Epsilon Scorpii

ε Scorpii
Location of ε Sco (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 16h 50m 09.8s[1]
Declination –34° 17′ 36″[1]
Apparent magnitude (V) +2.310[2] (2.24 - 2.35)[3])
Characteristics
Spectral type K1 III[4]
U−B color index +1.147[2]
B−V color index +1.150[2]
Variable type suspected[3]
Astrometry
Radial velocity (Rv)–2.5[5] km/s
Proper motion (μ) RA: –614.85[1] mas/yr
Dec.: –255.98[1] mas/yr
Parallax (π)51.19 ± 0.22 mas[1]
Distance63.7 ± 0.3 ly
(19.54 ± 0.08 pc)
Absolute magnitude (MV)0.78 ± 0.04[6]
Details
Mass1.31[7] M☉
Radius12.6[8] R☉
Luminosity60[7] L☉
Surface gravity (log g)2.34[7] cgs
Temperature4,560[9] K
Metallicity [Fe/H]–0.17[9] dex
Rotational velocity (v sin i)2.6 ± 0.5[10] km/s
Age3.92[7] Gyr
Other designations
Wei, Larawag, 26 Scorpii, CD–34 11285, FK5 628, GCTP 3823.00, Gl 639.1, HD 151680, HIP 82396, HR 6241, LHS 3244, SAO 208078.[11]
Database references
SIMBADdata

Epsilon Scorpii (ε Scorpii, abbreviated Eps Sco, ε Sco), formally named Larawag /ˈlærəwæɡ/,[12] is a star in the southern zodiac constellation of Scorpius. It has an apparent visual magnitude of +2.3,[2] making it the fifth-brightest member of the constellation. Parallax measurements made during the Hipparcos mission provide an estimated distance to this star of around 63.7 light-years (19.5 parsecs) from the Sun.[1]

Epsilon Scorpii has a stellar classification of K1 III,[4] which indicates it has exhausted the supply of hydrogen at its core and evolved into a giant star. The interferometry-measured angular diameter of this star, after correcting for limb darkening, is 5.99 ± 0.06 mas,[13] which, at its estimated distance, equates to a physical radius of nearly 13 times the radius of the Sun.[8] Presently it is generating energy through the nuclear fusion of helium at its core, which, considering the star's composition, places it along an evolutionary branch termed the red clump.[14] The star's outer atmosphere has an effective temperature of 4,560 K,[9] giving it the orange hue of a cool K-type star.

ε Scorpii is classified as a suspected variable star,[3] although a study of Hipparcos photometry showed a variation of no more than 0.01–0.02 magnitudes.[14] It is an X-ray source with a luminosity of (1.5–1.6) × 1027 erg s−1.[6][15]

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  12. ^ "Naming Stars". IAU.org. Retrieved 16 December 2017.
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  14. ^ a b Cite error: The named reference ba10_593 was invoked but never defined (see the help page).
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