Pi Lupi
π Lupi (Latinised to Pi Lupi) is a multiple star system in the southern constellation Lupus. Two components form a wide binary pair with an orbital period of 517 years and a semimajor axis of 1.59″. They belong to the Upper Centaurus Lupus component of the Sco–Cen complex.
A light curve for Pi Lupi, adapted from Sharma et al. (2022) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lupus |
| Right ascension | 15h 05m 07.08596s |
| Declination | −47° 03′ 04.4976″ |
| Apparent magnitude (V) | 3.89 |
| Characteristics | |
| Spectral type | B5V + B5IV |
| U−B color index | −0.59 |
| B−V color index | −0.14 |
| Astrometry | |
| Radial velocity (Rv) | +4.50 km/s |
| Proper motion (μ) | RA: −22.98 mas/yr Dec.: −22.81 mas/yr |
| Parallax (π) | 7.36 ± 0.55 mas |
| Distance | 440 ± 30 ly (140 ± 10 pc) |
| Details | |
| A | |
| Mass | 4.5 M☉ |
| Surface gravity (log g) | 4.5 cgs |
| Temperature | 16,000 K |
| Rotational velocity (v sin i) | 10 km/s |
| B | |
| Mass | 4.7 M☉ |
| Temperature | 14,000 K |
| Rotational velocity (v sin i) | 10 km/s |
| Age | 14 Myr |
| Other designations | |
| π Lupi A: HD 133242, HR 5605 | |
| π Lupi B: HD 133243, HR 5606 | |
| Database references | |
| SIMBAD | data |
| A | |
| B | |
At least one of the components is a spectroscopic binary and produces eclipses 15.5 days apart, making it an eclipsing binary. There are also other brightness variations with a period of 16 hours that are likely to be pulsations of the Slowly pulsating B-type star. The eclipses are shallow, with the brightness dropping by only 1% or about 0.01 magnitudes. The amplitude of the pulsations is even smaller.
π Lupi A (HR 5605, HD 133242) has been classified as a spectroscopic binary by at least two studies, but both components may be spectroscopic binaries.