Back سعد البهام Arabic Baham (estrella) AST Baham Catalan Biham (Stern) German Baham (estrella) Spanish تتا پگاسوس Persian Theta Pegasi French Theta Pegasi ID Theta Pegasi Italian ペガスス座シータ星 Japanese

Theta Pegasi

Theta Pegasi
Location of θ Pegasi (circled)
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) +3.52[2]
Characteristics
Evolutionary stage main sequence[3]
Spectral type A2V[4] + M4-5.5[5]
B−V color index 0.086±0.002[2]
Astrometry
Radial velocity (Rv)−7.9±2.4[2] km/s
Proper motion (μ) RA: +282.18[1] mas/yr
Dec.: +30.46[1] mas/yr
Parallax (π)35.34 ± 0.85 mas[1]
Distance92 ± 2 ly
(28.3 ± 0.7 pc)
Absolute magnitude (MV)1.24[2]
Orbit[5]
Semi-major axis (a)6.55+3.0
−0.48 au
Eccentricity (e)0.54+0.28
−0.15
Inclination (i)66.7+8.5
−14°
Details
θ Peg A
Mass2.09 ± 0.16[6] M☉
Radius2.623±0.083[5] R☉
Luminosity23.7±1.1[4] L☉
Surface gravity (log g)3.95[6] cgs
Temperature7872±82[4] K
Metallicity [Fe/H]−0.38[4] dex
Rotational velocity (v sin i)136[6] km/s
Age448[6] Myr
θ Peg B
Mass0.280+0.18
−0.059[5] M☉
Surface gravity (log g)5.5[5] cgs
Temperature3200[5] K
Other designations
Biham, θ Peg, 26 Peg, FK5 834, HD 210418, HIP 109427, HR 8450, SAO 127340[7]
Database references
SIMBADdata

θ Pegasi, Latinized as Theta Pegasi, is a single[8] star in the equatorial constellation of Pegasus, lying about 7.5 degrees southwest of Enif.[9] It has the traditional name Biham /ˈbaɪ.æm/,[10][11] and the Flamsteed designation 26 Pegasi. This object is visible to the naked eye as a white-hued point of light with an apparent visual magnitude of +3.52.[2] The system is located 92 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −8 km/s.[2]

This object an A-type main-sequence star with a stellar classification of A2V.[4] It is 448[6] million years old with a high rate of spin, showing a projected rotational velocity of 136 km/s.[6] This star has 2.09[5] times the mass of the Sun and 2.6[12] times the Sun's radius. It is radiating 25 times the luminosity of the Sun from its outer envelope at an effective temperature of 7,951 K.[12] The star appears to display a slight infrared excess.[13]

θ Pegasi was suspected of being a binary star due to an acceleration detected by Hipparcos. In 2021, a low-mass companion star was discovered, associated with θ Pegasi.[5] It is a red dwarf with a spectral type of M4 to M5.5, and a luminosity of 0.5% that of the Sun.[5] The orbit around the primary is estimated to be moderately eccentric, at 0.54, and has a semimajor axis of 6.55 au.[5]

  1. ^ a b c d e Cite error: The named reference van Leeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference zorec2012 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference apj771_1_40 was invoked but never defined (see the help page).
  5. ^ a b c d e f g h i j Steiger, Sarah; et al. (2021). "SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy". The Astronomical Journal. 162 (2): 44. arXiv:2103.06898. Bibcode:2021AJ....162...44S. doi:10.3847/1538-3881/ac02cc. S2CID 244399987.
  6. ^ a b c d e f Cite error: The named reference David2015 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference DeRosa2014 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Mollise2012 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Kunitzsch was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference IAU-CSN was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference apj746_1_101 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Nuñez2017 was invoked but never defined (see the help page).
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