Xi Scorpii

Xi Scorpii (ξ Sco) is part of a quintuple star system in the constellation Scorpius. It was assigned this designation by Bayer, although Ptolemy had catalogued the star in Libra. Flamsteed assigned it the designation 51 Librae, but this has fallen out of use since modern constellation boundaries assign the star to Scorpius.[15]

Xi Scorpii
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
ξ Sco ABC
Right ascension 16h 04m 22.191s[1]
Declination −11° 22′ 22.60″[1]
Apparent magnitude (V) 4.17[2]
(5.16 / 4.87 / 7.30)[3]
Component D
Right ascension 16h 04m 25.9260s[4]
Declination −11° 26′ 57.778″[4]
Apparent magnitude (V) 7.43[5]
Component E
Right ascension 16h 04m 26.7188s[6]
Declination −11° 26′ 59.553″[6]
Apparent magnitude (V) 7.81[7]
Characteristics
ξ Sco ABC
Spectral type F4(V) + F6(V) + G1V[8]
U−B color index +0.00[9]
B−V color index +0.45[9]
Components DE
Spectral type K1(V) + K1(V)[10]
U−B color index +0.315[9]
B−V color index +0.75[9]
Astrometry
ξ Sco ABC
Radial velocity (Rv)−36.33±0.83[11] km/s
Proper motion (μ) RA: −63.2[1] mas/yr
Dec.: −27.0[1] mas/yr
Component E
Radial velocity (Rv)−31.96±0.13[4] km/s
Proper motion (μ) RA: −61.607[4] mas/yr
Dec.: −22.227[4] mas/yr
Parallax (π)35.8898 ± 0.0200 mas[4]
Distance90.88 ± 0.05 ly
(27.86 ± 0.02 pc)
Absolute magnitude (MV)4.47[12]
Component E
Radial velocity (Rv)−32.28±0.12[6] km/s
Proper motion (μ) RA: −56.334[6] mas/yr
Dec.: −20.357[6] mas/yr
Parallax (π)35.8718 ± 0.0237 mas[6]
Distance90.92 ± 0.06 ly
(27.88 ± 0.02 pc)
Absolute magnitude (MV)5.18[12]
Orbit[3]
Primaryξ Sco A
Companionξ Sco B
Period (P)45.90±0.60 yr
Semi-major axis (a)0.654±0.006″
Eccentricity (e)0.744±0.001
Inclination (i)34.5±1.0°
Longitude of the node (Ω)25.3±4.0°
Periastron epoch (T)B 1997.22±0.02
Argument of periastron (ω)
(secondary)		163.8±5.0°
Orbit[3]
Primaryξ Sco AB
Companionξ Sco C
Period (P)1514.43 yr
Semi-major axis (a)7.755″
Eccentricity (e)0.041
Inclination (i)131.5°
Longitude of the node (Ω)47.4°
Periastron epoch (T)B 2226.10
Argument of periastron (ω)
(secondary)		59.3°
Details
D
Mass0.89[4] M☉
Radius0.94[4] R☉
Luminosity0.71[4] L☉
Surface gravity (log g)4.49[13] cgs
Temperature5,529[13] K
Age2.3[14] Gyr
E
Mass0.88[6] M☉
Radius0.77[6] R☉
Luminosity0.44[6] L☉
Surface gravity (log g)4.54[13] cgs
Temperature5,217[13] K
Age2.3[14] Gyr
Other designations
Components ABC: ξ Sco, BD−10°4237, GJ 9540, HIP 78727, SAO 159665 (only AB), ADS 9909
ξ Sco A: HD 144070, HR 5978
ξ Sco B: HD 144069, HR 5977
ξ Sco C: SAO 159666
Other designations
Components DE: GJ 9541, ADS 9910
Component D: BD−11°4057, HD 144087, HIP 78738, SAO 159668
Component E: BD−11°4058, HD 144088, HIP 78739, SAO 159670
Database references
SIMBADξ Sco ABC
ξ Sco AB
ξ Sco A
ξ Sco B
ξ Sco C
Component D
Component E
ARICNSξ Sco A
ξ Sco B
ξ Sco C

Nomenclature

ξ Scorpii (Latinized to Xi Scorpii) is the star's Bayer designation. Xi Scorpii has no proper name, though it was erroneously known as Graffias before that name was applied to Beta Scorpii.[16] Its Flamsteed designation is 51 Librae.[15] When the modern constellation boundaries were drawn, Xi Scorpii was assigned to Scorpius, and the Flamsteed designation fell out of use.

The five stars of the Xi Scorpii system all have different designations, plus some designations that apply to more than one star. Xi Scorpii A, B, and C appear very close together in the sky and are typically grouped under a single multiple star designation, while components D and E are usually grouped under a separate multiple star designation designation. For example, Struve's catalogue of multiple stars includes the pair AB and C as Σ1998[17] and the pair D and E as Σ1999.[18]

ComponentBayerHRHDSAOHIPGJ
Aξ Scorpii5978144070159665787279540
B5977144069
Cnonenone159666
Dnonenone144087159668787389541
Enonenone14408815967078739

Properties

The Xi Scorpii system consists of five stars in two groups separated by about 4.7 arcminutes (or 0.08°) on the sky.[19]

The brighter group contains Xi Scorpii A, B, and C. A and B are both yellow-white F-type stars. A is slightly brighter and warmer.[8] They are separated by 0.744 arcseconds on average, and orbit around a common center once every 45.9 years.[3] The dimmer, seventh-magnitude Xi Scorpii C orbits this pair at about ten times the distance, having a separation of around 7.6 arcseconds.[3]

The second group contains components D and E, both K-type main-sequence stars, separated by about 11.9 arcseconds. They are known to be associated to each other and with the rest of the stars, because all stars share similar proper motions.[19]

References
  1. Roeser, S.; Bastian, U. (1988). "A new star catalogue of SAO type". Astronomy and Astrophysics Supplement Series. 74: 449–451. Bibcode:1988A&AS...74..449R.
  2. "* ksi Sco". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2 August 2017.
  3. "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 1 August 2017. Retrieved 2 July 2017.
  4. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  5. "HD 144087". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2 August 2017.
  6. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  7. "HD 144088". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2 August 2017.
  8. Skiff, B. A. (2014). "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications". VizieR On-line Data Catalog. 1. Bibcode:2014yCat....1.2023S.
  9. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  10. Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5: 0. Bibcode:1999MSS...C05....0H.
  11. Tokovinin, A. A.; Smekhov, M. G. (2002). "Statistics of spectroscopic sub-systems in visual multiple stars". Astronomy & Astrophysics. 382: 118–123. Bibcode:2002A&A...382..118T. doi:10.1051/0004-6361:20011586.
  12. Boro Saikia, S.; et al. (2018). "Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles". Astronomy and Astrophysics. 616: A108. arXiv:1803.11123. Bibcode:2018A&A...616A.108B. doi:10.1051/0004-6361/201629518. S2CID 118915212.
  13. Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881.
  14. Stanford-Moore, S. Adam; Nielsen, Eric L.; De Rosa, Robert J.; MacIntosh, Bruce; Czekala, Ian (2020). "BAFFLES: Bayesian Ages for Field Lower-mass Stars". The Astrophysical Journal. 898 (1): 27. arXiv:2006.04811. Bibcode:2020ApJ...898...27S. doi:10.3847/1538-4357/ab9a35.
  15. Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy. 18 (3): 209. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305. S2CID 118445625.
  16. Allen, R. H. (1899). Star-names and Their Meanings. New York: G. E. Stechert. p. 371.
  17. "** STF 1998". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 14 October 2017.
  18. "** STF 1999AB". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 14 October 2017.
  19. Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
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