Gamma Sagittae

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γ Sagittae
Sagitta constellation map.svg
Red circle.svg
Location of γ Sagittae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagitta
Right ascension 19h 58m 45.42863s[1]
Declination +19° 29′ 31.7281″[1]
Apparent magnitude (V) +3.47[2]
Evolutionary stage Red Giant
Spectral type M0 III[3][4][5]
U−B color index +1.93[2]
B−V color index +1.57[2]
Radial velocity (Rv)−34.0±0.2[6] km/s
Proper motion (μ) RA: 66.21±0.14[1] mas/yr
Dec.: 22.22±0.12[1] mas/yr
Parallax (π)11.3375 ± 0.1652 mas[7]
Distance288 ± 4 ly
(88 ± 1 pc)
Absolute magnitude (MV)−1.11[8]
0.9±0.2 M[10]
1.3±0.4 M[11]
1.37±2.00 M[12]
1.77[4] M
Radius55.13±3.29[13] R
Luminosity (bolometric)562±75[13] L
Surface gravity (log g)1.71[14] cgs
Temperature3,862±40[4] K
Metallicity [Fe/H]−0.14[13] dex
Age2.35[4] Gyr
Other designations
γ Sge, 12 Sagittae, BD+19° 4229, FK5 752, GC 27672, HD 189319, HIP 98337, HR 7635, SAO 105500, PPM 137344
Database references

Gamma Sagittae, Latinized from γ Sagittae, is the brightest star in northern constellation of Sagitta. A single star,[15] it is visible to the naked eye with an apparent visual magnitude of +3.47.[2] Based upon an annual parallax shift of 12.62 mas as seen from Earth, it is located about 288 light-years from the Sun. It is moving closer to the Sun with a radial velocity of −34 km/s.[6]

This is a red giant star with a stellar classification of M0 III.[11][16] It is most likely (94% chance) on the red-giant branch of its evolutionary lifespan, fusing hydrogen along a shell to generate energy.[9][12] The star is around 2.35[4] billion years old with roughly 55[13] times the Sun's radius. Mass estimates range from 0.9[9][10] to 1.8[4] times the mass of the Sun. It is radiating about 562[13] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,862 K.[4]


In Chinese, 左旗 (Zuǒ Qí), meaning Left Flag, refers to an asterism consisting of γ Sagittae, α Sagittae, β Sagittae, δ Sagittae, ζ Sagittae, 13 Sagittae, 11 Sagittae, 14 Sagittae and ρ Aquilae. Consequently, the Chinese name for γ Sagittae itself is 左旗五 (Zuǒ Qí wǔ, English: the Fifth Star of Left Flag).[17]


  1. ^ a b c d van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics. 474 (2): 653–64. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ a b c d 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. ^ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  4. ^ a b c d e f g Luck, R. Earle (2015). "Abundances in the Local Region. I. G and K Giants". Astronomical Journal. 150 (3). 88. arXiv:1507.01466. Bibcode:2015AJ....150...88L. doi:10.1088/0004-6256/150/3/88. S2CID 118505114.
  5. ^ Skiff, B. A. (2014). "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)". VizieR On-line Data Catalog: B/Mk. Originally Published in: Lowell Observatory (October 2014). 1. Bibcode:2014yCat....1.2023S.
  6. ^ a b Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
  7. ^ Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  8. ^ Setiawan, J.; et al. (July 2004), "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch", Astronomy and Astrophysics, 421: 241–254, Bibcode:2004A&A...421..241S, doi:10.1051/0004-6361:20041042-1.
  9. ^ a b c Stock, Stephan; Reffert, Sabine; Quirrenbach, Andreas; Hauschildt, P. (2018). "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy and Astrophysics. 616: A33. arXiv:1805.04094. Bibcode:2018A&A...616A..33S. doi:10.1051/0004-6361/201833111. S2CID 119361866.
  10. ^ a b Neilson, Hilding R.; Lester, John B. (2008). "Determining parameters of cool giant stars by modeling spectrophotometric and interferometric observations using the SAtlas program". Astronomy and Astrophysics. 490 (2): 807–10. arXiv:0809.1875. Bibcode:2008A&A...490..807N. doi:10.1051/0004-6361:200810627. S2CID 1586125.
  11. ^ a b Wittkowski, M.; Hummel, C. A.; Aufdenberg, J. P.; Roccatagliata, V. (December 2006), "Tests of stellar model atmospheres by optical interferometry. III. NPOI and VINCI interferometry of the M0 giant γ Sagittae covering 0.5-2.2 μm", Astronomy and Astrophysics, 460 (3): 843–853, arXiv:astro-ph/0610149, Bibcode:2006A&A...460..843W, doi:10.1051/0004-6361:20065853, S2CID 15437314.
  12. ^ a b Reffert, Sabine; Bergmann, Christoph; Quirrenbach, Andreas; Trifonov, Trifon; Künstler, Andreas (2015). "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity". Astronomy & Astrophysics. 574: A116. arXiv:1412.4634. Bibcode:2015A&A...574A.116R. doi:10.1051/0004-6361/201322360. hdl:10722/215277. S2CID 59334290.
  13. ^ a b c d e Piau, L.; Kervella, P.; Dib, S.; Hauschildt, P. (2011). "Surface convection and red-giant radius measurements". Astronomy and Astrophysics. 526: 12. arXiv:1010.3649. Bibcode:2011A&A...526A.100P. doi:10.1051/0004-6361/201014442. S2CID 118533297. A100.
  14. ^ Bluhm, P.; Jones, M. I.; Vanzi, L.; Soto, M. G.; Vos, J.; Wittenmyer, R. A.; Drass, H.; Jenkins, J. S.; Olivares, F.; Mennickent, R. E.; Vučković, M.; Rojo, P.; Melo, C. H. F. (2016). "New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems". Astronomy & Astrophysics. 593: A133. arXiv:1608.08260. Bibcode:2016A&A...593A.133B. doi:10.1051/0004-6361/201628459. S2CID 56087624.
  15. ^ 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  16. ^ Strassmeier, K. G.; Ilyin, I.; Weber, M. (2018). "PEPSI deep spectra. II. Gaia benchmark stars and other M-K standards". Astronomy and Astrophysics. 612: A45. arXiv:1712.06967. Bibcode:2018A&A...612A..45S. doi:10.1051/0004-6361/201731633. S2CID 119244142.
  17. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日

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