Delta Delphini

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]
Characteristics
Spectral type kA7hF1VmF1pSrEuCr:[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 mas[1]
Distance223 ± 3 ly
(68.4 ± 0.9 pc)
Absolute magnitude (MV)+0.25[6]
Orbit[5]
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
Mass1.78[5] M☉
Radius3.43[5] R☉
Luminosity32.4[5] L☉
Surface gravity (log g)3.71[7] cgs
Temperature7,440±210[5] K
Metallicity [Fe/H]−0.5[5] dex
Rotational velocity (v sin i)17[5] km/s
Age945[7] Myr
δ Del B
Mass1.62[5] M☉
Radius3.48[5] R☉
Luminosity28.8[5] L☉
Temperature7,110±180[5] K
Rotational velocity (v sin i)12[5] km/s
Other designations
δ Del, 11 Del, BD+14°4403, HD 197461, HIP 102281, HR 7928, SAO 106425[8]
Database references
SIMBADdata

Delta Delphini, Latinized from δ Delphini, is a binary star[9] 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.

A light curve for Delta Delphini, plotted from Hipparcos data[10]

This is a double-lined spectroscopic binary[9] system with an orbital period of 40.58 days.[9] The two components are nearly identical chemically peculiar stars, having a combined stellar classification of kA7hF1VmF1pSrEuCr:. This notation indicates the calcium K line matches an A7 star, the hydrogen lines an F1 star, and the metal lines an F1 star, with particularly strong lines of strontium, europium, and chromium. 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.[11]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Chang2013 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference gray2001 was invoked but never defined (see the help page).
  5. ^ a b c d e f g h i j k l m Cite error: The named reference Gardner2018 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference David2015 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Liakos2017 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference HIPCurve was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Baade1993 was invoked but never defined (see the help page).