Astronomy:Xi Herculis

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Short description: Star in the constellation Hercules
Xi Herculis
Location of ξ Herculis (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Hercules
Right ascension  17h 57m 45.88567s[1]
Declination +29° 14′ 52.3660″[1]
Apparent magnitude (V) 3.70[2]
Characteristics
Evolutionary stage red clump[3]
Spectral type G8 III[4]
U−B color index +0.66[2]
B−V color index +0.93[2]
Astrometry
Radial velocity (Rv)−1.65±0.17[5] km/s
Proper motion (μ) RA: 81.919[1] mas/yr
Dec.: −18.962[1] mas/yr
Parallax (π)23.8544 ± 0.1068[1] mas
Distance136.7 ± 0.6 ly
(41.9 ± 0.2 pc)
Absolute magnitude (MV)+0.62[6]
Details
Mass2.01[7] M☉
Radius9.94±0.09[8] R☉
Luminosity57.2±2.1[8] L☉
Surface gravity (log g)2.87±0.09[9] cgs
Temperature5,032±48[8] K
Metallicity [Fe/H]+0.09±0.04[9] dex
Rotation67[3] d
Rotational velocity (v sin i)2.8[5] km/s
Age2.48[7] Gyr
Other designations
ξ Her, 92 Her, BD+29°3156, HD 163993, HIP 87933, HR 6703, SAO 85590[10]
Database references
SIMBADdata

Xi Herculis is a solitary[11] star located within the northern constellation of Hercules. The star is visible to the naked eye with an apparent visual magnitude of 3.70.[2] Based upon an annual parallax shift of 23.85 mas as seen from Earth, it is located 137 light years from the Sun.[1] At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.05 due to interstellar dust. It is a suspected member of the Sirius stream of co-moving stars.[12]

ξ Herculis in optical light
File:XiHerLightCurve.png
A light curve for Xi Herculis, plotted from Hipparcos data[13]

This is an evolved G-type giant star with a stellar classification of G8 III.[4] It is a red clump star, which means it is on the horizontal branch and generating energy through the thermonuclear fusion of hydrogen at its core. The star is emitting X-rays with a luminosity of 3.03×1030 erg s−1 in the 0.3–10 keV band.[3] It has twice[7] the mass of the Sun but, at the age of two and a half billion years,[7] it has expanded to 10 times the Sun's radius. The star is radiating 57 times the solar luminosity from its photosphere at an effective temperature of 5,032 K.[8]

Xi Herculis was discovered to be a variable star when the Hipparcos data was analyzed.[14] It is a semiregular variable star, oscillating in brightness by 3 hundredths of a magnitude, over a period of 120.8 days.[15]

Chinese name

In R. H. Allen's book Star Names: Their Lore and Meaning, this star, together with ν Her and 99 Her (b Herculis) represent the state of Zhongshan (or Chung Shan, "the Middle Mountain"),[16] but in Chinese literature, that name is applied to ο Her.[17]

Markov 1, the mini teapot

One third of a degree to the north-northwest of Xi Herculis is the location of a telescopic asterism in the shape of a teapot. This teapot (Markov 1) could be seen as a somewhat twisted small equivalent of the large and easy to recognize teapot asterism in the constellation Sagittarius.[citation needed]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M. 
  3. ↑ 3.0 3.1 3.2 Gondoin, P. (December 2005), "The relation between X-ray activity and rotation in intermediate-mass G giants", Astronomy and Astrophysics 444 (2): 531–538, doi:10.1051/0004-6361:20053567, Bibcode: 2005A&A...444..531G. 
  4. ↑ 4.0 4.1 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics 11 (1): 29, doi:10.1146/annurev.aa.11.090173.000333, Bibcode: 1973ARA&A..11...29M. 
  5. ↑ 5.0 5.1 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, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M. 
  6. ↑ Böhm-Vitense, Erika et al. (December 2000), "Ultraviolet Emission Lines in BA and Non-BA Giants", The Astrophysical Journal 545 (2): 992–999, doi:10.1086/317850, Bibcode: 2000ApJ...545..992B. 
  7. ↑ 7.0 7.1 7.2 7.3 Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal 150 (3): 23, doi:10.1088/0004-6256/150/3/88, 88, Bibcode: 2015AJ....150...88L. 
  8. ↑ 8.0 8.1 8.2 8.3 Baines, Ellyn K.; Thomas Armstrong, J.; Clark, James H.; Gorney, Jim; Hutter, Donald J.; Jorgensen, Anders M.; Kyte, Casey; Mozurkewich, David et al. (2021). "Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer". The Astronomical Journal 162 (5): 198. doi:10.3847/1538-3881/ac2431. Bibcode: 2021AJ....162..198B. 
  9. ↑ 9.0 9.1 Prugniel, Ph. et al. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics 531: A165, doi:10.1051/0004-6361/201116769, Bibcode: 2011A&A...531A.165P. 
  10. ↑ "ksi Her". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=ksi+Her. 
  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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E. 
  12. ↑ Famaey, B. et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics 430 (1): 165–186, doi:10.1051/0004-6361:20041272, Bibcode: 2005A&A...430..165F. 
  13. ↑ "/ftp/cats/more/HIP/cdroms/cats". Strasbourg astronomical Data Center. https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats. 
  14. ↑ Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Frolov, M. S.; Antipin, S. V.; Kireeva, N. N.; Pastukhova, E. N. (January 1999). "The 74th Special Name-list of Variable Stars". Information Bulletin on Variable Stars 4659. Bibcode: 1999IBVS.4659....1K. https://ibvs.konkoly.hu/pub/ibvs/4601/4659.pdf. Retrieved 23 December 2024. 
  15. ↑ "ksi Her". AAVSO. https://www.aavso.org/vsx/index.php?view=detail.top&oid=15893. 
  16. ↑ Allen, R. H. (1963), Star Names, Their Lore and Meaning, Dover, p. 246, https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Hercules*.html, retrieved 2017-04-11. 
  17. ↑ Script error: The function "in_lang" does not exist. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 6 日



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