The Small Magellanic Cloud in the far infrared^*

II. Global properties

¹ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
² Helsinki University Observatory, Tähtitorninmäki, PO Box 14, 0014 University of Helsinki, Finland

Corresponding author: U. Klaas, klaas@mpia.de

Received: 24 July 2003
Accepted: 7 October 2003

Abstract

We present global IR properties of the Small Magellanic Cloud using an ISOPHOT 170 μm map and re-visited IRAS data. The integrated 170 μm flux is 14 950 ± 2300 Jy, and the integrated IR flux is  W m^-2. Discrete sources contribute 28%, 29%, and 36% to the integrated flux at 60 μm, 100 μm, and 170 μm, respectively. Most of the total emission arises from diffuse emission regions surrounding the HII regions. The SED can be modelled by the composition of a 45 K, a 20.5 K and a 10 K blackbody component with emissivity index . A color temperature map is constructed from the ISOPHOT 170 μm and the IRAS 100 μm HiRes maps. The average dust temperature is  K. The total dust mass is found to be , yielding a gas-to-dust mass ratio M_gas/, a value 25 times lower than found by former studies. The global star formation rate is estimated to SFR yr^-1. The comparison with other irregular galaxies reveals the SMC as quiet with no peculiar FIR properties.