G Herculis

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G Herculis
30HerLightCurve.png
A light curve for g Herculis, plotted from Hipparcos data [1]
Observation data
Epoch J2000        Equinox J2000
Constellation Hercules
Right ascension 16h 28m 38.54859s [2]
Declination +41° 52′ 54.0406″ [2]
Apparent magnitude  (V)4.3 - 6.3 [3]
Characteristics
Evolutionary stage AGB [4]
Spectral type M6− III [5]
B−V color index 1.289±0.024 [6]
Variable type SRb [3]
Astrometry
Radial velocity (Rv)1.49±0.38 [6] km/s
Proper motion (μ)RA: +30.16 [2] mas/yr
Dec.: −5.14 [2] mas/yr
Parallax (π)9.21±0.18  mas [2]
Distance 354 ± 7  ly
(109 ± 2  pc)
Absolute magnitude  (MV)−0.41 [7]
Orbit [4]
Period (P)843.7±21.1 d
Eccentricity (e)0.37±0.11
Periastron epoch (T)2,451,918.2±43.9  HJD
Argument of periastron (ω)
(secondary)		246±21°
Semi-amplitude (K1)
(primary)		2.3±0.3 km/s
Details
g Her A
Mass 1.65±0.30 [8]   M☉
Radius 230 [9]   R☉
Luminosity 5,395 [9]   L☉
Surface gravity (log g)0.20 [10]   cgs
Temperature 3,263±23 [9]   K
Metallicity [Fe/H]−0.01 [10]   dex
Other designations
g Her, 30 Her, BD+42°2714, FK5 3303, HD 148783, HIP 80704, HR 6146, SAO 46108 [11]
Database references
SIMBAD data

g Herculis is a binary star [12] system in the northern constellation of Hercules, which makes part of a wide triple star system. It has the Flamsteed designation 30 Herculis, while g Herculis is the Bayer designation. This system is visible to the naked eye as a faint, red-hued point of light. Based upon a measured parallax of 9.2  mas , it is located around 354  light years away from the Sun. The system is moving further from the Earth with a heliocentric radial velocity of 1.5 km/s. [6]

Characteristics

This is a single-lined spectroscopic binary with an orbital period of 2.310 years and an eccentricity of 0.37. [4] The visible component is an aging red giant on the asymptotic giant branch [4] with a stellar classification of M6− III. [5] According to Samus et al. (2017), it is a semiregular variable of subtype SRb, which ranges between visual magnitudes 4.3 and 6.3 over 89.2 days. [3] [13] It displays cyclical periods of 62.3, 89.5, and 888.9 days. [4] The star is surrounded by a circumstellar dust shell that seems primarily composed of oxides of iron, magnesium, and aluminium, rather than silicates. [14]

In addition to the spectroscopic pair, there is a much wider star sharing similar proper motion and distance. It is a so-called proper motion companion. This star has a projected separation of 1,060  astronomical units from the inner pair. Its mass is estimated at 0.4 solar masses, and its apparent magnitude is much fainter than that of g Herculis. [15]

References

  1. ↑ "Light Curve", Hipparcos ESA, ESA, retrieved 20 September 2022.
  2. 1 2 3 4 5 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.
  3. 1 2 3 Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID   125853869.
  4. 1 2 3 4 5 Hinkle, Kenneth H.; et al. (February 2002), "Velocity Observations of Multiple-Mode Asymptotic Giant Branch Variable Stars", The Astronomical Journal, 123 (2): 1002–1012, Bibcode:2002AJ....123.1002H, doi: 10.1086/338314
  5. 1 2 Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245–266, Bibcode:1989ApJS...71..245K, doi:10.1086/191373, S2CID   123149047.
  6. 1 2 3 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.
  7. ↑ Schiavon, Ricardo P. (July 2007), "Population Synthesis in the Blue. IV. Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations", The Astrophysical Journal Supplement Series, 171 (1): 146–205, arXiv: astro-ph/0611464 , Bibcode:2007ApJS..171..146S, doi:10.1086/511753, S2CID   13946698.
  8. ↑ Halabi, Ghina M.; Eid, Mounib El (August 2015), "Exploring masses and CNO surface abundances of red giant stars", Monthly Notices of the Royal Astronomical Society, 451 (3): 2957–2967, arXiv: 1507.01517 , Bibcode:2015MNRAS.451.2957H, doi: 10.1093/mnras/stv1141 , S2CID   118707332.
  9. 1 2 3 Ayres, Thomas (2023-05-01), "In the Trenches of the Solar-Stellar Connection. VII. Wilson-Bappu 2022", The Astrophysical Journal Supplement Series, 266 (1): 6, Bibcode:2023ApJS..266....6A, doi: 10.3847/1538-4365/acb535 , ISSN   0067-0049 g Herculis' database entry at VizieR.
  10. 1 2 Ramírez, Solange V.; et al. (2000), "Stellar Iron Abundances at the Galactic Center", The Astrophysical Journal, 537 (1): 205–220, arXiv: astro-ph/0002062 , Bibcode:2000ApJ...537..205R, doi:10.1086/309022, S2CID   14713550.
  11. ↑ "g Her". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2019-06-13.
  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. ↑ Otero, Sebastian Alberto (June 28, 2011), "g Herculis", AAVSO Website, American Association of Variable Star Observers , retrieved 20 July 2014
  14. ↑ Posch, Th.; et al. (October 2002), "On the origin of the 19.5 μ m feature. Identifying circumstellar Mg-Fe-oxides", Astronomy and Astrophysics, 393: L7 –L10, Bibcode:2002A&A...393L...7P, doi: 10.1051/0004-6361:20021127 .
  15. ↑ Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (January 2022), "Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs", Astronomy and Astrophysics, 657: A7, arXiv: 2109.10912 , Bibcode:2022A&A...657A...7K, doi: 10.1051/0004-6361/202142146 , ISSN   0004-6361
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