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Conference Papers Year : 2001

ISOCAM 3-12 microns Imaging of Five Galactic Compact HII Regions

Annie Zavagno


ISOCAM 3-12 microns imaging of five Galactic compact HII regions reveals the spatial distribution of the unidentified infrared band (UIB) emission and underlying continua. The derived UIB intensities (continuum subtracted) agree well with those found from previous works. The distribution of the UIB emission is similar in the five regions: the UIB emission peaks just outside the ionisation front, in the photodissociation region (PDR). Moreover, in four of the five sources for which data exist, the UIB emission zones correlates well with those of 2.12 micron H_2 emission due to fluorescence. UIB emission seems to be related to the molecular and/or atomic hydrogen but this link remains unclear. The 12 micron CVF emission observed with ISOCAM shows a peak near the exciting star in high excitation regions. This indicates that the very small grains, responsible for the strong rising continuum observed in compact HII regions, are located near the star. The (LW6/LW9) ratio obtained using ISOGAL images confirms this result. This ratio can be used as an indicator of the relative importance of the UIB carriers to the very small grains. The high (LW6/LW9) value (2-3) observed in the PDR confirms that the UIB carriers are concentrated there. The perspectives using FIRST are presented.
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hal-03562782 , version 1 (09-02-2022)


  • HAL Id : hal-03562782 , version 1


Annie Zavagno. ISOCAM 3-12 microns Imaging of Five Galactic Compact HII Regions. The Promise of the Herschel Space Observatory, 2000, Toledo, Spain. pp.527. ⟨hal-03562782⟩
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