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102 Herculis

From Wikipedia, the free encyclopedia
Star in the constellation Hercules
102 Herculis
Location of 102 Herculis (circled)
Observation data
Epoch J2000      Equinox J2000
ConstellationHercules
Right ascension18h 08m 45.49142s[1]
Declination+20° 48′ 52.4079″[1]
Apparent magnitude (V)4.37[2]
Characteristics
Spectral typeB2 IV[3][4] or B2 V[5][6]
B−Vcolor index−0.164±0.013[2]
Astrometry
Radial velocity (Rv)−14.9±0.6[2] km/s
Proper motion (μ)RA: −1.92[1]mas/yr
Dec.: −5.89[1]mas/yr
Parallax (π)3.56±0.19 mas[1]
Distance920 ± 50 ly
(280 ± 10 pc)
Absolute magnitude (MV)−2.87[2]
Details
Mass9.7±0.2[4] M☉
Luminosity3,631.92[2] L☉
Surface gravity (log g)3.54[7] cgs
Temperature22,420±1,440[8] K
Rotational velocity (v sin i)41[9] km/s
Age20.0±1.4[4] Myr
Other designations
Ramus,102 Her,BD+20°3674,FK5 3443,HD 166182,HIP 88886,HR 6787,SAO 85769,WDS J18088+2049[10]
Database references
SIMBADdata

102 Herculis, also namedRamus,[11] is a single[12]star in the northernconstellation ofHercules. It is visible to the naked eye as a faint, blue-white hued star with anapparent visual magnitude of 4.37.[2] Based uponparallax measurements, it is located around 920 light years away from the Sun.[1] The star is moving closer to the Earth with a heliocentricradial velocity of −15 km/s.[2]

Thestellar classification of this object matches a massive,earlyB-type star with aluminosity class of IV[3] or V,[5] corresponding to asubgiant ormain sequence star, respectively. It is 20[4] million years old with nearly ten[4] times themass of the Sun and is spinning with aprojected rotational velocity of 41 km/s.[9] The strength of thestellar magnetic field has been measured at(209.5±135.4)×10−4 T.[6] The star is radiating 3,632[2] times theSun's luminosity from itsphotosphere at aneffective temperature of 22,420 K.[8]

Etymology

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InChinese,帛度 (Bó Dù), meaningTextile Ruler, refers to an asterism consisting of 102 Herculis and95 Herculis.[13] Consequently, 102 Herculis itself is known as帛度二 (Bó Dù èr, English:the Second Star of Textile Ruler.)

This star, together with93 Herculis,95 Herculis, and109 Herculis, formed the now obsolete constellation ofCerberus, which was sometimes combined withRamus, the apple branch.[14] TheIAU Working Group on Star Names approved the name Ramus for 102 Herculis on 17 June 2025 and it is now so entered in the IAU Catalog of Star Names.[11] The WGSN avoided using the name Cerberus since it was already in use for the asteroid1865 Cerberus.[15]

References

[edit]
  1. ^abcdefvan Leeuwen, F. (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. ^abcdefghAnderson, 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. ^abLesh, Janet Rountree (December 1968), "The Kinematics of the Gould Belt: an Expanding Group?",Astrophysical Journal Supplement,17: 371,Bibcode:1968ApJS...17..371L,doi:10.1086/190179.
  4. ^abcdeTetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun",Monthly Notices of the Royal Astronomical Society,410 (1):190–200,arXiv:1007.4883,Bibcode:2011MNRAS.410..190T,doi:10.1111/j.1365-2966.2010.17434.x,S2CID 118629873.
  5. ^abEggen, Olin J. (1961), "Space motions and distribution of the apparently bright B-type stars",Royal Observatory Bulletins,41:245–287,Bibcode:1961RGOB...41..245E.
  6. ^abBychkov, V. D.; et al. (August 2003), "Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars",Astronomy and Astrophysics,407 (2):631–642,arXiv:astro-ph/0307356,Bibcode:2003A&A...407..631B,doi:10.1051/0004-6361:20030741,S2CID 14184105.
  7. ^Lyubimkov, L. S.; et al. (June 2004), "Surface abundances of light elements for a large sample of early B-type stars - III. An analysis of helium lines in spectra of 102 stars",Monthly Notices of the Royal Astronomical Society,351 (2):745–767,Bibcode:2004MNRAS.351..745L,doi:10.1111/j.1365-2966.2004.07825.x.
  8. ^abZorec, J.; et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into Teff",Astronomy and Astrophysics,501 (1):297–320,arXiv:0903.5134,Bibcode:2009A&A...501..297Z,doi:10.1051/0004-6361/200811147,S2CID 14969137.
  9. ^abSimón-Díaz, S.; et al. (2017), "The IACOB project . III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars",Astronomy and Astrophysics,597: A22,arXiv:1608.05508,Bibcode:2017A&A...597A..22S,doi:10.1051/0004-6361/201628541,S2CID 3478126.
  10. ^"102 Her".SIMBAD.Centre de données astronomiques de Strasbourg. Retrieved2019-06-17.
  11. ^ab"IAU Catalog of Star Names". Retrieved17 June 2025.
  12. ^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.
  13. ^"Bodu (帛度)".All Skies Encyclopaedia.IAU Working Group on Star Names. Retrieved17 June 2025.
  14. ^Ian Ridpath's Star Tales - Cerberus
  15. ^"Ramus".All Skies Encyclopaedia.IAU Working Group on Star Names. Retrieved17 June 2025.
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