| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pegasus |
| Right ascension | 21h 56m 23.984s[1] |
| Declination | +21° 14′ 23.49″[1] |
| Apparent magnitude (V) | +6.39[2] |
| Characteristics | |
| Spectral type | M1III[3] |
| B−V color index | 1.698±0.002[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.79±0.06[3] km/s |
| Proper motion (μ) | RA: 1.433 mas/yr[1] Dec.: 14.675 mas/yr[1] |
| Parallax (π) | 3.0302 ± 0.049 mas[1] |
| Distance | 1,080 ± 20 ly (330 ± 5 pc) |
| Absolute magnitude (MV) | –1.24[3] |
| Details[3] | |
| Mass | 1.6±0.4 M☉ |
| Radius | 57.6±6.5[4] R☉ |
| Luminosity | 729±30[4] L☉ |
| Surface gravity (log g) | 1.6±0.3 cgs |
| Temperature | 4,035±65 K |
| Metallicity [Fe/H] | −0.09±0.16 dex |
| Rotational velocity (v sin i) | 3.6 km/s |
| Age | 2±1.3 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 208527 is a star with an orbiting exoplanet located in the northern constellation of Pegasus. It has a reddish hue and is dimly visible to the naked eye with an apparent visual magnitude of +6.39.[2] The star is located at a distance of approximately 1,080 light years from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +4.8 km/s.[3] It is currently the largest star known to have an exoplanet.
This was once catalogued as a K-type main-sequence star with a stellar classification of K5V, but is now known as an aging red giant with a class of M1III, based on its dimensions and low surface gravity.[3] This indicates that the two-billion year old star has exhausted the supply of hydrogen at its core then cooled and expanded off the main sequence. It has an estimated 1.6[3] times the mass of the Sun but has swollen to 58 times the Sun's radius. The star is radiating 729[4] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,035 K.[3]
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