Gaia EDR3 comparative study of protoplanetary disk fractions in young stellar clusters

Abstract

Context. The lifetime of protoplanetary disks around young stars limits the timescale of planet formation. A disk dissipation timescale ≤10 Myr was inferred from surveys that count the relative number of stars with disks – the disk fraction – in young stellar clusters with different ages. However, most previous surveys focused on the compact region within ∼2 pc of the clusters’ centers, for which the disk fraction information about the outer part is practically absent. Aims. We aim to test if disk fraction estimates change when inferred from an extended region around the clusters’ centers. Methods.Gaia EDR3 data and a best-suited, Virtual Observatory (VO)-based tool – Clusterix – are used to identify member stars for a representative sample of 19 young stellar clusters considering two concentric fields of view (FOVs) with radii of ∼20 pc and ∼2 pc. Inner-disk fractions associated with each FOV are identically derived from 2MASS color-color diagrams and compared to each other. Results. Although the density of members is smaller in the periphery, the absolute number of member stars is typically ∼5 times larger at distances farther than ∼2 pc from the clusters’ centers. In turn, our analysis reveals that the inner disk fractions inferred from the compact and the extended regions are equal within ∼±10%. A list of member and disk stars identified in each cluster is provided and stored in a VO-compliant archive, along with their membership probabilities, angular distances to the center, and Gaia and near-infrared data. Averaged values and plots that characterize the whole clusters are also provided, including Hertzsprung-Russell diagrams based on Gaia colors and absolute magnitudes for the sources with known extinction. Conclusions. Our results cover the largest fields ever probed when dealing with disk fractions for all clusters analyzed, and imply that their complete characterization requires the use of wide FOVs. However, the comparative study does not support a previous hypothesis that disk fractions should be significantly larger when extended regions are considered. The resulting database is a benchmark for future detailed studies of young clusters, whose disk fractions must be accurately determined by using multiwavelength analysis potentially combined with data from upcoming Gaia releases.