We study the far-infrared emission properties of the nearby starburst galaxy NGC 253 based on IRAS maps and an ISOPHOT map at 180 \mu m. Based on the analysis of the light profiles , we have been able to identify three main structural components : an unresolved nuclear component , an exponential disk , and a kiloparsec scale bar .
In addition , we also found a ring structure at the end of the bar that is particularly conspicuous at 12µm .
The Spectral Energy Distribution ( SED ) of each morphological component has been modeled as thermal dust emission at different temperatures .
The unresolved nuclear component is dominated by cold dust emission ( T _ { n } \simeq 50 K ) , whereas the disk emission is dominated by very cold dust ( T _ { vc } ^ { d } \simeq 16 K ) plus a contribution from cold dust ( T _ { c } ^ { d } \simeq 55 K ) .
The bar emission corresponds mainly to cold dust ( T _ { c } ^ { b } \simeq 23 K ) plus a warm component ( T _ { w } ^ { b } \simeq 148 K ) .
We detect an extension of the disk emission due to very cold dust , which contributes a large fraction ( 94 % ) of the total dust mass of the galaxy .
The estimated total dust mass is 8.2 \times 10 ^ { 7 } M _ { \odot } .