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ISOGAL Observations of Giant Molecular clouds: The S152/3 Complex

E. Copet 1, A. Omont 2, A. Zavagno 3, & ISOGAL Team

1 DESPA - Observatoire de Paris

2 Institut d'Astrophysique de Paris

3 Observatoire de Marseille




ISOGAL is a detailed mid-IR imaging survey of the inner Galaxy and combine ISOCAM 7 and 15 microns observations with I,J and K DENIS data. The main goal of the project is to trace galactic structure and stellar populations, and include the observation of some HII regions. The S152/3 complex is a Sharpless HII region associated with a CO cloud in the Perseus arm. Previous surveys (IRAS) on this region show a strong infrared peak centered on S152 and an extensive 6cm emission not seen in CO. ISOGAL has mapped a area of 20' x 20' at LW6 and LW9 band on this region with a spatial resolution of 6 arcsec., a small image centered on S152 have been observed by Zavagno et al. with a 3 arcsec. pixel size. On this Poster, we present an analysis of the Mid-IR stellar population: we have detected at LW6 (LW9), 250 (120) sources, in the whole area. The analysis of the extensive emission, and the ratio LW6/LW9 (PAH/Continuum) show a clear deficit of LW6 emission close to the ionizing source. Assuming a distance of 3.6 kpc for S152/3 complex and that PAH is responsible for the LW6 emission, this 30 parsec ``hole'' could be due to a PAH destruction by the O9V ionizing star.


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Next: Dust properties in the Up: Poster session C Interstellar Previous: Last ISOCAM results on
"The Universe as seen by ISO", 20 - 23 October 1998, Paris: Abstract Book