g Herculis is a binary star[12] system in the northern constellation of Hercules. 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]
| 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 | |
| Database references | |
| SIMBAD | data |
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]
References
edit- ^ "Light Curve", Hipparcos ESA, ESA, retrieved 20 September 2022.
- ^ a b c d e 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.
- ^ a b c 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.
- ^ a b c d e 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
- ^ a b 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.
- ^ a b c 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.
- ^ 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.
- ^ 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.
- ^ a b c 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.
- ^ a b 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.
- ^ "g Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-13.
- ^ 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.
- ^ Otero, Sebastian Alberto (June 28, 2011), "g Herculis", AAVSO Website, American Association of Variable Star Observers, retrieved 20 July 2014
- ^ 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.