Phi Pegasi

Phi Pegasi

A light curve for Phi Pegasi, plotted from Hipparcos data[1]
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Pegasus
Right ascension 23h 52m 29.28762s[2]
Declination +19° 07′ 13.0218″[2]
Apparent magnitude (V) 5.107[3]
Characteristics
Evolutionary stage red giant[4]
Spectral type M2.5 IIIb[5]
U−B color index +1.878[3]
B−V color index +1.599[3]
Variable type SRb[6]
Astrometry
Radial velocity (Rv)−7.75±0.15[7] km/s
Proper motion (μ) RA: −7.27[2] mas/yr
Dec.: −35.40[2] mas/yr
Parallax (π)7.05 ± 0.27 mas[2]
Distance460 ± 20 ly
(142 ± 5 pc)
Details
Mass1.57[4] M☉
Radius62.7[8] R☉
Luminosity1,122[4] L☉
Surface gravity (log g)0.81[8] cgs
Temperature3,600[4] K
Metallicity [Fe/H]0.0[4] dex
Other designations
φ Peg, 81 Peg, BD+18°5231, FK5 898, HD 223768, HIP 117718, HR 9036, SAO 108878[9]
Database references
SIMBADdata

φ Pegasi, Latinised as Phi Pegasi, is a solitary,[5] reddish hued star in the northern constellation of Pegasus. With an apparent visual magnitude of around 5.1,[3] it is a faint star that can be seen with the naked eye. Based upon an annual parallax shift of 7.05 mas as seen from Earth,[2] the system is located around 460 light years distant from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.15 due to interstellar dust.[7]

This is an evolved red giant star with a stellar classification of M2.5 IIIb.[5] It is a semiregular variable that ranges between magnitudes 5.11 and 5.17.[6] Hipparcos mission photometry gives an amplitude variation of 0.0148 in magnitude with a frequency of 11.4 cycles per day.[10] It is likely to be a semiregular variable and is tentatively classified as type SRb.[6]

In terms of its right ascension coordinates, φ Pegasi is located very near the line of the vernal equinox and will cross over around the year 3030, due to the precession of the Earth's axis.[11]

  1. ^ Cite error: The named reference CDS was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference GutierrezMoreno1966 was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference charbonnel2020 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference AAVSOphi was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Famaey2005 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference mcdonald2017 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference koen2002 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Kaler2016 was invoked but never defined (see the help page).