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Astron. Astrophys. 364, 723-731 (2000)

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Extended red emission and unidentified infrared bands in the galactic compact H II region Sh 152 *

S. Darbon 1, A. Zavagno 2, J.-M. Perrin 1, C. Savine 1, V. Ducci 2 and J.-P. Sivan 1

1 Observatoire de Haute Provence du CNRS, 04870 Saint Michel l'Observatoire, France
2 Observatoire de Marseille, 2 Place Le Verrier, 13248 Marseille Cedex 4, France

Received 22 November 1999 / Accepted 28 September 2000


We present visible and infrared images and low-dispersion visible spectra of the galactic compact HII region Sh 152. The spatial distribution of the Extended Red Emission (ERE) over the nebula is found to coincide with that of the ionized hydrogen emission and to differ from that of the Unidentified InfraRed Bands (UIRBs) emission at 3.3 and 6.2 µm. This result and other considerations are in favour of grains as carriers of the ERE. It is shown that nanosized silicon particles could account for the ERE in terms of luminescence, an interpretation which, however, suffers from some limitations.

Key words: scattering – ISM: individual objects: Sh 138 – ISM: dust, extinction – ISM: H ii regions – infrared: ISM: lines and bands

* Partly based on observations made at Observatoire de Haute Provence du CNRS (France) and with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

Send offprint requests to: J.-P. Sivan

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001