Sh2-205. I, the surrounding interstellar medium

G. A. Romero, C. E. Cappa.

15 págs. : ilustraciones

Serie: Trabajos publicados del IAR ; no. 817

Resumen: We present a study of the HII region Sh2-205 and its environs, based on data obtained from the CGPS, 12CO observations, and MSX data. We find that Sh2-205 can be separated in three independent optical structures: SH149.25—0.0, SH 148.83-0.67, and LBN 148.11-0.45. The derived spectral indices show the thermal nature of SH 148.83—0.67 and LBN 148.11—0.45. The morphology of SH 148.83—0.67, both in the optical and radio data, along with the energetic requ irements indicate that this feature is an interstellar bubble powered by the UV photons of HD 24431 (O9 III). LBN 148.11—0.45 has the morphology of a classic al HII region and their ionizing sources remain uncertain. Dust and molecular gas are found related to LBN 148.11-0.45.Particularly, a photodissociation region is detected at the interface between the ionized and molecular regions. If the proposed exciting star HD 24094 were an O8—O9 type star, as suggested by its near-infrared colors, its UV photon flux would be enough to explain the ionization of the nebula.