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Theta Herculis

Star in the constellation Hercules

Summary

Star in the constellation Hercules

| b-v=+1.35 | u-b=+1.40 | r-i=+0.63

Theta Herculis is a single, variable star in the northern constellation of Hercules. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 3.851. Based upon parallax measurements, it is located around 750 light years away from the Sun. The star is advancing toward the Earth with a heliocentric radial velocity of –28 km/s.

This is an aging K-type bright giant with a stellar classification of K1IIaCN2, where the suffix notation indicates a strong overabundance of CN in the spectrum. The brightness variations of this star was first noticed in 1935 by M. Fedtke and confirmed by Erich Przybyllok and Kurt Walter the same year. French astronomer Paul Muller then classified Theta Herculis as an irregular variable with a range of magnitudes between 3.7 and 4.1 and a periodicity of roughly 8–9 days.

The star is about 130 million years old with 5.89 times the mass of the Sun. With the hydrogen at its core exhausted, the star has expanded to 82 times the Sun's radius. It is radiating 2,400 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,448 K.

Nomenclature and etymology

θ Herculis is the Bayer designation, Latinised to Theta Herculis, abbreviated to θ Her or Theta Her.

In the Calendarium of Al Achsasi Al Mouakket, this star was designated Rekbet al Jathih al Aisr, which was translated into Latin as Genu Sinistrum Ingeniculi, meaning the left knee of the kneeling man.{{cite journal

In Chinese, 天紀 (Tiān Jì), meaning Celestial Discipline, refers to an asterism consisting of θ Herculis, ξ Coronae Borealis, ζ Herculis, ε Herculis, 59 Herculis, 61 Herculis, 68 Herculis and HD 160054. Consequently, the Chinese name for θ Herculis itself is 天紀九 (Tiān Jì jiǔ, .) It was also Tien Ke, Heaven's Record.

References

References

  1. "tet Her".
  2. {{in lang. zh ''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.
  3. {{in lang. zh [http://aeea.nmns.edu.tw/2006/0606/ap060626.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 26 日] {{Webarchive. link. (2011-05-22)
  4. "Allen's Star Names - Hercules".
  5. van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
  6. (March 2008). "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars". The Astronomical Journal.
  7. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". SIMBAD.
  8. (January 1935). "Sur la variabilité de θ Herculis". ADS.
  9. (2024-02-01). "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version". Astronomy and Astrophysics.
  10. (December 1990). "High-resolution spectroscopic survey of 671 GK giants". STI.
  11. "Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". [[Centre de Données astronomiques de Strasbourg]].
  12. (2015). "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity". Astronomy & Astrophysics.
  13. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics.
  14. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series.
Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

k-type-bright-giants suspected-variables hercules-(constellation) bayer-objects durchmusterung-objects flamsteed-objects henry-draper-catalogue-objects hipparcos-objects bright-star-catalogue-objects
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