ON THE POSSIBLE ORIGIN OF LAMBDA-BOO STARS

We discuss a new approach to the problem of the origin of lambda Boo s tars. It is proposed that at least some of these stars may arise from contact binary systems of W UMa type. Simple estimations based on this supposition can account for the present-day number of lambda Boo star s in the solar neighbourhood, their masses and spectral classes. It is also important that the proposed scenario does not exclude circumstel lar shell formation which is responsible for the chemical peculiaritie s of lambda Boo stars.