Beta Lupi (KeKouan)
Beta Lupi (KeKouan) is a star in the constellation Lupus, magnitude 2.7.
A pulsing blue-white giant beside the wreck of history’s brightest supernova.
Just over a degree from Beta Lupi lies the wreck of the supernova of 1006, the brightest exploding star in recorded history. Beta Lupi may one day explode too. At about 8.8 times the Sun’s mass it sits close to the dividing line: it might die as a supernova, or settle down as a white dwarf.
For now it is a hot giant, around 24,000 K at the surface and about 25 million years old, nearing the end of its hydrogen-burning life on its way to becoming a red supergiant. It also pulsates: it is a Beta Cephei variable with several rhythms at once, the strongest repeating about every five and a half hours.
It belongs to the Scorpius–Centaurus association, the nearest family of massive stars to the Sun, born together and still moving through space as a group.
Beta Lupi (KeKouan) is 380 light-years away: the light we see from it set off around 1645, 35 years after Galileo first turned a telescope to the sky.
Did you know?
- A name via France. Its old European name, Ke Kwan or KeKouan, comes from a French rendering of the Chinese Qí Guān, the Imperial Guards, a group in which Beta Lupi is the fourth star.
- On the move. Beta Lupi shifts across the sky by more than 50 milliarcseconds a year — a high proper motion that hints at a fast sideways speed through space.
A blue-white star of magnitude 2.7, the second-brightest in Lupus, the Wolf, about 5 degrees north-east of Alpha Lupi. Just over a degree to its north-north-east lies the place where the supernova of 1006 blazed.
When and where to see it
It is best placed in the evening sky around June, when it crosses the meridian at about 10 pm local time (around midnight in May). It can be seen from everywhere south of 47°N and never sets south of 47°S.
At its highest it stands below the horizon from 50°N, 12° up from 35°N, 47° up from the equator, 82° up from 35°S.
Facts
- Type
- Star
- Constellation
- Lupus
- Designations
- KeKouan, β Lup, HR 5571, HD 132058, HIP 73273
- Magnitude
- 2.7
- Position
- RA 14h 58.5m, Dec −43° 8′ (J2000)
- Spectral type
- B2IV
- Colour
- blue-white (B−V -0.22)
- Distance
- 380 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Beta Lupi (KeKouan) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.