The multiphase medium in the interstellar complex N44

We have obtained high-resolution H I observations of N44, one of the larges t H II complexes in the Large Magellanic Cloud. The distribution and intern al motions of the H I gas show dynamic effects of fast stellar winds and su pernova blasts. Numerous H I holes are detected, with the most prominent tw o corresponding to the optically identified superbubbles Shell 1 and Shell 2. The H I gas associated with Shell 1 shows an expansion pattern similar t o that of the ionized gas shell, but the mass and kinetic energy of the H I shell are 3-7 times those of the ionized gas shell. The total kinetic ener gy of the neutral and ionized gas of Shell 1 is still more than a factor of 5 lower than expected in a pressure-driven superbubble. It is possible tha t the central OB association was formed in a molecular cloud and a visible superbubble was not fully developed until the ambient molecular gas had bee n dissociated and cleared away. This hypothesis is supported by the existen ce of a molecular cloud toward N44 and the fact that the apparent dynamic a ge of the superbubble Shell 1 is much shorter than the age of its OB associ ation LH 47. Accelerated H I gas is detected at SNR 0523-679. The mass and kinetic energy in the associated H I gas are also much higher than those in the ionized gas of SNR 0523-679. Studies of interstellar gas dynamics usin g ionized gas alone are clearly inadequate; neutral gas components must be included.