102 Herculis

102 Herculis is a single^[11] star in the northern constellation of Hercules. It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.37.^[2] Based upon parallax measurements, it is located around 920 light years away from the Sun.^[1] The star is moving closer to the Earth with a heliocentric radial velocity of −15 km/s.^[2]

102 Herculis

Observation data Epoch J2000      Equinox J2000
Constellation	Hercules
Right ascension	18h 08m 45.49142s[1]
Declination	+20° 48′ 52.4079″[1]
Apparent magnitude (V)	4.37[2]
Characteristics
Spectral type	B2 IV[3][4] or B2 V[5][6]
B−V color 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]
Distance	920 ± 50 ly (280 ± 10 pc)
Absolute magnitude (MV)	−2.87[2]
Details
Mass	9.7±0.2[4] M☉
Luminosity	3,631.92[2] L☉
Surface gravity (log g)	3.54[7] cgs
Temperature	22,420±1,440[8] K
Rotational velocity (v sin i)	41[9] km/s
Age	20.0±1.4[4] Myr
Other designations
102 Her, BD+20°3674, FK5 3443, HD 166182, HIP 88886, HR 6787, SAO 85769, WDS J18088+2049[10]
Database references
SIMBAD	data

The stellar classification of this object matches a massive, early B-type star with a luminosity class of IV^[3] or V,^[5] corresponding to a subgiant or main sequence star, respectively. It is 20^[4] million years old with nearly ten^[4] times the mass of the Sun and is spinning with a projected rotational velocity of 41 km/s.^[9] The strength of the stellar magnetic field has been measured at (209.5±135.4)×10⁻⁴ T.^[6] The star is radiating 3,632^[2] times the Sun's luminosity from its photosphere at an effective temperature of 22,420 K.^[8]

Etymology

In Chinese, 帛度 (Bó Dù), meaning Textile Ruler, refers to an asterism consisting of 102 Herculis and 95 Her^[12].Consequently, 102 Herculis itself is known as 帛度二 (Bó Dù èr, English: the Second Star of Textile Ruler.)

This star, together with 93 Her, 95 Her, and 109 Her, formed the now obsolete constellation of Cerberus.^[13]

References

1. van 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. 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. Lesh, 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. Tetzlaff, 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. Eggen, 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. Bychkov, 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. Zorec, J.; et al. (July 2009), "Fundamental parameters of B supergiants from the BCD system. I. Calibration of the (λ_1, D) parameters into T_eff", Astronomy and Astrophysics, 501 (1): 297–320, arXiv:0903.5134, Bibcode:2009A&A...501..297Z, doi:10.1051/0004-6361/200811147, S2CID 14969137.
9. Simón-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. Retrieved 2019-06-17.
11. 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.
12. Ian Ridpath's Startales - Hercules
13. Ian Ridpath's Star Tales - Cerberus