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This is the first publication of the DEATHSTAR project. The goal of theproject is to reduce the uncertainties of observational estimates of mass-lossrates from Asymptotic Giant Branch (AGB) stars. Line emission from 12CO J=2-1and 3-2 were mapped using the ACA. In this initial analysis, the emissiondistribution was fit to a Gaussian distribution in the uv-plane. Detailedradiative transfer analysis will be presented in the future. The axes of thebest-fit Gaussian at the line center of the 12CO J=2-1 emission gives a firstindication of the size of the emitting region. Furthermore, the fittingresults, such as the major and minor axis, center position, and the goodness offit across both lines, constrain the symmetry of the emission distribution. Wefind that the CO envelope sizes are, in general, larger for C-type than forM-type AGB stars, which is expected if the CO/H2 ratio is larger in C-typestars. Furthermore, a relation between the 12CO J=2-1 size and circumstellardensity is shown that, while in broad agreement with photodissociationcalculations, reveals large scatter and systematic differences between thestellar types. The majority of the sources have CO envelopes that areconsistent with a spherically symmetric, smooth outflow. For about a third ofthe sources, indications of strong asymmetries are found. This is consistentwith previous interferometric investigations of northern sources. Smaller scaleasymmetries are found in a larger fraction of sources. These results for COenvelope radii and shapes can be used to constrain detailed radiative transfermodeling of the same stars so as to determine mass-loss rates that areindependent of photodissociation models. For a large fraction of the sources,observations at higher spatial resolution will be necessary to furtherinvestigate the complex circumstellar dynamics revealed by our ACAobservations.

DEATHSTAR: Nearby AGB stars with the Atacama Compact Array I. CO envelope sizes and asymmetries: A new hope for accurate mass-loss-rate estimates