R Doradus
R Doradus (HD 29712 or P Doradus) is a red giant variable star in the far-southern constellation Dorado. Its distance from Earth is 178 light-years (55 parsecs). Having a uniform disk diameter of 57±5 mas, it is thought to be the extrasolar star with the largest apparent size as viewed from Earth.
Infrared interferometric image of the star Credit: ESO | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Dorado |
| Right ascension | 04h 36m 45.59127s |
| Declination | −62° 04′ 37.7974″ |
| Apparent magnitude (V) | 4.8–6.6 5.40 |
| Characteristics | |
| Evolutionary stage | AGB |
| Spectral type | M8III:e |
| Apparent magnitude (J) | −2.6 |
| Apparent magnitude (K) | −4.2 |
| U−B color index | +0.86 |
| B−V color index | +1.58 |
| Variable type | SRb |
| Astrometry | |
| Radial velocity (Rv) | +26.1 km/s |
| Proper motion (μ) | RA: −69.36 mas/yr Dec.: −75.78 mas/yr |
| Parallax (π) | 18.31 ± 0.99 mas |
| Distance | 178 ± 10 ly (55 ± 3 pc) |
| Details | |
| Mass | 0.7–1.0 M☉ |
| Radius | 298±21 R☉ |
| Luminosity | 4,350±520 L☉ |
| Surface gravity (log g) | −0.6±0.1 cgs |
| Temperature | 2,710±70 K |
| Metallicity | 0.0 |
| Rotation | 57.5 years |
| Rotational velocity (v sin i) | 1±0.1 km/s |
| Age | 6–14 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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