Astronomy:HD 208527
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| 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 or K5V[3][4] |
| B−V color index | 1.698±0.002[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.79±0.06[4] km/s |
| Proper motion (μ) | RA: 1.433[1] mas/yr Dec.: 14.675[1] mas/yr |
| Parallax (π) | 3.0302 ± 0.049[1] mas |
| Distance | 1,080 ± 20 ly (330 ± 5 pc) |
| Absolute magnitude (MV) | –1.24[4] |
| Details[4] | |
| Mass | 1.6±0.4 M☉ |
| Radius | 57.6±6.5[5] R☉ |
| Luminosity | 729±30[5] 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 |
| Extrasolar Planets Encyclopaedia | 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.[4]
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.[4] 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[4] times the mass of the Sun but has swollen to 58 times the Sun's radius. The star is radiating 729[5] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,035 K.[4]
Planetary system
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)".
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.[3] Along with HD 220074 b this is one of the first two planets proposed around a red giant.
| 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
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 3.2 "hd_208527_b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/hd_208527_b--1223/.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Lee, B.-C. et al. (2012). "Planetary companions orbiting M giants HD 208527 and HD 220074". Astronomy & Astrophysics 549: A2. doi:10.1051/0004-6361/201220301. Bibcode: 2013A&A...549A...2L.
- ↑ 5.0 5.1 5.2 Johns, Daniel et al. (November 2018). "Revised Exoplanet Radii and Habitability Using Gaia Data Release 2". The Astrophysical Journal Supplement Series 239 (1): 14. doi:10.3847/1538-4365/aae5fb. 14. Bibcode: 2018ApJS..239...14J.
- ↑ "HD 208527". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+208527.
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