2011MNRAS.416..439E

We address the question of whether protoplanetary discs around low-mass stars (e.g. M-dwarfs) may be longer lived than their solar-type counterparts. This question is particularly relevant in assessing the planet-making potential of these lower mass discs. Given the uncertainties inherent to age-dating young stars, we propose an alternative approach that is to analyse the spatial distribution of disc-bearing low-mass stars and compare it to that of disc-bearing solar-type stars in the same cluster. A significant age difference between the two populations should be reflected in their average nearest-neighbour distance (normalized to the number of sources), where the older population should appear more spread out.

To this aim, we perform a Minimum Spanning Tree (MST) analysis on the spatial distribution of disc-bearing young stellar objects (YSOs) in six nearby low-mass star-forming regions. We find no evidence for significant age differences between the disc-bearing low-mass (later than M2) and `solar-type' (earlier than M2) stars in these regions. We model our results by constructing and analysing synthetic fractal distributions that we evolve for typical values of the velocity dispersions. A comparison of results obtained using simple models to the results from our MST analysis suggests that the lifetime of discs around M-stars is similar to that of discs around solar-type stars. Furthermore, a model-independent spatial analysis of the observations robustly shows that any age differences between the two samples must be smaller than the average age difference between disc-bearing classical T Tauri stars and discless weak-lined T Tauri stars.