constant, τ {\displaystyle \tau } , relates to the decay rate constant, λ, in the following way: τ = 1 λ . {\displaystyle \tau ={\frac {1}{\lambda }}.} The
Lambda Tauri (λTau, λ Tauri) is a triple star system in the constellation Taurus. In the Calendarium of Al Achsasi Al Mouakket, this star was designated