Observations

The Large Magellanic Cloud has been surveyed in neutral hydrogen emission with the ATCA. The mosaic consists of 1344 separate pointings of the 750-m array (4 configurations) covering a field of with an angular resolution of 60'' ( pc) and a velocity resolution of 1.6 km . The images show the detailed spatial structure of the neutral interstellar gas in the LMC for the first time. Figureá 1 is a close-up of the HI in a 10 square-degree region in the north of the LMC containing the supergiant shells LMCá 4 and 5 (Meaburn 1980). Figureá 2 is an HI image of the whole LMC. Both figures are peak-brightness-temperature images. On small-to-medium scales, the combined action of numerous shells and supershells dominates the structures and motions of the HI in the LMC. On large scales, the LMC is remarkably symmetric in appearance compared with at other wavelengths and shows a pronounced spiral pattern. A southern spiral arm is seen for the first time. This arm extends out from the `B3' stub tentatively identified by de Vaucouleurs and Freeman (1972).

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Figure 1: á The peak HI brightness temperature around the supergiant shells, LMCá 4 and 5 (see Meaburn 1980). The newly found supershell next to the LMC 5 has a diameter of about 1.4 kpc.

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Figure 2: á The peak HI brightness temperature image from the ATCA survey of the LMC. On the largest scales, the LMC shows remarkable symmetry in its structure compared with at other wavelengths. On smaller scales, the affect of numerous wind and supernova-blown shells is apparent. The highest brightness temperature in this image is 109 K.

á© Copyright Astronomical Society of Australia 1997