Mid-infrared spectrum of the zodiacal light observed with ISOPHOT^*

¹ Max–Planck–Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
² Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary
³ Instituto de Astrofísica de Canarias, via Láctea s/n, 38200 La Laguna, Tenerife, Spain
⁴ European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching b. München, Germany

Corresponding author: Ch. Leinert, leinert@mpia-hd.mpg.de

Received: 2 September 2001
Accepted: 11 July 2002

Abstract

We present 29 mid-infrared spectra of the zodiacal light distributed over the sky. The observed 5.9–11.7 μm spectral shapes are well represented by blackbody radiation with colour temperatures in the range of  K. The spectra are smooth and featureless. The variation of the temperature can be explained by the geometrical distribution of dust in the inner solar system. This result indicates that although the interplanetary dust particles originate from discrete sources (comets, asteroids) the interplanetary cloud of today seems to be well mixed in terms of grain composition and size distribution.