Gamma Sagittae

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Gamma Sagittae
Diagram showing star positions and boundaries of the Sagitta constellation and its surroundings
Cercle rouge 100%.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
Characteristics
Spectral type M0III
Astrometry
Radial velocity (Rv) -34.00 ± 0.2[1] km/s
Proper motion (μ) RA: 66.21 ± 0.14[2] mas/yr
Dec.: 22.22 ± 0.12[2] mas/yr
Parallax (π) 12.62 ± 0.18[2] mas
Distance 258 ± 4 ly
(79 ± 1 pc)
Absolute magnitude (MV) -2.13[3]
Details
Radius 55[3] R
Luminosity 562±75[3] L
Temperature 3805[3] K
Metallicity -0.14[3]
Other designations
γ Sagittae, γ Sge, Gamma Sge, 12 Sagittae, BD+19 4229, FK5 752, GC 27672, HD 189319, HIP 98337, HR 7635, PPM 137344, SAO 105500

Gamma Sagittae (Gamma Sge, γ Sagittae, γ Sge) is the brightest star in constellation Sagitta and is a red giant with an apparent magnitude of +3.47. It is approximately 258 ± 4 light years from Earth. It has been classified as anywhere from spectral type K5III to M0III.[4]

It radiates at a power 640 times that of Sun. With a mass of 2.5 times that of the Sun, Gamma Sagittae began life 750 million years ago as a white class B9 star.[4]

Naming[edit]

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, γ Sagittae itself is known as 左旗五 (Zuǒ Qí wǔ, English: the Fifth Star of Left Flag.)[5]

References[edit]

  1. ^ a b c SIMBAD, Gamma Sagittae (accessed 22 May 2015)
  2. ^ a b c 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. 
  3. ^ 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. A100. 
  4. ^ a b Kaler, James B. "GAMMA SGE (Gamma Sagittae)". Stars. University of Illinois. Retrieved 22 May 2015. 
  5. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日