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.^[4]

π Lupi

A light curve for Pi Lupi, adapted from Sharma et al. (2022)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Lupus
Right ascension	15h 05m 07.08596s[2]
Declination	−47° 03′ 04.4976″[2]
Apparent magnitude (V)	3.89[3]
Characteristics
Spectral type	B5V + B5IV[4]
U−B color index	−0.59[3]
B−V color index	−0.14[3]
Astrometry
Radial velocity (Rv)	+4.50[5] km/s
Proper motion (μ)	RA: −22.98[2] mas/yr Dec.: −22.81[2] mas/yr
Parallax (π)	7.36±0.55 mas[2]
Distance	440 ± 30 ly (140 ± 10 pc)
Details
A
Mass	4.5[6] M☉
Surface gravity (log g)	4.5[6] cgs
Temperature	16,000[6] K
Rotational velocity (v sin i)	10[6] km/s
B
Mass	4.7[6] M☉
Temperature	14,000[6] K
Rotational velocity (v sin i)	10[6] km/s
Age	14[6] 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.^[1]

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]