Physical properties of giant molecular clouds in the Large Magellanic Cloud

摘要: The Magellanic Mopra Assessment (MAGMA) is a high angular resolution ^(12)CO (J = 1 → 0) mapping survey of giant molecular clouds (GMCs) in the Large Cloud (LMC) and Small using Telescope. Here we report on basic physical properties 125 GMCs LMC that have been surveyed to date. observed exhibit scaling relations are similar those determined for Galactic GMCs, although narrower linewidths lower CO luminosities than size. average mass surface density 50 M_⊙ pc^(−2), approximately half inner Milky Way. We compare with without signs massive star formation, finding non-star-forming peak brightness star-forming GMCs. estimates local interstellar conditions: specifically, investigate H i column density, radiation field, stellar external pressure. Very few cloud demonstrate clear dependence environment; exceptions significant positive correlations between (i) GMC velocity dispersion, (ii) (iii) brightness. formation shows no which inconsistent photoionization-regulated theory proposed by McKee. find some evidence MAGMA increases pressure, as Elmegreen, but detailed predictions this model not fulfilled once metallicity envelope taken into account.