Katsuo Ogura
Kokugakuin University, Higashi, Shibuya-ku, Tokyo 150-8440,
Japan
Abstract. Star formation associated with H II regions is briefly reviewed. Special emphasis is laid on our series of observational studies on bright-rimmed clouds (BRCs), in which we found a phenomenon called "small-scale sequential star formation." In addition a new hypothesis is advocated on the two modes of star formation associated with H II regions, i.e., the cluster and dispersed modes. The former gives birth to a rich cluster and in the associated H II region BRCs are formed only at a later stage of its evolution in the peripheries. In the latter mode no clusters or only loose ones are formed, but BRCs can appear at earlier stages in inner part of the H II region. Presumably these modes depend on the initial density distribution of the natal molecular cloud.
Keywords: H II regions ISM: globules stars: formation OB associations