Kappa Scorpii (Mula)
Kappa Scorpii (Mula) is a star in the constellation Scorpius, magnitude 2.4.
Two hot blue giants in the Scorpion’s tail, carrying the Sumerian word for “scorpion”.
Kappa Scorpii has borne an ancient name: Girtab, the Sumerian word for “scorpion”, which survived through Babylonian star catalogues. It first belonged to a group of four stars in the tail, this one among them. A 1971 NASA catalogue listed the star instead as Mula, after an Indian nakshatra in the same part of the sky.
It is really two hot blue-white stars, too close together to separate in a telescope, circling each other every 195 days. The larger, about 11 times the Sun’s mass and nearly 7 times its width, is a Beta Cephei variable star: it pulses about five times a day, roughly every 4.8 hours. It also spins quickly, turning once in only 1.9 days. Its partner, of about 10 solar masses, is only a little smaller.
Kappa Scorpii (Mula) is 480 light-years away: the light we see from it set off around 1545, around the time Copernicus put the Sun at the centre of the Solar System.
Did you know?
- The budgerigar. The Kamilaroi and Euahlayi Aboriginal peoples of New South Wales call this star Gidjirrigaa, the budgerigar.
- On Brazil’s flag. Kappa Scorpii is one of the stars on the flag of Brazil, where it represents the state of Paraíba.
- Seventh star of the Tail. In Chinese astronomy it is Wěi Xiù qī, the Seventh Star of the Tail, a lunar mansion made from the Scorpion’s curving tail.
A blue-white 2nd-magnitude star in the curl of the Scorpion’s tail, a few degrees east of Shaula and Lesath, the bright pair that marks the sting. Binoculars show all three in one view.
When and where to see it
It is best placed in the evening sky around July, when it crosses the meridian at about 10 pm local time (around midnight in June). It can be seen from everywhere south of 51°N and never sets south of 51°S.
At its highest it stands 1° up from 50°N, 16° up from 35°N, 51° up from the equator, 86° up from 35°S.
Facts
- Type
- Star
- Constellation
- Scorpius
- Designations
- Mula, κ Sco, HR 6580, HD 160578, HIP 86670
- Magnitude
- 2.4
- Position
- RA 17h 42.5m, Dec −39° 2′ (J2000)
- Spectral type
- B1.5III
- Colour
- blue-white (B−V -0.18)
- Distance
- 480 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Kappa Scorpii (Mula) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.