Eta Delphini
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 33m 57.04099s[1] |
| Declination | +13° 01′ 38.1437″[1] |
| Apparent magnitude (V) | 5.38[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | A3 IVs[4] |
| U−B color index | +0.05[2] |
| B−V color index | +0.08[2] |
| Astrometry | |
| Radial velocity (Rv) | −25.00±4.2[5] km/s |
| Proper motion (μ) | RA: +73.15[1] mas/yr Dec.: +24.66[1] mas/yr |
| Parallax (π) | 13.81±1.17 mas[1] |
| Distance | 240 ± 20 ly (72 ± 6 pc) |
| Absolute magnitude (MV) | +1.11[6] |
| Details | |
| Mass | 2.12[7] M☉ |
| Radius | 1.43[8] R☉ |
| Luminosity | 11.5[8] L☉ |
| Surface gravity (log g) | 4.38[7] cgs |
| Temperature | 9,355±318[7] K |
| Metallicity [Fe/H] | +0.56[6] dex |
| Rotational velocity (v sin i) | 65[3] km/s |
| Age | 309[7] Myr |
| Other designations | |
| η Del, 3 Del, BD+12°4378, GC 28617, HD 195943, HIP 101483, HR 7858, SAO 106248[9] | |
| Database references | |
| SIMBAD | data |
Eta Delphini, Latinized from η Delphini, is a candidate astrometric binary[10] star system in the northern constellation of Delphinus. It has an apparent magnitude of about 5.4, meaning that it is faintly visible to the naked eye. Based upon a parallax measurement of 13.81[1] mas made by the Hipparcos spacecraft, this star is around 240 light years away from the Sun. It is advancing in general direction of the Earth with a radial velocity of −25 km/s.[5]
The stellar classification of the visible component is A3 IVs,[4] which matches an A-type subgiant star with narrow absorption lines.[11] It is a suspected chemically peculiar star[12] that is about 64.3%±9.2% of the way through its main sequence lifetime.[3] SIMBAD lists this star as a variable star,[9] although it is not catalogued as such in the GCVS.[13] It has more than double the mass[7] and radius of the Sun,[8] and is radiating 11.5 times the Sun's luminosity[8] from its photosphere at an effective temperature of around 9,355 K.[7]
References
[edit]- 1 2 3 4 5 6 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.
- 1 2 3 Feinstein, A. (1974), "Photoelectric UBVRI observations of AM stars", Astronomical Journal, 79: 1290, Bibcode:1974AJ.....79.1290F, doi:10.1086/111675.
- 1 2 3 Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
- 1 2 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.
- 1 2 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
- 1 2 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.
- 1 2 3 4 5 6 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.
- 1 2 3 4 Stassun, Keivan G.; et al. (2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467.
- 1 2 "eta Del", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-08-18.
- ↑ 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.
- ↑ Allen, J. S., "The Classification of Stellar Spectra", Department of Physics and Astronomy: Astrophysics Group, University College London, retrieved 1 January 2014.
- ↑ Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.
- ↑ Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
