BL Crucis
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Crux |
| Right ascension | 12h 27m 28.88s |
| Declination | −58° 59′ 30.4″ |
| Apparent magnitude (V) | 5.38 |
| Characteristics | |
| Spectral type | M4-5III |
| Variable type | semiregular variable |
| Astrometry | |
| Radial velocity (Rv) | 71.7 ± 0.9 km/s |
| Proper motion (μ) | RA: -20.027 ± 0.301 mas/yr Dec.: 3.586 ± 0.268 mas/yr |
| Parallax (π) | 6.8429±0.1942 mas |
| Distance | 480 ± 10 ly (146 ± 4 pc) |
| Other designations | |
| HD 108396, HIP 60781, HR 4739, SAO 239960, CD−58° 4560 | |
| Database references | |
| SIMBAD | data |
BL Crucis is a red giant and a semiregular variable in the constellation of Crux. A 5th magnitude star, it is visible to the naked eye under good observing conditions. Three periods have been detected in its light curve, 30.7, 42.3 and 43.6 days. It is 480 ± 10 light-years distant from Earth.
In 1969, Olin J. Eggen announced that the star, then called HR 4739, is a variable star. It was given its variable star designation, BL Crucis, in 1977.