Delta Delphini

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Delta Delphini
Diagram showing star positions and boundaries of the Delphinus constellation and its surroundings. Delta Delphinus is circled.
Diagram showing star positions and boundaries of the Delphinus constellation and its surroundings. Delta Delphinus is circled.
A star chart of the Delphinus constellation showing the position of δ Delphinus (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Delphinus
Right ascension  20h 43m 27.53338s[1]
Declination +15° 04′ 28.4773″[1]
Apparent magnitude (V) 4.43[2] (4.38 - 4.49)[3]
Spectral type kA7hF0mF0(IV-V)[4]
B−V color index +0.302[2]
Variable type δ Sct[3]
Radial velocity (Rv)9.48±0.07[5] km/s
Proper motion (μ) RA: −20.44[1] mas/yr
Dec.: −43.33[1] mas/yr
Parallax (π)14.61 ± 0.20[1] mas
Distance223 ± 3 ly
(68.4 ± 0.9 pc)
Absolute magnitude (MV)+0.25[6]
PrimaryDelta Delphini A
CompanionDelta Delphini B
Period (P)40.60505±0.00014 d
Semi-major axis (a)5.4676±0.0037
Eccentricity (e)0.64008±0.00018
Inclination (i)13.92±0.18°
Longitude of the node (Ω)63.73±0.33°
Periastron epoch (T)56823.5019±0.0028 MJD
Argument of periastron (ω)
Semi-amplitude (K1)
13.88±0.14 km/s
Semi-amplitude (K2)
15.27±0.07 km/s
δ Del A
Mass1.52[7] M
Radius3.9[8] R
Luminosity59.9[9] L
Surface gravity (log g)3.71[7] cgs
Temperature7,226±246[7] K
Metallicity [Fe/H]−0.07±0.05[10] dex
Rotational velocity (v sin i)29.4[2] km/s
Age945[7] Myr
Other designations
δ Del, 11 Del, BD−14° 4403, HD 197461, HIP 102281, HR 7928, SAO 106425[11]
Database references

Delta Delphini, Latinized from δ Delphini, is a binary star[12] in the northern constellation of Delphinus. It is visible to the naked eye with an apparent visual magnitude of 4.43.[2] Based upon an annual parallax shift of 14.61 mas as seen from the Earth,[1] the system is located about 223 light years from the Sun.

This is a double-lined spectroscopic binary[12] system with an orbital period of 40.58 days.[12] The two components are nearly identical chemically peculiar stars, having a combined stellar classification of kA7hF0mF0(IV-V).[4] This notation indicates the calcium K line matches an A7 star, the hydrogen lines an F0 star, and the metal lines an F0 star. Each of the stars is a Delta Scuti variable, with the system having a dominant period of 0.1568 days and an amplitude of 0.0700 in magnitude.[2] Delta Delphini forms the prototype of a class of metal-lined δ Scuti subgiant or giant stars.[13]


  1. ^ 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.
  2. ^ a b c d e Chang, S.-W.; et al. (2013), "Statistical Properties of Galactic δ Scuti Stars: Revisited", The Astronomical Journal, 145 (5): 132, arXiv:1303.1031, Bibcode:2013AJ....145..132C, doi:10.1088/0004-6256/145/5/132.
  3. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  4. ^ a b Gray, R. O.; Garrison, R. F. (1989), "The early F-type stars - Refined classification, confrontation with Stromgren photometry, and the effects of rotation", Astrophysical Journal Supplement Series, 69: 301, Bibcode:1989ApJS...69..301G, doi:10.1086/191315.
  5. ^ a b Gardner, Tyler; et al. (2018). "Precision Orbit of δ Delphini and Prospects for Astrometric Detection of Exoplanets". The Astrophysical Journal. 855 (1). 1. arXiv:1802.00468. Bibcode:2018ApJ...855....1G. doi:10.3847/1538-4357/aaac80.
  6. ^ 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.
  7. ^ a b c d 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.
  8. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  9. ^ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  10. ^ Prugniel, Ph.; Vauglin, I.; Koleva, M. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769.
  11. ^ "del Del". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-28.
  12. ^ a b c Liakos, Alexios; Niarchos, Panagiotis (February 2017), "Catalogue and properties of δ Scuti stars in binaries", Monthly Notices of the Royal Astronomical Society, 465 (1): 1181–1200, arXiv:1611.00200, Bibcode:2017MNRAS.465.1181L, doi:10.1093/mnras/stw2756
  13. ^ Baade, D.; Bardelli, S.; Beaulieu, J. Ph.; Vogel, S. (March 1993), "A spectroscopic search for nonradial pulsations in the Delta Scuti stars Delta Delphini and Epsilon Cephei", Astronomy and Astrophysics, 269 (1–2): 195–200, Bibcode:1993A&A...269..195B.

External links[edit]

  • Kaler, James B. (August 3, 2007), "Delta Delphini", Stars, University of Illinois, retrieved 2017-06-28.