111 Herculis
111 Herculis is a suspected astrometric binary[8] star system located 92 light years from the Sun in the northern constellation Hercules. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.34.[2] The system is moving nearer to the Earth with a heliocentric radial velocity of −45 km/s, and may come as close as 37 light-years in 537,000 years.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 18h 47m 01.23246s[1] |
| Declination | +21° 46′ 53.4381″[1] |
| Apparent magnitude (V) | 4.34[2] |
| Characteristics | |
| Spectral type | A5III[3] |
| B−V color index | 0.148±0.003[2] |
| Astrometry | |
| Radial velocity (Rv) | −44.6±2.7[2] km/s |
| Proper motion (μ) | RA: +100.536[1] mas/yr Dec.: +116.333[1] mas/yr |
| Parallax (π) | 35.3525 ± 0.2680 mas[1] |
| Distance | 92.3 ± 0.7 ly (28.3 ± 0.2 pc) |
| Absolute magnitude (MV) | 2.04[2] |
| Details | |
| Mass | 2.40[4] M☉ |
| Radius | 1.6[5] R☉ |
| Luminosity | 12.84[2] L☉ |
| Surface gravity (log g) | 4.35[4] cgs |
| Temperature | 8,873±302[4] K |
| Metallicity [Fe/H] | 0.33[6] dex |
| Rotational velocity (v sin i) | 71[4] km/s |
| Age | 559[4] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
According to Cowley et al. (1969), the visible component has a stellar classification of A5III,[3] matching an A-type giant star. Abt and Morrell (1995) listed it as type A3IV, suggesting it is instead a less evolved subgiant star.[9] The interferometry-measured angular diameter of the primary component is 0.52±0.02 mas,[10] which, at its estimated distance, equates to a physical radius of roughly 1.6 times the radius of the Sun.[5] The star is estimated to be 559[4] million years old with 2.40[4] times the mass of the Sun and is spinning with a projected rotational velocity of 71 km/s.[4] It is radiating 13 times the Sun's luminosity from its photosphere at an effective temperature of 8,873 K.[4]
References
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d e f g 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.
- ^ a b Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819
- ^ a b c d e f g h i David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
- ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
- ^ Erspamer, D.; North, P. (February 2003), "Automated spectroscopic abundances of A and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE", Astronomy and Astrophysics, 398 (3): 1121–1135, arXiv:astro-ph/0210065, Bibcode:2003A&A...398.1121E, doi:10.1051/0004-6361:20021711, S2CID 1109164.
- ^ "111 Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-18.
- ^ 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.
- ^ Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
- ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039