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 aiming to study the entire population of Spitzer -selected protoplanetary discs in the Ophiuchus Molecular Cloud (∼300 objects) from both millimeter continuum and CO isotopologues data. Here we present 1.3 mm/230 GHz continuum images of 147 targets at 0.2 (28 au) resolution and a typical rms of 0.15 mJy. We detect a total of 133 discs, including the individual components of 11 binary systems and 1 triple system. Fifty-three of these discs are spatially resolved. We find clear substructures (inner cavities, rings, gaps, and/or spiral arms) in 8 of the sources and hints of such structures in another 4 discs. We construct the disc luminosity function for our targets and perform comparisons to other regions. A simple conversion between flux and dust mass (adopting standard assumptions) indicates that all discs detected at 1.3 mm are massive enough to form one or more rocky planets. In contrast, only ∼50 discs (∼1/3 of the sample) have enough mass in the form of dust to form the canonical 10 M ⊕ core needed to trigger runaway gas accretion and the formation of gas giant planets, although the total mass of solids already incorporated into bodies larger than cm scales is mostly unconstrained. The distribution in continuum disc sizes in our sample is heavily weighted towards compact discs: most detected discs have radii < 15 au, while only 23 discs (∼15% of the targets) have radii > 30 au.

Dust Polarization toward Embedded Protostars in Ophiuchus with ALMA. III. Survey Overview

“…7. Most of the disks in our sample have masses below the minimum mass solar nebula and sizes < 30 au, in agreement with the Class II disks reported by Cieza et al (2019). We find that our sample of disks follow a surface density relation of Σ ∼ r −(0.9−0.6) .…”

“…Figure 2 shows that the field also contains 4 additional compact objects, including a more evolved YSO, IRS 39, 15 southwest of the phase center. Several of the aforementioned compact objects were also detected by Cieza et al (2019) in their ALMA 1.3 mm emission. We use a similar naming scheme as Cieza et al (2019), Figure A8.…”

Formation of planetary populations − II. Effects of initial disc size and radial dust drift

“…These observed disks surrounding a range of host-stellar masses have gas radii in the range of 63-500 AU at an age of ∼ 1-3 Myr. We emphasize, however, that these large, extended disks are the exception and are not indicative of typical disks that are much more compact, as indicated by numerous observations showing dust radii of 20 − 30 AU (Barenfeld et al 2016(Barenfeld et al , 2017Cox et al 2017;Hendler et al 2017;Tazzari et al 2017;Cieza et al 2019;Long et al 2019).…”

Are the observed gaps in protoplanetary discs caused by growing planets?

“…(ii) Planet formation simulations are missing some important ingredients regarding gas accretion (see also Nayakshin et al (2019)) and planet migration. The survey by Long et al (2018) in the Taurus star-forming region and the survey by Cieza et al (2019) in the Ophiuchus starforming region, on the other hand, found a significant population of very compact discs (outer disc radii ¡ 30 au). These discs are not pictured within the DSHARP sample, due to the selection biases in the DSHARP campaign (Andrews et al 2018).…”