Pi Lupi
Multiple star system in the constellation Lupus
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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.[3]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lupus |
| Right ascension | 15h 05m 07.08596s[1] |
| Declination | −47° 03′ 04.4976″[1] |
| Apparent magnitude (V) | 3.89[2] |
| Characteristics | |
| Spectral type | B5V + B5IV[3] |
| U−B color index | −0.59[2] |
| B−V color index | −0.14[2] |
| Astrometry | |
| Radial velocity (Rv) | +4.50[4] km/s |
| Proper motion (μ) | RA: −22.98[1] mas/yr Dec.: −22.81[1] mas/yr |
| Parallax (π) | 7.36±0.55 mas[1] |
| Distance | 440 ± 30 ly (140 ± 10 pc) |
| Details | |
| A | |
| Mass | 4.5[5] M☉ |
| Surface gravity (log g) | 4.5[5] cgs |
| Temperature | 16,000[5] K |
| Rotational velocity (v sin i) | 10[5] km/s |
| B | |
| Mass | 4.7[5] M☉ |
| Temperature | 14,000[5] K |
| Rotational velocity (v sin i) | 10[5] km/s |
| Age | 14[5] Myr |
| Other designations | |
| CD−46°9773, HIP 73807, SAO 225426 | |
| 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.[6]
π Lupi A (HR 5605, HD 133242) has been classified as a spectroscopic binary by at least two studies,[7][8] but both components may be spectroscopic binaries.[9]