Astron. Astrophys. 320, 594-604 (1997)

5. Conclusions

We presented near infrared broad band and narrow band images of the S 235 A-B star forming region. Their analysis, together with new molecular data brings to the following new picture of the complex:

1. The presence of an embedded stellar cluster in the S 235 A-B region is confirmed. The center of the cluster appears to be located between the two nebulosities, where the molecular core and the youngest cluster members are located.
2. Br emission occurs mainly in the vincinity of S 235 A and B, and hot molecular hydrogen is distributed around S 235 A, especially in a belt-like region of the south it, at the interface between the HII region and the molecular core. The morphology of the emission confirms that S 235 A and B are (moderately) evolved YSOs, that are emerging from the parental cloud.
3. The driving source of the H₂ O maser has been identified on the near infrared images. On the basis of the infrared results and the C³⁴ S, ¹³ CO molecular lines observations, the newly discovered NIR object M1 is suggested to be the powering source of the H₂ O maser. This object, which does not coincide with any detected radio continuum source, appears to be one of the youngest in the region and to be located in the innermost part of the cloud core, at the center of a stellar cluster. These characteristics suggest that the source is probably the first manifestation of a massive YSO, a precursor of the UCHII phase.
4. A large fraction of the mass of the cloud core () has already been converted into young stars.

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998
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