Physical studies of Centaurs and Trans-Neptunian Objects with the Atacama Large Millimeter Array

Once completed, the Atacama Large Millimeter Array (ALMA) will be the most powerful (sub)millimeter interferometer in terms of sensitivity, spatial resolution and imaging. This paper presents the capabilities of ALMA applied to the observation of Centaurs and Trans-Neptunian Objects, and their possible output in terms of physical properties. Realistic simulations were performed to explore the performances of the different frequency bands and array configurations, and several projects are detailed along with their feasibility, their limitations and their possible targets. Determination of diameters and albedos via the radiometric method appears to be possible on ∼500 objects, while sampling of the thermal lightcurve to derive the bodies’ ellipticity could be performed at least 30 bodies that display a significant optical lightcurve. On a limited number of objects, the spatial resolution allows for direct measurement of the size or even surface mapping with a resolution down to 13 milliarcsec. Finally, ALMA could separate members of multiple systems with a separation power comparable to that of the HST. The overall performance of ALMA will make it an invaluable instrument to explore the outer Solar System, complementary to space-based telescopes and spacecrafts.

► This paper explores the capabilities of the Atacama Large Millimeter Array applied to the observation of Centaurs and Trans-Neptunian Objects.
► More than 500 objects can be thermally detected in bands 6 or 7, allowing determination of sizes and albedo through the radiometric method.
► Using extended configurations to spatially resolve the targets, model-independent size and ellipticity measurements could be obtained on 30 large bodies.
► The first thermal maps of the 6 largest Centaurs and TNOs could be obtained with a spatial resolution down to ∼14 mas.