109 Herculis

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109 Herculis
Observation data
Epoch J2000        Equinox J2000
Constellation Hercules
Right ascension 18h 23m 41.88971s [1]
Declination +21° 46′ 11.1096″ [1]
Apparent magnitude  (V)3.84 [2]
Characteristics
Evolutionary stage horizontal branch [3]
Spectral type K2IIIab [4]
B−V color index 1.168±0.005 [5]
Astrometry
Radial velocity (Rv)−57.55±0.27 [6] km/s
Proper motion (μ)RA: +195.971 mas/yr [1]
Dec.: −243.234 mas/yr [1]
Parallax (π)26.9636±0.1049  mas [1]
Distance 121.0 ± 0.5  ly
(37.1 ± 0.1  pc)
Absolute magnitude  (MV)+0.87 [7]
Details [8]
Mass 1.05±0.18  M☉
Radius 11.55+0.20
−0.19  R☉
Luminosity 52.4±3  L☉
Surface gravity (log g)2.24  cgs
Temperature 4,569±60  K
Metallicity [Fe/H]−0.06  dex
Rotational velocity (v sin i)4.4 [6]  km/s
Age 6.39±2.71  Gyr
Other designations
Tusizuo, 109 Her, BD+21°3411, FK5 690, HD 169414, HIP 90139, HR 6895, SAO 86003, WDS J18237+2146 [9]
Database references
SIMBAD data

109 Herculis, also named Tusizuo, [10] is a single [11] star in the northern constellation of Hercules. It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 3.84. [2] The star is located around 121 light-years (37 parsecs) distant, based on parallax. [1] It is moving closer to the Earth with a heliocentric radial velocity of −58 km/s, [6] and may come as close as 81 light-years away in around 328,000 years. [5]

This is an aging giant star with a stellar classification of K2IIIab. [4] It is a red clump giant, [3] meaning it is on the horizontal branch and is generating energy through helium fusion at its core. The star is roughly six billion years old with slightly more mass than the Sun. [8] With the supply of hydrogen at its core exhausted, it has expanded to nearly 12 times the Sun's radius. [8] The star is radiating 52 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,569 K. [8]

Nomenclature

In Chinese astronomy, 109 Herculis is one of two stars in the asterism Tú Sì (屠肆, "Butcher's Shop"). It is named Tusizuo, meaning the left star in Tusi. The IAU Working Group on Star Names approved the name Tusizuo for this star on 17 June 2025 and it is now so entered in the IAU Catalog of Star Names. [10] The name Tusi was already in use for the asteroid 10269 Tusi, named after a Persian astronomer. [10]

This star, together with 93 Herculis, 95 Herculis, and 102 Herculis, formed Cerberus, the obsolete constellation. [12]

References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 J. R., Ducati (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.
  3. 1 2 Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society , 408 (2): 1225–1232, arXiv: 1006.3857 , Bibcode:2010MNRAS.408.1225P, doi: 10.1111/j.1365-2966.2010.17195.x , S2CID   44228180.
  4. 1 2 Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  5. 1 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.
  6. 1 2 3 Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi: 10.1088/0004-6256/135/1/209 .
  7. ↑ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics, 430: 303–311, arXiv: astro-ph/0409683 , Bibcode:2005A&A...430..303C, doi:10.1051/0004-6361:20041440, S2CID   12136256.
  8. 1 2 3 4 Baines, Ellyn K.; et al. (2018), "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.
  9. ↑ "109 Her". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-06-18.
  10. 1 2 3 "IAU Catalog of Star Names" . Retrieved 17 June 2025.
  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 Star Tales - Cerberus
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