... era

Based on observations with the Infrared Space Observatory (ISO), an ESA project with instruments funded by ESA member States (especially the PI countries: France, Germany, The Netherlands, and the UK) and with the participation of ISAS and NASA.

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...

Table 2 and Appendices A and B are only available in electronic form at http://www.edpsciences.org

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... normal

By "normal'' we loosely refer to galaxies which are not dominated by an active nucleus and whose current star formation rates would be sustainable for a substantial fraction of a Hubble time.

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... factors

These correction factors are the multiplicative factors by which the total FIR luminosity (40-1000 ${ \mu }$m), as derived from ISO measurements, differs from the IRAS FIR luminosity, derived from the formula (Helou et al. 1988): $f_{40-120}[{\rm W~m^{-2}}]=1.26\times 10^{-14}~(2.58f_{60~{\rm\mu m}}+f_{100~{\rm\mu m}})$, with $f_{60~{\rm\mu m}}$ and $f_{100~{\rm\mu m}}$ expressed in Jy.

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... regions

In the context of dust emission we use the term HII regions to denote not only the optical emitting HII regions within the star forming complexes, but also their immediate vicinity where grains can also be strongly heated by the massive stars.

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...${ \mu }$m

A subsample of the ISOPHOT Virgo Cluster Deep Sample has been also observed with the Long Wavelength Spectrometer at the 158 $\rm\mu m$ [CII] fine-structure gas cooling line (Leech et al. 1999) and analysed by Pierini and collaborators (1999, 2001, 2003).

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... expressed

The formulation in Eq. (2) is applicable for the case that the diffuse component is illuminated by a continuous stellar emissivity, and neglects the discrete character of stars.

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... content

Broadly speaking, the dust content is proportional to the metal abundance (e.g. [O/H]) times the average gas column density of the disk. [O/H] is known to increase with the optical luminosity of the galaxy (Zaritsky et al. 1994), enforcing the idea that the metal content of a galaxy like our own is mostly the result of the past star formation activity (e.g. Dwek 1998). In absence of an observationally established relation between metallicity of the disk and SFR, we expect this metallicity to contribute only to the scatter of the relation between dust content and SFR.

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... IRAF

IRAF is the Image Analysis and Reduction Facility made available to the astronomical community by the National Optical Astronomy Observatories, which are operated by AURA, Inc., under contract with the US National Science Foundation.

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