Abstract
Context. Demographic surveys of protoplanetary disks, carried out mainly with the Atacama Large Millimeter/submillimete Array, have provided access to a large range of disk dust masses (Mdust) around stars with different stellar types and in different star-forming regions. These surveys found a power-law relation between Mdust and M⋆ that steepens in time, but which is also flatter for transition disks (TDs). Aims. We aim to study the effect of dust evolution in the Mdust−M⋆ relation. In particular, we are interested in investigating the effect of particle traps on this relation. Methods. We performed dust evolution models, which included perturbations to the gas surface density with different amplitudes to investigate the effect of particle trapping on the Mdust−M⋆ relation. These perturbations were aimed at mimicking pressure bumps that originated from planets. We focused on the effect caused by different stellar and disk masses based on exoplanet statistics that demonstrate a dependence of planet mass on stellar mass and metallicity. Results. Models of dust evolution can reproduce the observed Mdust−M⋆ relation in different star-forming regions when strong pressure bumps are included and when the disk mass scales with stellar mass (case of Mdisk = 0.05 M⋆ in our models). This result arises from dust trapping and dust growth beyond centimeter-sized grains inside pressure bumps. However, the flatter relation of Mdust − M⋆ for TDs and disks with substructures cannot be reproduced by the models unless the formation of boulders is inhibited inside pressure bumps. Conclusions. In the context of pressure bumps originating from planets, our results agree with current exoplanet statistics on giant planet occurrence increasing with stellar mass, but we cannot draw a conclusion about the type of planets needed in the case of low-mass stars. This is attributed to the fact that for M⋆ < 1 M⊙, the observed Mdust obtained from models is very low due to the efficient growth of dust particles beyond centimeter-sizes inside pressure bumps.
Highlights
Censuses performed on the thousands of exoplanets that have been discovered far have revealed a large diversity of planetary architectures, along with a variety of trends that may be the result of the common physical processes ruling the formation and evolution of planets in disks around young stars
Motivated by the fact that exoplanet statistics show a dependence on stellar mass and metallicity, we focus on the effect of having different stellar and disk masses in the dust evolution models, assuming that the disk dust mass is a proxy of stellar metallicity
Our findings suggest that strong pressure traps can reproduce the Mdust−M relation observed in different star forming regions because of the trapping of dust particles and boulder formation inside pressure bumps, the latter in particular for M < 1 M
Summary
Censuses performed on the thousands of exoplanets that have been discovered far have revealed a large diversity of planetary architectures, along with a variety of trends that may be the result of the common physical processes ruling the formation and evolution of planets in disks around young stars. Exoplanet statistics show that giant planet occurrence increases with stellar metallicity and mass (e.g., Fischer & Valenti 2005; Johnson et al 2010), while sub-Neptune type planets are more common around M-dwarfs than around Sun-like stars (e.g., Mulders 2018). These observed trends stand as open challenges for current theories of planet formation, examining stellar and disk properties; in particular, questioning how the effects of the ratio between stellar mass and disk mass affect the final outcome of planet formation. This dust mass is usually used as a tracer of the total disk mass by assuming a constant dust-to-gas ratio, conventionally the interstellar medium ratio, that is, 1/100
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
