MF). As mentioned in @Indebetouw2008, Eq. \[eq3\] was calibrated for large extragalactic sources. It may be valid for the full star-forming regions such as N159, but the SFR calibration may not be accurate when applied to some of our resolved ISM elements, namely those not properly covering the stellar IMF.\
We show the SFR map of the region in units of [$M_\odot$]{} yr$^{-1}$ kpc$^{-2}$ (log scale) in Fig. \[ModelResults\] (lower middle panel). We find a median SFR of 0.06 [$M_\odot$]{} yr$^{-1}$ kpc$^{-2}$ across our modeled region. This average increases to 0.17 [$M_\odot$]{} yr$^{-1}$ kpc$^{-2}$ when we restrict the calculation for resolved ISM elements that have a 3-$\sigma$ detection in the SPIRE bands. This is consistent with the average SFR obtained by @Indebetouw2008 using the H$_2$ surface densities and the Schmitt-Kennicutt law (0.14 [$M_\odot$]{} yr$^{-1}$ kpc$^{-2}$ for N159/N160 and 0.11 [$M_\odot$]{} yr$^{-1}$ kpc$^{-2}$ for the southern molecular ridge to whom the complex belongs to). They find that their SFR estimate for N159/N160 corresponds to that derived using the @Calzetti2007 formula (i.e. a calibration from H$\alpha$ and 24 [$\mu$m]{} luminosities) within uncertainties. We note that the SFR we derive varies significantly across the region. Peaks of SFR correspond to our three star-forming regions, with the N160 centre showing the highest star formation rate of the complex. We indicate the N159S region by a white cross in Fig. \[ModelResults\] (SFR panel). The region does not show massive on-going star formation.

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   ![image](SPIRE_color_dependence){width="18cm"}
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   ![image](SPIRE_color_color_diagram){width="13cm"}
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Submillimeter colours
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@Bendo2011 studied [[*Herschel*]{}]{} colours (i.e. PACS or SPIRE surface brightness ratios) in three nearby g