Alpha Horologii
Alpha Horologii (α Horologii) is a solitary orange-hued giant star in the constellation Horologium. It is visible to the naked eye with an apparent visual magnitude of +3.85. Based upon an annual parallax shift of 28.36 mas as seen from the Earth, it is located 115.0±0.5 light-years from the Sun. The star is moving away from the Sun with a radial velocity of +21.6 km/s.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Horologium |
| Right ascension | 04h 14m 00.11445s |
| Declination | −42° 17′ 39.7232″ |
| Apparent magnitude (V) | +3.853 |
| Characteristics | |
| Spectral type | K2 III |
| U−B color index | +1.013 |
| B−V color index | +1.097 |
| Astrometry | |
| Radial velocity (Rv) | +21.6±0.3 km/s |
| Proper motion (μ) | RA: +42.0±0.11 mas/yr Dec.: −203.55±0.12 mas/yr |
| Parallax (π) | 28.36 ± 0.12 mas |
| Distance | 115.0 ± 0.5 ly (35.3 ± 0.1 pc) |
| Absolute bolometric magnitude (Mbol) | +1.08 |
| Details | |
| Mass | 1.55 M☉ |
| Radius | 8 R☉ |
| Luminosity | 37.61 L☉ |
| Temperature | 5,028 K |
| Metallicity [Fe/H] | -0.02 dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
The stellar classification of K2 III indicates this is an evolved giant star of the K class. This means it has consumed the hydrogen at its core and has migrated away from the main sequence, with its outer envelope cooling and expanding in the process. Alpha Horologii has an estimated 1.55 times the mass of the Sun and is radiating 38 times the Sun's luminosity from its photosphere at an effective temperature of 5,028 K. It has swollen to around 11 times the diameter of the Sun, having spent much of its life as a white main sequence star.