HD 208527
| 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]
Planetary system
[edit]From September 2008 to June 2012, the team B.-C. Lee, I. Han and M.-G. Park observed HD 208527 with "the high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO)".[3]
In 2012, a long-period, wide-orbiting exoplanet was deduced by radial velocity variations. This was published in November, gaining the designation HD 208527 b. Along with HD 220074 b this is one of the first two planets proposed around an M-type red giant.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥9.9±1.7 MJ | 2.1±0.2 | 875.5±5.8 | 0.08±0.04 | — | — |
References
[edit]- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
- ^ a b c d e f g h i j k Lee, B.-C.; et al. (2012). "Planetary companions orbiting M giants HD 208527 and HD 220074". Astronomy & Astrophysics. 549: A2. arXiv:1211.2051. Bibcode:2013A&A...549A...2L. doi:10.1051/0004-6361/201220301. S2CID 73522393.
- ^ a b c Johns, Daniel; et al. (November 2018). "Revised Exoplanet Radii and Habitability Using Gaia Data Release 2". The Astrophysical Journal Supplement Series. 239 (1): 14. arXiv:1808.04533. Bibcode:2018ApJS..239...14J. doi:10.3847/1538-4365/aae5fb. 14.
- ^ "HD 208527". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-11-25.
