Gamma Sagittae

Gamma Sagittae, Latinized from γ Sagittae, is the brightest star in northern constellation of Sagitta. A single star,[11] 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 258 light years from the Sun. It is moving closer to the Sun with a radial velocity of −34 km/s.[6]

γ Sagittae
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]
Characteristics
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]
Astrometry
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)12.62 ± 0.18[1] mas
Distance258 ± 4 ly
(79 ± 1 pc)
Absolute magnitude (MV)−1.11[7]
Details
Mass1.37[8] M☉
Radius55.13±3.29[9] R☉
Luminosity (bolometric)562±75[9] L☉
Surface gravity (log g)1.71[10] cgs
Temperature3,862±40[4] K
Metallicity [Fe/H]−0.14[9] dex
Age2.35[4] Gyr
Other designations
β Sge, 12 Sagittae, BD+19° 4229, FK5 752, GC 27672, HD 189319, HIP 98337, HR 7635, SAO 105500, PPM 137344
Database references
SIMBADdata

This is a red giant star with a stellar classification of M0 III.[12][13] It is most likely on the red-giant branch of its evolutionary lifespan, burning hydrogen in its shell.[14]

It is around 2.35[4] billion years old with an estimated 1.37[8] times the mass of the Sun and roughly 55[9] times the Sun's radius. The star is radiating about 562[9] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,862 K.[4]

Naming

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.)[15]

References
  1. 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.
  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. 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. 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.
  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. 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.
  7. 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.
  8. 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.
  9. 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. A100.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. (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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