Lambda Sagittarii
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| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 27m 58.2s |
| Declination | -25° 25' 18" |
| Apparent magnitude (V) | +2.82 |
| Distance | 77.3 ± 1.6 ly (23.7 ± 0.5 pc) |
| Spectral type | K1+IIIb |
| Other designations | |
Lambda Sagittarii (λ Sgr / λ Sagittarii) is a star within the constellation Sagittarius. The star marks the top of the Archer's bow. It also has the traditional name Kaus Borealis.
The traditional name is derived from "bow" (qaws Arabic) + "northern" (borealis Latin). Below it lie the other stars of the bow, Kaus Media and Kaus Australis. Kaus Borealis also marks the top of the lid of the so-called "Teapot" asterism.
Kaus Borealis is a spectral class K orange giant star. It is currently fusing helium into carbon and oxygen in its core. Kaus Borealis is 77 light years from us, with a mass 2.3 times that of the Sun It is 52 times more luminous than the Sun and has a radius of some 11 Suns.
Being near the ecliptic, Lambda Sgr is sometimes occulted by the Moon and , more rarely by a planet. The last planet to pass in front of it was Venus, on 19 November 1984. The previous occasion was on 5 December 1865, when it was occulted by the planet Mercury.
