Xi Scorpii

ξ Scorpii
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Scorpius
Right ascension 16h 04m 22.1s
Declination −11° 22' 23"
Apparent magnitude (V) combined: +4.16
ABC: 4.8 + 5.1 + 7.6
DEF: 7.4 + 8.1 + 11
Distance92.5 ± 6.7 ly
(28.4 ± 2.1 pc)
Spectral typeABC: F5IV + F8V + ?
DEF: K0 + K0 + ?
Other designations
Graffias,[1] ξ Sco, 51 Lib, HR 5977 + HR 5978, HD 144069 + HD 144070 + HD 144087 + HD 144088, SAO 159665, HIP 78727 + HIP 78738 + HIP 78739, ADS 9909 + ADS 9910, CCDM J16044-1123

Xi Scorpii (ξ Sco, ξ Scorpii) is a star system in the constellation Scorpius. It was also 51 Lib.

The Xi Scorpii system consists of at least five stars in two groups separated by 4.67 arcminutes (or 0.08°) on the sky, corresponding to a distance of at least 8000 astronomical units (AU).

The brighter group contains Xi Scorpii A, B, and C. A and B are both yellow-white F-type stars. A is a slightly brighter and warmer magnitude +4.8 subgiant, while B is a magnitude +5.1 main sequence dwarf. They are separated by 0.76 arcseconds, or at least 21 AU, roughly a Sun–Uranus distance, and orbit around a common centre once every 46 years. The magnitude +7.6 Xi Scorpii C orbits this pair at ten times the distance, having a separation of 7.6 arcseconds.

The second group contains Xi Scorpii D and E. Both D and E are K-type stars, which are separated by 11.5 arcseconds, more than 320 AU.

Xi Scorpii also possesses a sixth component, the 11th magnitude Xi Scorpii F, located 81 arcseconds from D. It is not known to be gravitationally bound to the other five components.

Xi Scorpii was a latter designation of 51 Librae.[2]

References

  1. ↑ Allen, R. H., (1899) Star-names and Their Meanings, New York: G. E. Stechert, p. 371.
  2. ↑ Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy, Vol.18, NO. 3/AUG, P.209, 1987. 18: 218. Bibcode:1987JHA....18..209W.

Coordinates: 16h 04m 22.1s, −11° 22′ 23″


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