Lambda Scorpii
A bright triple star system in the tail of Scorpius.
Lambda Scorpii, also known by its formal name Shaula, is a triple star system that ranks as the second-brightest object in the constellation Scorpius. Its apparent visual magnitude of 1.63 places it among the night sky’s brightest stars. The Bayer designation Lambda Scorpii is a Latinized form of λ Scorpii.
The traditional name Shaula comes from the Arabic *al-šawlā’*, meaning "the raised [tail]," reflecting its position in the scorpion’s tail. In 2016, the International Astronomical Union’s Working Group on Star Names approved Shaula for the component λ Scorpii Aa1. In Indian astronomy, it belongs to the asterism Mula, the 19th nakshatra in Vedic astrology, symbolized by a bundle of roots or an elephant goad. In Chinese astronomy, it is part of the Tail asterism, which includes several other Scorpius stars; λ Scorpii itself is known as "the Eighth Star of Tail." Babylonian records list Shaula together with υ Scorpii (Lesath) as *dSharur4 u dShargaz*, meaning "Sharur and Shargaz," while in Coptic the pair was called Minamref. The Boorong people of northwestern Victoria, Australia, named the two stars Karik Karik, "the Falcons."
The system lies about 570 light-years from the Sun. Spectroscopic and interferometric observations reveal three stars: two B-type stars and a pre-main-sequence star. The primary is a Beta Cephei variable, showing rapid brightness changes of roughly a hundredth of a magnitude. The pre-main-sequence star orbits every 6 days, and the B-type companion every 1,053 days. All three share the same orbital plane, suggesting they formed together. Their masses are 14.5, 2.0, and 10.6 solar masses, respectively, and the system is estimated to be 10–13 million years old. The primary, Shaula Aa1, is massive enough to eventually explode as a supernova.
Two fainter stars lie nearby: a 15th-magnitude star 42 arcseconds away and a 12th-magnitude star 95 arcseconds away. Whether they are physically associated is uncertain. If they are, the projected separations would be about 7,500 and 17,000 astronomical units (0.27 light-years), respectively. Gaia Data Release 3 indicates the fainter star is slightly larger and brighter than the Sun and about 420 light-years away, while the brighter star is a background object.
Shaula appears on the flag of Brazil, representing the state of Rio Grande do Norte. The U.S.
- Apparent magnitude
- 1.63
- Distance
- approximately 570 light-years
- Spectral type
- B-type (primary and companion)
- Mass (primary)
- 14.5 solar masses
- Mass (pre-main-sequence star)
- 2.0 solar masses
- Mass (b-type companion)
- 10.6 solar masses
- Age
- 10–13 million years
Lore & Background
Lambda Scorpii bears the traditional name Shaula, from the Arabic al-šawlā´ meaning 'the raised [tail]', as it lies in the tail of Scorpius. In 2016, the International Astronomical Union's Working Group on Star Names approved Shaula for the star λ Scorpii Aa1. In Indian astronomy, it is part of the asterism Mula, the 19th nakshatra in Vedic astrology, whose symbol is a bunch of roots tied together or an elephant goad. In Chinese astronomy, it is the Eighth Star of Tail, an asterism comprising eleven stars in Scorpius. Together with υ Scorpii (Lesath), Shaula appears in the Babylonian compendium MUL.APIN as dSharur4 u dShargaz, meaning 'Sharur and Shargaz'; in Coptic these two stars were called Minamref. The indigenous Boorong people of northwestern Victoria (Australia) named them Karik Karik, 'the Falcons'.
Reader's Guide
Lambda Scorpii is notable as a triple star system whose components all lie in the same orbital plane, suggesting they formed together. The primary is a Beta Cephei variable star with rapid brightness changes of about a hundredth of a magnitude. Spectroscopic and interferometric observations have revealed two B-type stars and a pre-main-sequence star, with orbital periods of 6 days and 1,053 days. The primary has sufficient mass to explode as a supernova. Two fainter stars lie at separations of 42 and 95 arcseconds; Gaia Data Release 3 reports that the fainter of these is a little larger and brighter than the Sun and about 420 light-years away, while the brighter star is a background object. Shaula appears on the flag of Brazil, symbolizing the state of Rio Grande do Norte. The U.S. Navy named a Crater-class cargo ship USS Shaula (AK-118) after the star, and Shaula is the namesake of a character in the Japanese web/light novel series Re:Zero by Tappei Nagatsuki.
Did You Know?
- Lambda Scorpii is the second-brightest object in the constellation of Scorpius.
- The system contains a pre-main-sequence star with an orbital period of 6 days.
- The primary star has enough mass to explode as a supernova.
Frequently Asked Questions
What is Lambda Scorpii (Shaula)?
Lambda Scorpii, commonly called Shaula, is a triple star system situated in the tail region of the constellation Scorpius. It holds the distinction of being the second-brightest star visible within that constellation.
Where does the name Shaula come from?
The name derives from the Arabic phrase al-šawlā', which translates to 'the raised [tail],' a nod to its position in the scorpion's tail. The IAU formally approved 'Shaula' as the proper name for the primary component in 2016.
How bright is Lambda Scorpii in the night sky?
With an apparent visual magnitude of 1.63, it ranks among the brightest stars visible to the naked eye. This level of brightness is what secures its place as the second-most luminous object in Scorpius.
What stars make up the Lambda Scorpii system?
The system consists of three components: a 14.5-solar-mass B-type primary, a 10.6-solar-mass B-type companion, and a 2.0-solar-mass pre-main-sequence star. All three orbit together at a distance of roughly 570 light-years from Earth.
How far is Lambda Scorpii from Earth?
The triple system sits at an approximate distance of 570 light-years from our solar system. Despite that range, its combined light still registers at magnitude 1.63, making it readily visible from dark-sky locations.
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