Lambda Geminorum

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Lambda Geminorum (λ Gem) is a bright star in the constellation Gemini that you can see with the naked eye at magnitude 3.57. It lies about 101 light-years away and is slowly drifting closer at about 7.4 km/s. The system is likely multiple: the bright primary (component A) is a binary and has a faint companion nearby, with another distant companion detected in observations. The primary star is an A-type star, usually labeled A3V (a hot, hydrogen-burning main-sequence star), though some sources list it as A4IV, indicating it may be slightly more evolved. It spins very fast, with a projected rotation speed around 154 km/s. It has about 2.1 solar masses, about 2.8 solar radii, and shines roughly 27 times brighter than the Sun, with an effective temperature near 7,932 K. The star is relatively young—less than a billion years old. There is infrared light from a dust disk around the star, extending from about 0.08–0.14 AU up to around 0.65 AU. It is also known as 54 Geminorum.