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Binary star system in the constellation Centaurus From Wikipedia, the free encyclopedia
HD 109749 is a binary star system about 206 light years away in the constellation of Centaurus. The pair have a combined apparent visual magnitude of 8.08,[2] which is too faint to be visible to the naked eye. The primary component has a close orbiting exoplanet companion. The system is drifting closer with a heliocentric radial velocity of −13.2 km/s.[2]
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Centaurus |
Right ascension | 12h 37m 16.379s[1] |
Declination | −40° 48′ 43.63″[1] |
Apparent magnitude (V) | 8.08[2] |
Characteristics | |
Spectral type | G3 IV[3] or G3 V + K5 V[4] |
B−V color index | 0.714±0.021[2] |
Astrometry | |
Radial velocity (Rv) | −13.24±0.18[2] km/s |
Proper motion (μ) | RA: −157.308 mas/yr[1] Dec.: −6.357 mas/yr[1] |
Parallax (π) | 15.8134 ± 0.0263 mas[1] |
Distance | 206.3 ± 0.3 ly (63.2 ± 0.1 pc) |
Absolute magnitude (MV) | 4.34[2] |
Details | |
HD 109749 A | |
Mass | 1.10[5] M☉ |
Radius | 1.21±0.02[6] R☉ |
Luminosity | 1.55±0.02[6] L☉ |
Surface gravity (log g) | 4.32±0.02[6] cgs |
Temperature | 5,860±39[6] K |
Metallicity [Fe/H] | 0.25±0.05[3] dex |
Rotation | 34 d[3] |
Rotational velocity (v sin i) | 2.5±0.5[3] km/s |
Age | 4.10±0.70[6] Gyr |
HD 109749 B | |
Mass | 0.78[5] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
The primary component, HD 109749 A, is a G-type subgiant star with a spectral type of G3IV,[3] indicating it is an evolved star with a luminosity higher than that of a main sequence star. It has a mass of 1.14 M☉ and a radius of 1.21 R☉. The star is shining with a luminosity of 1.55 L☉ and has an effective temperature of 5,860 K. Evolutionary models estimate an age of 4.1 billion years.[6] HD 109749 A is chromospherically inactive and has a high metallicity, with an iron abundance 178% of Sun's.[3]
The secondary, HD 109749 B, is a K-type main sequence star with an apparent magnitude of 10.3.[8] It has a mass of about 0.78 M☉ and is located at a separation of 8.4 arcseconds, which corresponds to a projected separation of 490 AU.[5] This star has the same proper motion as the primary and seems to be at the same distance, confirming they form a physical binary system.[9]
In 2005, an exoplanet was discovered around HD 109749 A. It was detected by the radial velocity method as part of the N2K Consortium. It is a hot Jupiter with a minimum mass of 0.28 MJ and a semimajor axis of 0.06 AU.[3]
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
Ab | ≥0.27±0.045 MJ | 0.0615±0.004 | 5.239891±0.000099 | 0 (fixed) | — | — |
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