Mu Sagittarii

μ Sagittarii
Location of μ Sgr(circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension 18h 13m 45.8s[1]
Declination −21° 03′ 32″[1]
Apparent magnitude (V) +3.85[2]
Characteristics
μ Sgr A
Evolutionary stage Blue supergiant (Aa)
Spectral type B8Iap[3] + B1.5V[4]
U−B color index −0.52[5]
B−V color index +0.22[5]
Variable type EA + α Cyg[6]
μ Sgr B
Spectral type B9III[4]
U−B color index −0.11[5]
B−V color index −0.04[5]
μ Sgr C
U−B color index −0.30[5]
B−V color index +0.23[5]
μ Sgr D
Spectral type B2IV[7]
U−B color index −0.57[5]
B−V color index +0.11[5]
μ Sgr E
Spectral type B2.5V[7]
U−B color index −0.67[5]
B−V color index +0.04[5]
Astrometry
Parallax (π)0.6437 ± 0.038 mas[8]
Distance5,100 ± 300 ly
(1,550 ± 90 pc)
Absolute magnitude (MV)A: −7.1[7]
B: −1.2[9]
D: −3.3[7]
E: −2.1[7]
Details
μ Sgr Aa
Mass14.1 – 30,[10] 23[11] M☉
Radius115[11] R☉
Luminosity180,000[11] L☉
Surface gravity (log g)2.0[10] cgs
Temperature12,000[10] K
μ Sgr Ab
Mass9.8 - 15[10] M☉
Radius12.2[10] R☉
Surface gravity (log g)4.0[10] cgs
Temperature23,000[10] K
Age10[7] Myr
μ Sgr B
Luminosity603[12] L☉
Temperature18,200[12] K
μ Sgr D
Luminosity1,660[12] L☉
Temperature20,400[12] K
μ Sgr E
Mass6.47±0.21[8] M☉
Radius6.36+0.36
−0.31[8] R☉
Luminosity2,668+337
−298[8] L☉
Surface gravity (log g)3.55±0.03[8] cgs
Temperature16,700+200
−300[8] K
Other designations
Polis, μ Sagittarii, μ Sgr, Mu Sgr, 13 Sagittarii, CCDM J18210-2950, IDS 18078-2105, SAO 186497, WDS J18138-2104
μ Sgr A: HD 166937, HIP 89341, HR 6812, PPM 268080, BD−21°4908, FK5 682, GC 24856
μ Sgr D: HD 314059, BD−21°4907
μ Sgr E: HD 314057, BD−21°4909, 2MASS J18134906-2103528
Database references
SIMBADμ Sgr AB
μ Sgr D
μ Sgr E

Mu Sagittarii (μ Sagittarii, abbreviated Mu Sgr, μ Sgr) is a multiple star system in the constellation of Sagittarius. The brightest component, a blue supergiant designated Mu Sagittarii Aa, is formally named Polis /ˈpɒlɪs/.[13] The system is 5,000 light-years from the Sun and is part of the Sgr OB1 stellar association.

  1. ^ a b Cite error: The named reference hipparcos was invoked but never defined (see the help page).
  2. ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ Fraser, M.; Dufton, P. L.; Hunter, I.; Ryans, R. S. I. (2010). "Atmospheric parameters and rotational velocities for a sample of Galactic B-type supergiants". Monthly Notices of the Royal Astronomical Society. 404 (3): 1306. arXiv:1001.3337. Bibcode:2010MNRAS.404.1306F. doi:10.1111/j.1365-2966.2010.16392.x. S2CID 118674151.
  4. ^ a b Cite error: The named reference zasche was invoked but never defined (see the help page).
  5. ^ a b c d e f g h i j Cite error: The named reference echevarria was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
  7. ^ a b c d e f Cite error: The named reference abt1983 was invoked but never defined (see the help page).
  8. ^ a b c d e f Cite error: The named reference dr3e was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference lindroos1985 was invoked but never defined (see the help page).
  10. ^ a b c d e f g Cite error: The named reference polidan was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference kaler was invoked but never defined (see the help page).
  12. ^ a b c d Cite error: The named reference lindroos1986 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference IAU-LSN was invoked but never defined (see the help page).