Epsilon Lupi

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ε Lupi
Location of ε Lupi (circled)
Observation data
J2000.0
Constellation Lupus
Right ascension 15h 22m 40.86826s[1]
Declination –44° 41′ 22.6146″[1]
Apparent magnitude (V) 3.41[2]
Characteristics
Spectral type B2 IV-V[3]
U−B color index –0.778[2]
B−V color index –0.195[2]
Distance
approx. 510 ly
(approx. 160 pc)
Absolute magnitude (MV)−2.55[5]
Semi-amplitude
(K1)
(primary)		53.8 km/s
Semi-amplitude (K2)
(secondary)		64.7 km/s
Details
ε Lup Aa
Rotational velocity (v sin i)
133[3] km/s
ε Lup Ab
Radius3.8[3] R☉
CPD−44° 7342, HD 136504, HIP 75264, HR 5708, SAO 225712 .[6]
Database references
SIMBADdata

Epsilon Lupi,

sufficiently dark skies. It is the fifth-brightest star or star system in the constellation.[2] Parallax measurements give a distance to this system of roughly 510 light-years (160 parsecs).[1]

This system is what astronomers term a double-lined

arcsecond that may be orbiting the pair with a period of about 64 years.[3]

The pair that share the close orbit, Epsilon Lupi Aa and Epsilon Lupi Ab, have estimated masses of 13.24 and 11.46 times the mass of the Sun, respectively. The more distant component, Epsilon Lupi B, has a mass of about 7.64 times the Sun. The combined stellar classification of the system is B2 IV-V, while the individual components may have spectral classes of B3 IV, B3 V, and A5 V, in order of decreasing mass. The inner A-a pair appear to have their rate of spin synchronized with their orbit, so that the same face of each star always faces its partner. The secondary, Epsilon Lupi a, shows regular variation in luminosity of the type that occurs with Beta Cephei variables, at a periodicity of 10.36 cycles per day.[3]

This star system is a probable member of the

moving group of stars that originated together and share a similar trajectory through space.[2]

References

  1. ^
    S2CID 18759600
  2. ^
    doi:10.1086/190168
  3. ^
    S2CID 16644667
  4. Bibcode:1967IAUS...30...57E
    .
  5. S2CID 119257644
    .
  6. Centre de Données astronomiques de Strasbourg
    , retrieved 2012-01-08
  7. ^ The ratio of the periapsis (rp) to the apoapsis (ra) is given by:
    where e is the ellipticity.
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