The Ophiuchus DIsc Survey Employing ALMA (ODISEA) – I: project description and continuum images at 28 au resolution

Abstract

We introduce the Ophiuchus DIsc Survey Employing ALMA (ODISEA), a project\naiming to study the entire population of Spitzer-selected protoplanetary discs\nin the Ophiuchus Molecular Cloud (~300 objects) from both millimeter continuum\nand CO isotopologues data. Here we present 1.3 mm/230 GHz continuum images of\n147 targets at 0.2" (28 au) resolution and a typical rms of 0.15 mJy. We detect\na total of 133 discs, including the individual components of 11 binary systems\nand 1 triple system. Fifty-three of these discs are spatially resolved. We find\nclear substructures (inner cavities, rings, gaps, and/or spiral arms) in 8 of\nthe sources and hints of such structures in another 4 discs. We construct the\ndisc luminosity function for our targets and perform comparisons to other\nregions. A simple conversion between flux and dust mass (adopting standard\nassumptions) indicates that all discs detected at 1.3 mm are massive enough to\nform one or more rocky planets. In contrast, only ~50 discs (~1/3 of the\nsample) have enough mass in the form of dust to form the canonical 10 M_Earth\ncore needed to trigger runaway gas accretion and the formation of gas giant\nplanets, although the total mass of solids already incorporated into bodies\nlarger than cm scales is mostly unconstrained. The distribution in continuum\ndisc sizes in our sample is heavily weighted towards compact discs: most\ndetected discs have radii < 15 au, while only 23 discs (~15% of the targets)\nhave radii > 30 au.\n