HD 189733
HD 189733, also catalogued as V452 Vulpeculae, is a binary star system 64.5 light-years (19.8 parsecs) away in the constellation of Vulpecula (the Fox). The primary star is suspected to be an orange dwarf star, while the secondary star is a red dwarf star. Given that this system has the same visual magnitude as HD 209458, it promises much for the study of close transiting extrasolar planets. The star can be found with binoculars 0.3 degrees east of the Dumbbell Nebula (M27).
The location of the HD 189733 system. | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Vulpecula |
| HD 189733 A | |
| Right ascension | 20h 00m 43.71294s |
| Declination | +22° 42′ 39.0732″ |
| Apparent magnitude (V) | 7.676 |
| HD 189733 B | |
| Right ascension | 20h 00m 42.97791s |
| Declination | +22° 42′ 34.1785″ |
| Apparent magnitude (V) | ~10 |
| Characteristics | |
| Spectral type | K1.5V/M |
| Apparent magnitude (B) | 8.609 ±0.016/ |
| Apparent magnitude (J) | 6.07/10.116 ±0.041 |
| Apparent magnitude (H) | 5.59/9.545 ±0.086 |
| Apparent magnitude (K) | 5.54/9.323 ±0.027 |
| Variable type | BY Draconis |
| Astrometry | |
| HD 189733 A | |
| Radial velocity (Rv) | −2.53±0.12 km/s |
| Proper motion (μ) | RA: −3.208(11) mas/yr Dec.: −250.323(14) mas/yr |
| Parallax (π) | 50.5668 ± 0.0162 mas |
| Distance | 64.50 ± 0.02 ly (19.776 ± 0.006 pc) |
| Absolute magnitude (MV) | 6.2 |
| HD 189733 B | |
| Radial velocity (Rv) | 1.46±1.21 km/s |
| Proper motion (μ) | RA: −12.193(9) mas/yr Dec.: −253.993(12) mas/yr |
| Parallax (π) | 50.6291 ± 0.0136 mas |
| Distance | 64.42 ± 0.02 ly (19.751 ± 0.005 pc) |
| Orbit | |
| Companion | HD 189733 B |
| Period (P) | 3,200 yr |
| Semi-major axis (a) | 11.38" (216 AU) |
| Details | |
| Mass | 0.846+0.068 −0.049 M☉ |
| Radius | 0.805±0.016 R☉ |
| Luminosity | 0.328±0.011 L☉ |
| Surface gravity (log g) | 4.56±0.03 cgs |
| Temperature | 4875±43 K |
| Metallicity [Fe/H] | −0.03±0.08 dex |
| Rotation | 11.953±0.009 days |
| Age | 4.3±2.8 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | A |
| B | |
| Exoplanet Archive | data |
As of 2005, it has been confirmed that an exoplanet, HD 189733 b, orbits the primary star within the system.
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