S Sagittae

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S Sagittae
Sagitta constellation map.svg
Red circle.svg
Location of S Sagittae (circled)
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Sagitta
Right ascension 19h 56m 01.26s [1]
Declination +16° 38′ 05.3″ [1]
Apparent magnitude  (V)5.24 –6.04 [2]
Characteristics
Evolutionary stage Supergiant
Spectral type F6Ib-G5Ib [3]
U−B color index +0.6 –+0.9 [2]
B−V color index +0.7 –+1.0 [2]
Variable type Classical Cepheid [2]
Astrometry
Radial velocity (Rv)−9.91 [4]  km/s
Proper motion (μ)RA: +0.375 [1]   mas/yr
Dec.: −7.100 [1]   mas/yr
Parallax (π)1.6673 ± 0.1106  mas [1]
Distance 2,000 ± 100  ly
(600 ± 40  pc)
Absolute magnitude  (MV)–3.8 [5]
Details
Mass 7 [6]   M☉
Radius 58.5 [7]   R☉
Luminosity 5,200 [8]   L☉
Surface gravity (log g)1.93 [1]   cgs
Temperature 5,400 [5]   K
Metallicity [Fe/H]+0.1 [9]   dex
Age 81 [10]   Myr
Other designations
10  Sge, BD+16° 4067, HD  188727, HIP  98085, HR  7609, SAO  105436
Database references
SIMBAD data

S Sagittae, also known by the Flamsteed designation of 10 Sagittae, a Classical Cepheid variable in the constellation Sagitta that varies from magnitude 5.24 to 6.04 in 8.382 days. [2] Its variable star designation of "S" indicates that it was the second star discovered to be variable in the constellation. Irish amateur astronomer John Ellard Gore was the first to observe its variability in 1885, and Ralph Hamilton Curtiss discovered its changing radial velocity in 1903–04. [11] Harlow Shapley observed in 1916 that the spectrum of it and other Cepheids varied with its brightness, recording it as spectral type F0 leading to maximum, F4 at maximum, and G3 just before minimum brightness. [12]

A visual band light curve for S Sagittae, adapted from Kiss (1998) SSgeLightCurve.png
A visual band light curve for S Sagittae, adapted from Kiss (1998)

S Sagittae is a yellow-white supergiant that varies between spectral types F6Ib and G5Ib. It is around six or seven times as massive and five thousand times as luminous as the Sun and is located around 2,000 light-years away from Earth. [2] Its radius is 58.5 times that of the Sun. [7] The radius, temperature, luminosity, and colour are all variable as the star pulsates during its eight-day period. The period is slowly increasing. [2]

S Sagittae has been reported as a double or triple system with a hotter main sequence star companion in a 676-day orbit. The companion, and its own possible fainter companion, are only detectable from radial velocity changes in the spectral lines of the Cepheid primary and an ultraviolet excess. Analysis of the spectrum indicates a star of spectral type A7V to F0V, and 1.5 to 1.7 times as massive as the Sun. However, as the mass of the companion is greater than 2.8 solar masses, this strongly suggests this companion is itself a binary star. [6]

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<span class="mw-page-title-main">WZ Sagittae</span> Variable star in the constellation Sagitta

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<span class="mw-page-title-main">AX Circini</span> Binary star system in the constellation Circinus

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<span class="mw-page-title-main">U Vulpeculae</span> Variable star in the constellation Vulpecula

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<span class="mw-page-title-main">V473 Lyrae</span> Star in the constellation Lyra

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<span class="mw-page-title-main">X Cygni</span> Variable star in the constellation Cygnus

X Cygni is a variable star in the northern constellation of Cygnus, abbreviated X Cyg. This is a Delta Cephei variable that ranges in brightness from an apparent visual magnitude of 5.85 down to 6.91 with a period of 16.386332 days. At it brightest, this star is dimly visible to the naked eye. The distance to this star is approximately 628 light years based on parallax measurements. It is drifting further away with a radial velocity of 8.1 km/s. This star is a likely member of the open cluster Ruprecht 173.

References

  1. 1 2 3 4 5 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.
  2. 1 2 3 4 5 6 7 Kiss, L. L. (1998). "A photometric and spectroscopic study of the brightest northern Cepheids – I. Observations". Monthly Notices of the Royal Astronomical Society. 297 (3): 825–838. Bibcode:1998MNRAS.297..825K. doi: 10.1046/j.1365-8711.1998.01559.x .
  3. ↑ Payne-Gaposchkin, Cecilia (1984). "Der Seufzer des Fusionsofens – Die Cepheiden". Sterne und Sternhaufen (in German). pp. 96–110. doi:10.1007/978-3-322-86266-2_8. ISBN   978-3-528-08486-8.
  4. ↑ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv: astro-ph/0406573 . Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID   119387088.
  5. 1 2 Kovtyukh, V. V.; Chekhonadskikh, F. A.; Luck, R. E.; Soubiran, C.; Yasinskaya, M. P.; Belik, S. I. (2010). "Accurate luminosities for F-G supergiants from Fe ii / Fe i line depth ratios" (PDF). Monthly Notices of the Royal Astronomical Society. 408 (3): 1568. Bibcode:2010MNRAS.408.1568K. doi: 10.1111/j.1365-2966.2010.17217.x .
  6. 1 2 Evans, Nancy R.; Welch, Douglas L.; Slovak, Mark H.; Barnes, Thomas G.; Moffett, Thomas J. (1993). "The orbit and companion of the Cepheid S SGE – A probable triple system". Astronomical Journal. 106: 1599. arXiv: astro-ph/9706292 . Bibcode:1993AJ....106.1599E. doi:10.1086/116750.
  7. 1 2 Moskalik, P.; Gorynya, N. A. (2005). "Mean Angular Diameters and Angular Diameter Amplitudes of Bright Cepheids". Acta Astronomica. 55: 247. arXiv: astro-ph/0507076 . Bibcode:2005AcA....55..247M.
  8. ↑ McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental parameters and infrared excesses of Hipparcos stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv: 1208.2037 . Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. S2CID   118665352.
  9. ↑ Andrievsky, S. M.; Kovtyukh, V. V.; Luck, R. E.; Lépine, J. R. D.; Bersier, D.; MacIel, W. J.; Barbuy, B.; Klochkova, V. G.; Panchuk, V. E.; Karpischek, R. U. (2002). "Using Cepheids to determine the galactic abundance gradient. I. The solar neighbourhood". Astronomy and Astrophysics. 381: 32–50. arXiv: astro-ph/0112525 . Bibcode:2002A&A...381...32A. doi:10.1051/0004-6361:20011488. S2CID   15499813.
  10. ↑ Skowron, Dorota M.; et al. (2019). "A three-dimensional map of the Milky Way using classical Cepheid variable stars". Science. 365 (6452): 478–482. arXiv: 1806.10653 . Bibcode:2019Sci...365..478S. doi:10.1126/science.aau3181. PMID   31371611. S2CID   199064609.
  11. ↑ Aldrich, John A. (1932). "A study of S Sagittae". Publications of the Observatory of the University of Michigan. 4 (5): 75–92. Bibcode:1932POMic...4...75A.
  12. ↑ Shapley, Harlow (1916). "The variations in spectral type of twenty Cepheid variables". The Astrophysical Journal. 44 (`): 273–91. Bibcode:1916ApJ....44..273S. doi: 10.1086/142295 .
  13. ↑ Kiss, Laszlo L. (July 1998). "A photometric and spectroscopic study of the brightest northern Cepheids - I. Observations". Monthly Notices of the Royal Astronomical Society. 297 (3): 825. Bibcode:1998MNRAS.297..825K. doi: 10.1046/j.1365-8711.1998.01559.x .
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