H i observations of three compact high-velocity clouds around the Milky Way

Abstract

Context. We present deep H i observations of three compact high-velocity clouds (CHVCs). Aims. The main goal is to study their diffuse warm gas and compact cold cores. We use both low-and high-resolution data obtained with the 100 m Effelsberg telescope and the Westerbork Synthesis Radio Telescope (WSRT). The combination is essential in order to study the morphological properties of the clouds since the single-dish telescope lacks a sufficient angular resolution while the interferometer misses a large portion of the diffuse gas. Methods. Here single-dish and interferometer data are combined in the image domain with a new combination pipeline. The combination makes it possible to examine interactions between the clouds and their surrounding environment in great detail. Results. The apparent difference between single-dish and radio interferometer total flux densities shows that the CHVCs contain a considerable amount of diffuse gas with low brightness temperatures. A Gaussian decomposition indicates that the clouds consist predominantly of warm gas. © 2014 ESO.