- Mu Sagittarii
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μ Sagittarii Observation data
Epoch J2000.0 Equinox J2000.0Constellation Sagittarius Right ascension 18h 13m 45.8s Declination −21° 03′ 32″ Apparent magnitude (V) +3.84 Distance > 3912 ly
(> 920 pc)Spectral type B2III Other designations Mu Sagittarii (μ Sgr, μ Sagittarii) is a star system in the constellation Sagittarius. It also has the traditional name Polis, from a Coptic word meaning foal[1]. In ancient Chinese astronomy, it is the 1st of 6 stars in the Dipper or 'South Dipper' mansion of the Black Tortoise of the North.
The stars in the Polis system are designated Polis A through Polis E. Polis is more than 3000 light years from Earth.
The primary component in this system, Polis A, is a type B giant star with a total luminosity of 180,000 times that of the Sun and a radius of 115 times solar. Its mass is 23 times the solar mass while it has a surface temperature of 11,100 kelvins.
Polis A is an eclipsing binary, bringing the total of stars in the system to six. The primary component is a spectral type B8 supergiant and the companion is a type B2 giant. The orbital period of the binary is 180.55 days. Due to occultation of the primary by the companion, the apparent magnitude of Polis A varies between +3.84 and +3.96.
The remaining components are very weakly bound to the Polis system.
Component Apparent
MagnitudeSeparation
from Polis AMinimum distance
from Polis APolis A +3.84 - - Polis B +11.5 16.9 arcseconds 42 200 AU or 0.67 ly Polis C +13.5 25.8 arcseconds 64 500 AU or 1.02 ly Polis D +9.9 48.5 arcseconds 121 200 AU or 1.92 ly Polis E +9.4 50.0 arcseconds 125 000 AU or 1.98 ly References
External links
Bayer α (Rukbat) • β¹ (Arkab Prior) • β² (Arkab Posterior) • γ¹ • γ² (Alnasl) • δ (Kaus Media) • ε (Kaus Australis) • ζ (Ascella) • η • θ¹ • θ² • ι • κ¹ • κ² • λ (Kaus Borealis) • μ (Polis) • ν¹ (Ain al Rami) • ν² • ξ¹ • ξ² • ο • π (Albaldah) • ρ¹ • ρ² • σ (Nunki) • τ • υ • φ (Nanto) • χ¹ • χ² • χ³ • ψ • ω • b¹ • c • d • e¹ • e² • f • g • h¹ • h² • AFlamsteed 3 • 4 • 6 • 7 • 9 • 10 (γ², Alnasl) • 11 • 13 (μ, Polis) • 14 • 15 • 16 • 17 • 18 • 19 (δ, Kaus Media) • 20 (ε, Kaus Australis) • 21 • 22 (λ, Kaus Borealis) • 24 • 25 • 26 • 27 (φ, Nanto) • 28 • 29 • 30 • 32 (ν¹, Ain al Rami) • 33 • 34 (σ, Nunki) • 35 (ν²) •36 (ξ¹) • 37 (ξ²) • 38 (ζ, Ascella) • 39 (ο) • 40 (τ) • 41 (π, Albaldah) • 42 (ψ) • 43 (d) • 44 (ρ¹) • 45 (ρ²) • 46 (υ) • 47 (χ¹) • 48 (χ²) • 49 (χ³) • 50 • 51 (h¹) • 52 (h²) • 53 • 54 (e¹) • 55 (e²) • 56 (f) • 57 • 58 (ω) • 59 (b¹) • 60 (A) • 61 (g) • 62 (c) • 63 • 65 • 63 OphNearby Ross 154 • Gliese 783 • Gliese 745Other Categories:- Algol variables
- Bayer objects
- B-type giants
- B-type supergiants
- Flamsteed objects
- Henry Draper Catalogue objects
- HIP objects
- Multiple star systems
- Sagittarius constellation
- Eclipsing binaries
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