Psi Sagittarii

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Psi Sagittarii
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings
Cercle rouge 100%.svg

Location of ψ Sagittarii (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 19h 15m 32.42658s[1]
Declination −25° 15′ 24.0569″[1]
Apparent magnitude (V) +4.86
Spectral type K2 III + A9 III + A3 V[2]
Proper motion (μ) RA: +45.50[1] mas/yr
Dec.: −31.08[1] mas/yr
Parallax (π) 10.93 ± 0.31[1] mas
Distance 298 ± 8 ly
(91 ± 3 pc)
Absolute magnitude (MV) 0.06[3]
Period (P) 7,319 d
Eccentricity (e) 0.51
Periastron epoch (T) 2442418.795 JD
Argument of periastron (ω)
Semi-amplitude (K1)
10.0 km/s
Semi-amplitude (K2)
13.8 km/s
ψ Sgr A
Mass 2.10[5] M
Luminosity 84[3] L
ψ Sgr Ba/Bb
Mass 1.70/2.70 M
Other designations
ψ Sgr, 42 Sgr, CPD−27° 6737, HD 179950, HIP 94643, HR 7292, SAO 187882, WDS J19155-2515[6]
Database references

Psi Sagittarii (ψ Sagittarii) is a triple star[7] system in the zodiac constellation of Sagittarius. The star system is 298 light years from Earth. The star system has a combined apparent magnitude of +4.86.

The inner pair of this triple star system, components Ba and Bb, have an orbital period of 10.78 days and an eccentricity of 0.47.[7] These in turn share an orbit with the primary, component A, having a period of 20 years and an eccentricity of 0.51.[4]

Name and etymology[edit]

According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, this star was titled as Al Kiladah.[8] This star, together with τ Sgr, ν Sgr, ω Sgr, 60 Sgr and ζ Sgr were Al Udḥiyy, the Ostrich's Nest.[9]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ Docobo, José A.; Andrade, Manuel (November 2006), "A Methodology for the Description of Multiple Stellar Systems with Spectroscopic Subcomponents", The Astrophysical Journal, 652 (1): 681−695, Bibcode:2006ApJ...652..681D, doi:10.1086/508053. 
  3. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, Bibcode:2012AstL...38..331A, arXiv:1108.4971Freely accessible, doi:10.1134/S1063773712050015. 
  4. ^ a b Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727, Bibcode:2004A&A...424..727P, arXiv:astro-ph/0406573Freely accessible, doi:10.1051/0004-6361:20041213. 
  5. ^ Tokovinin, A. (September 2008), "Comparative statistics and origin of triple and quadruple stars", Monthly Notices of the Royal Astronomical Society, 389 (2): 925−938, Bibcode:2008MNRAS.389..925T, arXiv:0806.3263Freely accessible, doi:10.1111/j.1365-2966.2008.13613.x. 
  6. ^ "psi Sgr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-02. 
  7. ^ a b Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x. 
  8. ^ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), California Institute of Technology: Jet Propulsion Laboratory, retrieved 2017-07-02. 
  9. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 355. ISBN 0-486-21079-0. Retrieved 2012-09-04.