Delta Geminorum
Delta Geminorum (δ Gem, δ Geminorum) is a star in the constellation Gemini. It has the traditional name Wasat, which comes from the Arabic word for "middle".
It has an apparent visual magnitude of +3.53, allowing it to be seen with the naked eye. Wasat is only two-tenths of a degree south of the ecliptic, and therefore is occasionally occulted by the Moon and, more rarely, by a planet. The last occultation by a planet was by Saturn on June 30, 1857, and the next will be by Venus on August 12, 2420. In 1930, the dwarf planet Pluto was discovered about 0.5° to the east of this star by American astronomer Clyde Tombaugh.
In Chinese, 天樽 (Tiān Zūn), meaning Celestial Wine Cup, refers to an asterism consisting of δ Geminorum, 57 Geminorum and ω Geminorum. Consequently, δ Geminorum itself is known as 天樽二 (Tiān Zūn èr, English: the Second Star of Celestial Wine Cup.). From this Chinese name, the name Ta Tsun has appeared.
Properties
Delta Geminorum is a subgiant star with the stellar classification F0 IV. It is about 60.5 light-years (18.5 parsecs) distant. This star has 1.57 times the mass of the Sun and is rotating rapidly with a projected rotational velocity of 129.7 km s−1. The estimated age is 1.6 billion years.
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