Theta Pegasi

From Wikipedia, the free encyclopedia
Jump to: navigation, search
θ Pegasi
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Pegasus
Right ascension 22h 10m 11.98528s[1]
Declination +06° 11′ 52.3078″[1]
Apparent magnitude (V) +3.53
Spectral type A2V[2]
Radial velocity (Rv) −7.90[3] km/s
Proper motion (μ) RA: +282.18[1] mas/yr
Dec.: +30.46[1] mas/yr
Parallax (π) 35.34 ± 0.85[1] mas
Distance 92 ± 2 ly
(28.3 ± 0.7 pc)
Mass 1.848[2] M
Radius 2.6225±0.0829[2] R
Luminosity 23.7012±1.1418[2] L
Temperature 7872±82[2] K
Metallicity [Fe/H] −0.38[2] dex
Age 1.1[2] Gyr
Other designations
Baham, 26 Peg, FK5 834, HD 210418, HIP 109427, HR 8450, SAO 127340.

Theta Pegasi (θ Peg) is the Bayer designation for a star in the constellation Pegasus. It has the traditional name Biham or Baham from the phrase s'ad al Biham, "Lucky Stars of the Young Beasts".[4]

In Chinese, 危宿 (Wēi Sù), meaning Rooftop, refers to an asterism consisting of θ Pegasi, α Aquarii and ε Pegasi.[5] Consequently, θ Pegasi itself is known as 危宿二 (Wēi Sù èr, English: the Second Star of Rooftop.)[6]

Theta Pegasi is of spectral class A2 and has apparent magnitude +3.53. It is approximately 97 light years from Earth. This star has 2.6 times the Sun's radius and it is radiating 25 times the luminosity of the Sun from its outer envelope at an effective temperature of 7,951 K.[7]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752free to read, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d e f g Boyajian, Tabetha S.; et al. (July 2013), "Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations", The Astrophysical Journal, 771 (1): 31, arXiv:1306.2974free to read, Bibcode:2013ApJ...771...40B, doi:10.1088/0004-637X/771/1/40, 40.  See Table 3.
  3. ^ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  4. ^ Kaler
  5. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  6. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  7. ^ Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal, 746 (1): 101, arXiv:1112.3316free to read, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101 . See Table 10.