Modular orthogonal Yangians

We study the (extended) orthogonal Yangians associated to the Lie algebras types $B$ and $D$ over a field of positive characteristic. We define the $p$-center for the Yangians and obtain an explicit description of the center in terms of Drinfeld generators, showing that the center is generated by its Harish-Chandra center together with a large $p$-center.