Uridim (Alpha Lupi)
Uridim (Alpha Lupi) is a star in the constellation Lupus, magnitude 2.3.
The Wolf’s brightest star — a pulsing blue giant that carries a revived Sumerian name.
The Sumerians had a name for this constellation, UR.IDIM, written Uridimmu in later Akkadian. In 2024 the International Astronomical Union revived it as Uridim, the official name of the Wolf’s brightest star.
It is a blue-white giant about ten times the Sun’s mass, shining 18,000 times as brightly with a surface near 24,550 kelvin. In 1956 Bernard Pagel and colleagues found that it pulses: every 7 hours and 6 minutes it brightens and fades by about 5 per cent, a Beta Cephei variable star. A fainter companion of about 2.25 solar masses was found in 2023, on an orbit expected to take about a decade.
Uridim belongs to the Upper Centaurus–Lupus group, a family of stars some 16 to 20 million years old within the Scorpius–Centaurus association, the nearest gathering of massive young stars to the Sun. Stars of this family blew the Local Bubble, the cavity of hot gas the Sun now travels through. Uridim itself is one of the nearest candidates to explode as a supernova.
Uridim (Alpha Lupi) is 460 light-years away: the light we see from it set off around 1565, 25 years after Copernicus put the Sun at the centre of the Solar System.
Did you know?
- The South Gate that wasn’t. R. H. Allen gave it the Chinese name Yang Mun, “the South Gate”. But in Chinese astronomy that gate is made by two stars of the Centaur.
- An imperial guard. Its Chinese name is in fact Qí Guān shí, the Tenth Star of the Imperial Guards, an asterism spread across Lupus.
A blue-white 2nd-magnitude star, the brightest in Lupus, about 13 degrees due north of Alpha Centauri. Compare it with orange Menkent to the north-west: similar brightness, very different colour.
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 43°N and never sets south of 43°S.
At its highest it stands below the horizon from 50°N, 8° up from 35°N, 43° up from the equator, 78° up from 35°S.
Facts
- Type
- Star
- Constellation
- Lupus
- Designations
- Alpha Lupi, Men, α Lup, HR 5469, HD 129056, HIP 71860
- Magnitude
- 2.3
- Position
- RA 14h 41.9m, Dec −47° 23′ (J2000)
- Spectral type
- B1.5III
- Colour
- blue-white (B−V -0.16)
- Distance
- 460 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Uridim (Alpha Lupi) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.