Alpha Delphini

For the racehorse, see Alpha Delphini (horse).
α Delphini A
Location of α Delphini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Delphinus
Right ascension 20h 39m 38.28720s[1]
Declination +15° 54′ 43.4637″[1]
Apparent magnitude (V) +3.777[2] (3.86 + 6.43[3])
Characteristics
Spectral type B9 IV[4]
U−B color index −0.205[2]
B−V color index −0.061[2]
Astrometry
Radial velocity (Rv)−3.40[5] km/s
Proper motion (μ) RA: 53.82 ± 0.43[1] mas/yr
Dec.: 8.47 ± 0.31[1] mas/yr
Parallax (π)12.85 ± 0.44 mas[1]
Distance254 ± 9 ly
(78 ± 3 pc)
Absolute magnitude (MV)−0.4[6]
Orbit[7]
PrimaryAa (A)
CompanionAb (B)
Period (P)6175.3±3.2 d
Semi-major axis (a)0.15809±0.00013"
(12.7±0.4 AU)
Eccentricity (e)0.4615±0.0016
Inclination (i)161.01±0.30°
Longitude of the node (Ω)120.62±1.19°
Periastron epoch (T)JD57988.7
Argument of periastron (ω)
(secondary)		91.73±1.09°
Orbit
PrimaryAb1 (Ba)
CompanionAb2 (Bb)
Period (P)29.9873±0.0021 d
Semi-major axis (a)0.0003587±0.000010"
(0.281±0.008 AU)
Eccentricity (e)0.0761±0.0012
Inclination (i)22.11±0.61°
Longitude of the node (Ω)359.97±0.65°
Periastron epoch (T)JD58762.84
Argument of periastron (ω)
(secondary)		166.43±1.27°
Semi-amplitude (K2)
(secondary)		21.19±0.18 km/s
Details
Aa (A)
Mass3.83±0.33[7] M☉
Radius3.92[8] R☉
Surface gravity (log g)3.93[9] cgs
Temperature11,643[9] K
Rotational velocity (v sin i)144[9] km/s
Age227[9] Myr
Ab1 (Ba)
Mass1.82±0.15[7] M☉
Ab2 (Bb)
Mass1.49±0.12[7] M☉
Other designations
α Del, 9 Delphini, BD+15 4222, HD 196867, HIP 101958, HR 7906, SAO 106357, CCDM J20396+1555, WDS J20396+1555
Database references
SIMBADdata

Alpha Delphini (α Delphini, abbreviated Alpha Del, α Del) is a multiple star system in the constellation of Delphinus.

It consists of a triple star, designated Alpha Delphini A, together with five faint, probably optical companions,[10][11] designated Alpha Delphini B, C, D, E and F. A's two components are themselves designated Alpha Delphini Aa (officially named Sualocin /ˈswɒloʊsɪn/, the historical name for the entire system)[12][13] and Ab.[10]

  1. ^ a b c d e Cite error: The named reference hipparcos was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference oja was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference malkov was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference mk was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference ascc was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference mv was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference gardner2021 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference fitzpatrick was invoked but never defined (see the help page).
  9. ^ a b c d Cite error: The named reference david was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference wds was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference ccdm was invoked but never defined (see the help page).
  12. ^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
  13. ^ "Naming Stars". IAU.org. Retrieved 16 December 2017.