Psi Pegasi

Psi Pegasi
Location of ψ Pegasi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pegasus
Right ascension 23h 57m 45.52681s[1]
Declination 25° 08′ 29.0480″[1]
Apparent magnitude (V) 4.66[2]
Characteristics
Spectral type M3III[3]
U−B color index +1.66[2]
B−V color index +1.59[2]
Variable type suspected[4]
Astrometry
Radial velocity (Rv)−6.59±0.23[5] km/s
Proper motion (μ) RA: −35.24[1] mas/yr
Dec.: −31.60[1] mas/yr
Parallax (π)6.85 ± 0.24 mas[1]
Distance480 ± 20 ly
(146 ± 5 pc)
Absolute magnitude (MV)–1.19[6]
Orbit[7]
Period (P)55.06±11.31 yr
Semi-major axis (a)0.170±0.016″
Eccentricity (e)0.19±0.10
Inclination (i)65.6±2.2°
Longitude of the node (Ω)46.6±2.3°
Periastron epoch (T)2,001.83±8.81
Argument of periastron (ω)
(secondary)		159.7±11.9°
Details
Radius98±6[8] R☉
Luminosity960[6] L☉
Temperature3,882[9] K
Other designations
ψ Peg, 84 Pegasi, NSV 14777, BD+24°4865, FK5 1629, GC 33230, HD 224427, HIP 118131, HR 9064, SAO 91611, WDS J23578+2508AB[10]
Database references
SIMBADdata

Psi Pegasi, which is Latinized from ψ Pegasi, is a binary star system within the great square[11] in the northern constellation of Pegasus. It has a red hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.66.[2] This object is located at a distance of approximately 476 light-years away from the Sun based on parallax,[1] but is drifting closer with a radial velocity of −6.6 km/s.[5]

A visual band light curve for Psi Pegasi, plotted from data published by Tabur et al. (2009)[12]

The orbital elements for this system were computed for the first time in 2004 based on interferometric observations, yielding an orbital period of roughly 55 years and an eccentricity of about 0.19.[7][13][14] The visible component is an aging red giant star on the asymptotic giant branch[15] with a stellar classification of M3III.[3] It is a suspected variable, probably semiregular, with its magnitude varying from 4.63 to 4.69[4][16] over periods of 37.4 and 118.9 days.[12] With the supply of hydrogen exhausted at its core, the star has cooled and expanded to around 98[8] times the Sun's radius. It is radiating 960[6] times the luminosity of the Sun from its bloated photosphere at an effective temperature of 3,882 K.[9]

  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. ^ a b Cite error: The named reference perkins1989 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Famaey2005 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference XHIP was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Olevic2004 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference ArroyoTorres2014 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Perez2011 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Harrington2010 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Tabur2009 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Malkov2012 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference WDS was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Eggen1992 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference aavso was invoked but never defined (see the help page).