Gomez’s Hamburger (IRAS 18059-3211): A pre main-sequence A-type star

Aims. We aim to study the nature of Gomez’s Hamburger (IRAS 18059-3211; GoHam), a nebula that has been proposed to be a post-AGB object. Such a classification is not confirmed, instead we argue that it will be a key object in the study of disks rotating around young stars. Methods. We present high resolution SMA maps of CO J=2–1 in Gomez’s Hamburger. The data are analyzed by means of a code that simulates the emission of a nebula showing a variety of physical conditions and kinematics. Results. Our observations clearly show that the CO emitting gas in Gomez’s Hamburger forms a spectacular disk in keplerian rotation. Model calculations undoubtly confirm this result. The central (mainly stellar) mass is found to be high, ∼ 4 M for a distance of 500 pc. The mass and (relatively low) luminosity of the source are, independently of the assumed distance, very different from those possible in evolved stars. GoHam is probably a transitional object between the pre-MS and MS phases, still showing interstellar material around the central star or stellar system.