Star formation in the S233 region

The main objective of this paper is to study the possibility o f triggered star formation on the border of the H II region S233, which is formed by a B-star. Using high-resolution spectra we determine the spectral class of the ionizing star as B0.5 V and the radial velocity of the star to be 17.5±1.4 km s 1 . This value is consistent with the velocity of gas in a wide fie ld across the S233 region, suggesting that the ionizing star was formed from a parent cloud belonging to the S233 region. By studying spatial-kinematic structure of the molecular cloud in the S233 region, we detected an isolated clump of gas producing CO emission red-shifted relative to the parent cloud. In the UKIDSS and WISE images, the clump of gas coincides with the infrared source containing a compact object and bright-rimmed structure. The bright-rimmed structure is perpendicular to the direction of the ionizing star. The compact source coincides in position with IRAS source 05351+3549. All these features indicate a possibility of triggering formation of a next-generation star in the S233 region. Within the framework of a theoretical one-dimensional model we conclude that the ‘collect-and-collapse’ process is not likely to take place in the S233 region. The presence of the bright-rimmed structure and the compact infrared source suggest that the ‘collapse of the pre-exist ing clump’ process is taking place.