SIMBAD references

CO and dust emission at millimeter wavelengths are independent tracers of cold interstellar matter, which have seldom been compared on the scale of giant molecular clouds (GMCs) in other galaxies. In this study, and for the first time for the Large Magellanic Cloud (LMC), we compute the molecular cloud masses from the millimeter emission of the dust and compare them with the masses derived from their CO luminosity and virial theorem. We present CO (J=1-0 and J=2-1) and 1.2 mm continuum observations of the N11 star-forming region in the LMC obtained with the SEST telescope and the SIMBA bolometer, respectively. We use the CO data to identify individual molecular clouds and measure their physical properties (CO luminosity, size, line width, and virial masses). The correlations between the properties of the N11 clouds agree with those found in earlier studies in the LMC that sample a larger set of clouds and a wider range of cloud masses. For the N11 molecular clouds, we compare the masses estimated from the CO luminosity (X_COL_CO), the virial theorem (M_vir) and the millimeter dust luminosity (L_1.2mm(dust)). The measured ratios L_CO/M_vir and L_1.2mm(dust)/M_vir constrain the X_CO and K_dust (dust emissivity at 1.2mm per unit gas mass) parameters as a function of the virial parameter α_vir. The comparison between the different mass estimates yields a X_CO-factor of 8.8±3.5x10²⁰cm^–2(K.km/s)^–1α_vir^–1 and a K_dust parameter of 1.5±0.5x10^–3cm2/gα_vir. We compare our N11 results with a similar analysis for molecular clouds in the Gould Belt in the solar neighborhood. We do not find a large discrepancy in N11 between the dust millimeter and virial masses as reported in earlier studies of molecular clouds in the Small Magellanic Cloud. The ratio between L_1.2mm and M_vir in N11 is half of what is measured for Gould Belt clouds, which can be accounted for by a factor of two lower gas-to-dust mass ratio, as the difference in gas metallicities. If the two samples have similar α_vir values, this result implies that their dust far-IR properties are also similar.