Delta Velorum

δ Velorum
Location of δ Velorum (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Vela
δ Vel A
Right ascension 08h 44m 42.226s[1]
Declination −54° 42′ 31.76″[1]
Apparent magnitude (V) 1.95 - 2.43[2]
δ Vel B
Right ascension 08h 44m 42.203s[1]
Declination −54° 42′ 30.60″
Apparent magnitude (V) 5.54[3]
Characteristics
U−B color index +0.07[4]
B−V color index +0.04[4]
δ Vel A
Spectral type A1 Va(n)[5]
Variable type Algol[6]
δ Vel B
Spectral type F7.5V[7]
Astrometry
Radial velocity (Rv)+2.2[8] km/s
Proper motion (μ) RA: +28.99[9] mas/yr
Dec.: −103.35[9] mas/yr
Parallax (π)40.49 ± 0.39 mas[9]
Distance80.6 ± 0.8 ly
(24.7 ± 0.2 pc)
Absolute magnitude (MV)0.02/3.60[10]
Orbit[7]
Primaryδ Vel A
Companionδ Vel B
Period (P)143.2 yr
Semi-major axis (a)1.996″
Eccentricity (e)0.475
Inclination (i)105.1°
Orbit[7]
Primaryδ Vel Aa
Companionδ Vel Ab
Period (P)45.1503 days
Semi-major axis (a)0.01651″
Eccentricity (e)0.287
Inclination (i)89.04°
Details
δ Vel Aa
Mass2.43[7] M☉
Radius2.79–2.97[7] R☉
Luminosity67[7] L☉
Surface gravity (log g)3.78–3.90[7] cgs
Temperature9,440[7] K
Metallicity [Fe/H]−0.33[7] dex
Rotation1.05[7] days
Rotational velocity (v sin i)143.5[7] km/s
δ Vel Ab
Mass2.27[7] M☉
Radius2.37–2.52[7] R☉
Luminosity51[7] L☉
Surface gravity (log g)3.99–4.10[7] cgs
Temperature9,830[7] K
Metallicity [Fe/H]−0.33[7] dex
Rotational velocity (v sin i)149.6[7] km/s
Age400 million[10] years
δ Vel B
Mass1.35–1.46[7] M☉
Radius1.43[7] R☉
Luminosity3.5[7] L☉
Temperature6,600[7] K
Other designations
Alsephina, CD−54°1788, GCTP 2098.00, HD 74956, HIP 42913, HR 3485, SAO 236232, WDS 08447-5443
Database references
SIMBADdata

Delta Velorum (δ Velorum, abbreviated Delta Vel, δ Vel) is a triple star system in the southern constellation of Vela, near the border with Carina, and is part of the False Cross. Based on parallax measurements, it is approximately 80.6 light-years (24.7 parsecs) from the Sun. It is one of the stars that at times lies near the south celestial pole due to precession.

δ Velorum consists of an eclipsing binary, designated Delta Velorum A, and a more distant third companion, Delta Velorum B. δ Velorum A's two components are themselves designated Aa (officially named Alsephina /ælsɪˈfaɪnə/, the traditional name for the entire system) and Ab.

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