Star formation in the S233 region

• Published in: arXiv.org 2015-06
• Main Authors: Ladeyschikov, D A, Sobolev, A M, S Yu Parfenov, Alexeeva, S A, Bieging, J H
• Format: Article
• Language: English
• Subjects: Collapse; Molecular clouds; Molecular structure; One dimensional models; Radial velocity; Spectral classification; Star & galaxy formation; Star formation
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1506.05888

The main objective of this paper is to study the possibility of triggered star formation on the border of the HII 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. This value is consistent with the velocity of gas in a wide field 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-existing clump" process is taking place.