Tau Sagittarii
Tau Sagittarii is a star in the southern zodiac constellation of Sagittarius.Description
With an apparent visual magnitude of +3.3, this is one of the brighter members of the constellation. The distance of this star from Earth is roughly, based upon parallax measurements.
This is a spectral type K1 giant star with about. The stellar envelope is slightly cooler than the Sun with an effective temperature of 4,459 K, giving the star a light orange color. The interferometry-measured angular diameter of this star, after correcting for limb darkening, is, which, at its estimated distance, equates to a physical radius of about 16 times the radius of the Sun.
τ Sagittarii is a suspected double star although no companion has been confirmed yet. A lower metal content and a high peculiar velocity relative to the Sun suggest the star is a visitor from a different part of the Galaxy.
τ Sagittarii is a red clump giant, a star with similar mass to the sun which has exhausted its core hydrogen, passed through the red giant branch, and started helium fusion in its core.τ Sagittarii is the closest constellational star to the origin of the 1977 Wow! signal.Name and etymology
- The star forms part of simple asterisms:
- * γ Sgr, τ Sgr, δ Sgr, ε Sgr, ζ Sgr, λ Sgr, σ Sgr and φ Sgr — the Teapot.
- * φ Sgr, τ Sgr, ζ Sgr, χ Sgr and σ Sgr — the Returning Ostriches; in Arabic Al Naʽām al Ṣādirah often transliterated as Namalsadirah.
- ** Originally four stars in a numerical order: φ Sgr, τ Sgr, χ1 Sgr and χ2 Sgr
- * ν Sgr, τ Sgr, ψ Sgr, ω Sgr, 60 Sgr and ζ Sgr, Al Udḥiyy — the Ostrich's Nest.
- * In the entirely separate Chinese tradition — 斗, meaning Dipper: τ Sgr, φ Sgr, λ Sgr, μ Sgr, σ Sgr and ζ Sgr. The star itself is 斗宿五.
