velocity of 32 km s 6 Slowly rotating B type stars are often chemically peculiar so the mostly normal spectra of this star suggests we may be viewing it from near pole on 13 The abundance of most heavier elements in this star are about 85 of those in the Sun 14 The star has four times the mass of the Sun 6 and around 3 8 8 times the Sun s radius On average it is radiating 574 2 times the luminosity of the Sun from its photosphere at an effective temperature of 15 615 K 7 During the Hipparcos mission 4 Tau Hercules was discovered to be a variable star of the slowly pulsating B type These are mid B main sequence stars that vary with a period of about a day 4 the brightness of Tau Hercules varies by 0 03 magnitude 3 over a period of 1 24970 0 00008 days The radial velocity of the star varies at a different rate than the photometric period with the object showing both radial and non radial pulsation modes 4 15 Historical significance and etymology edit nbsp The path of the north celestial pole among the stars due to the precession Tau Herculis is located within 1 of the precessional path traced across the celestial sphere by the Earth s North pole It could have served the northern pole star around the year 7400 BCE a phenomenon which is expected to reoccur in the year 18 400 due to precession 13 Preceded by Pole Star Succeeded by Iota Herculis 18 400 AD Alpha Draconis Its traditional name Rukbalgethi Shemali is of Arabic origin and shares certain etymological characteristics with the stars Ruchbah and Zubeneschamali signifying Hercules northern knee 16 better source needed In Chinese 七公 Qi Gōng meaning Seven Excellencies refers to an asterism consisting of t Herculis 42 Herculis f Herculis x Herculis n1 Bootis m1 Bootis and d Bootis 17 Consequently the Chinese name for t Herculis itself is 七公二 Qi Gōng er English the Second Star of Seven Excellencies 18 References edit a b c d e f 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 d e f g h i Anderson E Francis Ch 2012 XHIP An extended hipparcos compilation Astronomy Letters 38 5 331 arXiv 1108 4971 Bibcode 2012AstL 38 331A doi 10 1134 S1063773712050015 S2CID 119257644 a b c Samus N N et al 2017 General catalogue of variable stars Version GCVS 5 1 Astronomy Reports 61 1 80 Bibcode 2017ARep 61 80S doi 10 1134 S1063772917010085 S2CID 125853869 a b c d Masuda Seiji Hirata Ryuko April 2000 Line profile variation in tau Herculis Astronomy and Astrophysics 356 209 212 Bibcode 2000A amp A 356 209M a b Morgan W W Keenan P C 1973 Spectral Classification Annual Review of Astronomy and Astrophysics 11 29 Bibcode 1973ARA amp A 11 29M doi 10 1146 annurev aa 11 090173 000333 a b c d e David Trevor J Hillenbrand Lynne A 2015 The Ages of Early Type Stars Stromgren Photometric Methods Calibrated Validated Tested and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets The Astrophysical Journal 804 2 146 arXiv 1501 03154 Bibcode 2015ApJ 804 146D doi 10 1088 0004 637X 804 2 146 S2CID 33401607 a b c d Fitzpatrick E L Massa D March 2005 Determining the Physical Properties of the B Stars II Calibration of Synthetic Photometry The Astronomical Journal 129 3 1642 1662 arXiv astro ph 0412542 Bibcode 2005AJ 129 1642F doi 10 1086 427855 S2CID 119512018 a b Gordon Kathryn D et al 2019 Angular Sizes Radii and Effective Temperatures of B type Stars from Optical Interferometry with the CHARA Array The Astrophysical Journal 873 1 91 Bibcode 2019ApJ 873 91G doi 10 3847 1538 4357 ab04b2 S2CID 125181833 Smith K C Dworetsky M M 1993 Elemental Abundances in Normal Late B Stars and Hgmn Stars from Co Added IUE Spectra Part One Iron Peak Elements Astronomy and Astrophysics 274 2 335 Bibcode 1993A amp A 274 335S tau Her SIMBAD Centre de donnees astronomiques de Strasbourg Retrieved 2010 06 10 MAST Barbara A Mikulski Archive for Space Telescopes Space Telescope Science Institute retrieved 24 September 2022 Garcia B June 1989 A list of MK standard stars Bulletin d Information du Centre de Donnees Stellaires 36 27 Bibcode 1989BICDS 36 27G a b Kaler James B TAU HER Tau Herculis Stars University of Illinois retrieved 2018 04 27 Adelman Saul J et al June 2001 Elemental abundance analyses with DAO spectrograms XXV The superficially normal B and A stars alpha Draconis tau Herculis gamma Lyrae and HR 7926 Astronomy and Astrophysics 371 3 1078 1083 Bibcode 2001A amp A 371 1078A doi 10 1051 0004 6361 20010408 Briquet M et al April 2003 Spectroscopic mode identification for the slowly pulsating B star HD 147394 Astronomy and Astrophysics 401 281 288 Bibcode 2003A amp A 401 281B doi 10 1051 0004 6361 20030086 Kurt Vonnegut Constellations Hercules the Strongman The BBC British Broadcasting Corporation Retrieved 2010 11 14 in Chinese 中國星座神話 written by 陳久金 Published by 台灣書房出版有限公司 2005 ISBN 978 986 7332 25 7 in Chinese AEEA Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 6 月 26 日 Retrieved from https en wikipedia org w index php title Tau Herculis amp oldid 1223661525, wikipedia, wiki, book, books, library,

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