Delta Delphini

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.

Delta Delphini

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]
Characteristics
Spectral type kA7hF0mF0(IV-V)[4]
B−V color index +0.302[2]
Variable type δ Sct[3]
Astrometry
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]
Orbit[5]
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)
(secondary)		65.07±0.32°
Semi-amplitude (K1)
(primary)		13.88±0.14 km/s
Semi-amplitude (K2)
(secondary)		15.27±0.07 km/s
Details
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
SIMBADdata

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]

References
  1. 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. 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. 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. 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. 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. 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. 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.
  • Kaler, James B. (August 3, 2007), "Delta Delphini", Stars, University of Illinois, retrieved 2017-06-28.
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