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Astron. Astrophys. 315, L381-L384 (1996)

Mid-Infrared spectrum of the zodiacal light*

W.T. Reach1, A. Abergel1, F. Boulanger1, F.-X. Désert1, M. Perault4, J.-P. Bernard1, J. Blommaert3, C. Cesarsky2, D. Cesarsky1, L. Metcalfe3, J.-L. Puget1, F. Sibille5, and L. Vigroux2

1 Institut d'Astrophysique Spatiale, Bât. 121, Université Paris XI, F-91405 Orsay Cedex, France
2 Service d'Astrophysique, Centre d'Etudes de Saclay, F-91191 Gif-sur-Yvette Cedex, France
3 ISO Science Operations Centre, Astrophysics Division of ESA, Villafranca, Spain
4 Ecole Normale Supérieure, Paris, France
5 Observatoire de Lyon, Lyon, France

Received 16 July 1996 / Accepted 23 August 1996

Abstract. Using the mid-infrared camera on the Infrared Space Observatory (ISO), the spectrum of a relatively empty piece of sky, dominated by zodiacal light, was measured from 5 to 16.5 img1.gifm wavelength. The spectrum has no spectral features brighter than 15% of a blackbody fit to entire spectrum; the temperature of the fit is img2.gif K. No galactic or cosmic background spectral features are detected. Comparison to models for three size distributions of spherical grains composed of several different materials reveals acceptable fits only for `astronomical silicate,' ruling out graphite, magnetite, andesite, obsidian, glassy carbon, or water ice as the constituent of material producing the zodiacal emission. The size distribution is constrained to have relatively fewer small particles compared to the coma of P/Halley. There is a hint of a 9-11 img1.gifm feature, which suggests that the particles producing the zodiacal light are composed of silicates similar to those found in the coma of P/Halley, collected interplanetary dust particles, and the dust around the nearby star img3.gif Pic.

Key words: interplanetary dust - background radiation - zodiacal light

* Based on observations with the Infrared Space Observatory (ISO). ISO is 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.

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