Pi1 Pegasi
Star in the constellation Pegasus
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Pi1 Pegasi, Latinized from π1 Pegasi, is a star in the constellation Pegasus. Based upon changes to the proper motion of the visible component, this is a probable astrometric binary.[8] It has a yellow hue and is dimply visible to the naked eye with a combined apparent visual magnitude of +5.58.[2] The system is located approximately 319 light years distant from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +5 km/s.[4]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 22h 09m 13.61893s[1] |
| Declination | +33° 10′ 20.4778″[1] |
| Apparent magnitude (V) | +5.58[2] |
| Characteristics | |
| Spectral type | G8IIIb[3] |
| B−V color index | +0.985±0.003[2] |
| Astrometry | |
| Radial velocity (Rv) | +5.1±0.9[4] km/s |
| Proper motion (μ) | RA: −48.117[1] mas/yr Dec.: −73.408[1] mas/yr |
| Parallax (π) | 10.2111±0.1137 mas[1] |
| Distance | 319 ± 4 ly (98 ± 1 pc) |
| Absolute magnitude (MV) | 0.84[5] |
| Details | |
| Radius | 11.00+0.51 −0.83[1] R☉ |
| Luminosity | 62.8±0.8[1] L☉ |
| Surface gravity (log g) | 2.7[6] cgs |
| Temperature | 4,898+196 −110[1] K |
| Metallicity [Fe/H] | −0.22[5] dex |
| Rotational velocity (v sin i) | 4[6] km/s |
| Other designations | |
| π1 Peg, 27 Pegasi, BD+32°4349, HD 210354, HIP 109352, HR 8449, SAO 72064[7] | |
| Database references | |
| SIMBAD | data |
The visible component is an aging giant star with a stellar classification of G8IIIb.[3] With the supply of hydrogen exhausted at its core, the star has cooled and expanded to 11 times the Sun's radius.[1] It is radiating 63 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,898 K.[1]