 | |
| 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 | |
| Spectral type | A3 IVs [3] |
| U−B color index | +0.05 [2] |
| B−V color index | +0.08 [2] |
| Astrometry | |
| Radial velocity (Rv) | −25.00±4.2 [4] 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 [5] |
| Details | |
| Mass | 2.12 [6] M☉ |
| Radius | 2.2 [7] R☉ |
| Luminosity | 35 [8] L☉ |
| Surface gravity (log g) | 4.38 [6] cgs |
| Temperature | 9,355±318 [6] K |
| Metallicity [Fe/H] | +0.56 [5] dex |
| Rotational velocity (v sin i) | 65 [8] km/s |
| Age | 309 [6] Myr |
| Other designations | |
| 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. [4]
The stellar classification of the visible component is A3 IVs, [3] 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. [8] 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 [6] and radius [7] of the Sun, and is radiating 35 [8] times the Sun's luminosity from its photosphere at an effective temperature of around 9,355 K. [6]
References
- ^ a b c d e f 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 Feinstein, A. (1974), "Photoelectric UBVRI observations of AM stars", Astronomical Journal, 79: 1290, Bibcode: 1974AJ.....79.1290F, doi: 10.1086/111675.
- ^ 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 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.
- ^ a b 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 c d e f 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 Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics, 367 (Third ed.): 521–524, arXiv: astro-ph/0012289, Bibcode: 2001A&A...367..521P, doi: 10.1051/0004-6361:20000451, S2CID 425754.
- ^ a b c d 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.
- ^
a
b
"eta Del".
SIMBAD.
Centre de données astronomiques de Strasbourg. Retrieved 2017-08-18.
{{ cite web}}: CS1 maint: postscript ( link) - ^ 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.
