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Astron. Astrophys. 315, L309-L312 (1996)

Infrared spectrophotometry of M 17 with ISOCAM

D. Cesarsky1, J. Lequeux2, A. Abergel1, M. Perault1, E. Palazzi3, S. Madden4, and D. Tran4

1 Institut d'Astrophysique Spatiale, Bat. 121, Université Paris XI, F-91450 Orsay Cedex, France
2 Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris, France
3 Istituto TESRE/CNR, via Gobetti 101, I-40129 Bologna, Italy,
4 SAp/DAPNIA/DSM, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex, France

Received 16 July 1996 / Accepted 20 August 1996

Abstract. We report spectrophotometric observations of the HII  region/neutral medium interface in M17  obtained with the ISOCAM Circular Variable Filter (CVF) in the spectral range 5.15 to 16.5 img2.gifm. The lines of singly-ionized species come mainly from the clumpy "neutral" interface, while the HII  region dominates the line emission by higher-ionization species. The emission in the Unidentified Infrared Bands (UIBs) comes from the molecular cloud and the interface and extends into the HII  region. In the regions where the radiation field is larger than about img3.gif times the standard interstellar one, the continuum is dominated by the emission of very small grains which are bigger than those responsible for the UIBs.

Key words: ISM: M17  - ISM: dust - ISM: molecules - ISM: atoms - infrared: ISM: lines and bands - infrared: ISM: continuum

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Last change: December 16, 1996
© European Southern Observatory (ESO) 1996