Sargas (Theta Scorpii)
Sargas (Theta Scorpii) is a star in the constellation Scorpius, magnitude 1.9.
The Scorpion’s yellow-white tail star — a giant spun into a flattened shape, perhaps by a stellar merger.
Sargas is a giant star of about three solar masses, shining with some 1,400 times the Sun’s light from a yellow-white surface at about 6,300 K. It spins so fast that it is flattened: about 36 times the Sun’s width across the equator but only 26 times from pole to pole. A spin like that is unusual for a giant, and astronomers think Sargas may have formed when the two stars of a binary merged.
It is not alone, though. In 1991 the Hipparcos satellite found a companion, Theta Scorpii B, only half an arcsecond away. An older report of a fifth-magnitude companion was probably mistaken: later observers could not find it.
The name Sargas may be Sumerian in origin, or Persian for ‘arrowhead’.
Sargas (Theta Scorpii) is 300 light-years away: the light we see from it set off around 1725, 40 years after Isaac Newton published his laws of motion and gravity.
Did you know?
- Timing the water. In Iran the star name Sar Gaz — a possible source of ‘Sargas’ — was used to time farmers’ shares of irrigation water.
- On Brazil’s flag. Sargas appears on the flag of Brazil, where it represents the state of Alagoas.
A bright yellow-white star on the curve of the Scorpion’s tail, set in rich Milky Way star fields. Compare its creamy colour with blue-white Shaula, near the tail’s tip.
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 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
- Scorpius
- Designations
- Theta Scorpii, θ Sco, HR 6553, HD 159532, HIP 86228
- Magnitude
- 1.9
- Position
- RA 17h 37.3m, Dec −42° 60′ (J2000)
- Spectral type
- F1III
- Colour
- yellow-white (B−V 0.44)
- Distance
- 300 light-years
- Discovered
- Known since antiquity
Open AstroPilot to see when Sargas (Theta Scorpii) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view.