2003A&A...408..493B

We present observations of the dwarf irregular galaxy NGC 4449 at 850µm and 450µm obtained with SCUBA at the JCMT. The distribution of the cold dust agrees well with that of the CO and Hα emission. To explain the integrated mm- through far-infrared continuum spectrum three dust components are required, with temperatures of 16K, 39K and 168K, respectively. The dust mass is dominated by the cold dust component; we derive a total dust mass of ∼3.8x10⁶M_☉, and with the local gas-to-dust ratio of ∼130 a total gas mass of M_HI+H2∼4.9x10⁸M_☉. Comparison with the HI mass leads to a total molecular gas mass of ∼3.4x10⁸M_☉. We derive a conversion factor of the CO line intensity to molecular hydrogen column density X_CO=N_H2/I_CO which is at least 11 times larger than the Galactic value. These values are in accord with the lower metallicity of NGC 4449.