31 Pegasi

31 Pegasi
Location of 31 Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension 22h 21m 31.07511s[1]
Declination 12° 12′ 18.6628″[1]
Apparent magnitude (V) 4.99[2]
Characteristics
Spectral type B2IV-Ve[3]
U−B color index -0.81[2]
B−V color index -0.10[2]
Variable type γ Cas
Astrometry
Radial velocity (Rv)−5.30[4] km/s
Proper motion (μ) RA: +6.32[1] mas/yr
Dec.: +4.80[1] mas/yr
Parallax (π)2.01 ± 0.28 mas[1]
Distanceapprox. 1,600 ly
(approx. 500 pc)
Absolute magnitude (MV)−3.61[5]
Details[6]
Mass12.5±0.7 M☉
Luminosity (bolometric)27,925+4,360
−3,770 L☉
Surface gravity (log g)3.71±0.15 cgs
Temperature23,890±740 K
Rotational velocity (v sin i)98±8 km/s
Age15.4±1.3[7] Myr
Other designations
31 Peg, IN Peg, BD+11°4784, FK5 843, GC 31255, HD 212076, HIP 110386, HR 8520, SAO 107854[8]
Database references
SIMBADdata

31 Pegasi is a single[9] star in the northern constellation of Pegasus. It is visible to the naked eye as a dim, blue-white hued point of light with a baseline apparent visual magnitude of 4.99.[2] It is located approximately 1,600 light years away from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −5.3 km/s.[4]

A light curve for IN Pegasi, plotted from Hipparcos data[10]

This is a massive Be star with a stellar classification of B2IV-V.[11] It is a γ Cas variable; a type of shell star with a circumstellar disc of gas surrounding the star at the equator, and ranges from 5.05 up to 4.85 in visual magnitude.[12] It is spinning with a projected rotational velocity of 98 km/s, with the pole being inclined by an estimated angle of 26°±9° to the line of sight from the Earth.[6] The star is 15.4[7] million years old with 12.5[6] times the mass of the Sun. It is radiating around 28,000 times the luminosity of the Sun from its photosphere at an effective temperature of 23,890 K.[6]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Ducati2002 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Hoffleit1991 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference XHIP was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Zorec2016 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Eggleton was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference HipDataAccess was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Lesh1968 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).