Zeros and logarithmic asymptotics of Sobolev orthogonal polynomials for exponential weights

We obtain the (contracted) weak zero asymptotics for orthogonal polynomials with respect to Sobolev inner products with exponential weights in the real semiaxis, of the form xγe−φ(x), with γ>0γ>0, which include as particular cases the counterparts of the so-called Freud (i.e., when φφ has a polynomial growth at infinity) and Erdös (when φφ grows faster than any polynomial at infinity) weights. In addition, the boundness of the distance of the zeros of these Sobolev orthogonal polynomials to the convex hull of the support and, as a consequence, a result on logarithmic asymptotics are derived.