Omega2 Scorpii

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ω2 Scorpii
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) +4.320[2]
Characteristics
Evolutionary stage horizontal branch[3]
Spectral type G6/8III[4]
U−B Template:Engvar +0.494[2]
B−V Template:Engvar +0.850[2]
Astrometry
Radial velocity (Rv)−5.4[5] km/s
Proper motion (μ) RA: +44.81[1] mas/yr
Dec.: −45.42[1] mas/yr
Parallax (π)11.22±0.32 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−0.62[6]
Details
Mass3.27[6] Template:Solar mass
Radius15.0[7] Template:Solar radius
Luminosity163[7] Template:Solar luminosity
Surface gravity (log g)Template:Val[8] cgs
TemperatureTemplate:Val[8] K
Metallicity [Fe/H]Template:Val[8] dex
Age282[6] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Jabhat al Akrab,[9] ω2 Sco, 10 Scorpii, BD−20°4408, HD 144608, HIP 78990, HR 5997, SAO 184135[10]
Database references
SIMBADdata

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ω2 Scorpii, Latinised as Omega2 Scorpii, is a suspected[11] variable star in the zodiac constellation of Scorpius. A component of the visual double star ω Scorpii, it is bright enough to be seen with the naked eye having an apparent visual magnitude of +4.320.[2] The distance to this star, as determined using parallax measurements,[1] is around 291 light years. The visual magnitude of this star is reduced by 0.38 because of extinction from interstellar dust.[6]

It is 0.05 degree north of the ecliptic, so can be occulted by the moon and planets.

This is a G-type giant star with a stellar classification of G6/8III.[4] With an estimated age of 282 million years,[6] it is an evolved, thin disk star that is currently on the red horizontal branch.[3] The interferometry-measured angular diameter of this star is 1.63 ± 0.10 mas,[12] which, at its estimated distance, equates to a physical radius of nearly 16 times the radius of the Sun.[13] It has 3.27 times the mass of the Sun,[6] and radiates 141 times the Sun's luminosity[14] The effective temperature of the star's outer atmosphere is 5,363 K.[8]

Names

In the Cook Islands, a traditional story is told of twins who flee their parents into the sky and become the pair of stars Omega2 and Omega1 Scorpii. The girl, who is called Piri-ere-ua "Inseparable", keeps tight hold of her brother, who is not named.[15] (The IAU used a version of this story from Tahiti to name Mu2 Scorpii.)

References

Template:Reflist

External links

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Template:Stars of Scorpius

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  15. Johannes Carl Andersen (1931) Myths and Legends of the Polynesians. 1995 Dover reprint, p.399–400.