Disc structure and properties in Herbig AeBe stars

The extensive information on the structure of the disk structure of Herbig stars and its various properties have been presented. HBe stars, which continue to be covered by molecular cloud remnant materials, evolve more rapidly towards the Main Sequence. The fact that the bulk of the mass is located in the optically thick midplane during the crystallization of dust particles and the decrease in the radiation surface per unit mass as the particles grow can be considered as one of the main facts why the various evolutionary stages of protoplanetary disks remain unstudied.