Can the Central Star Influence the Substructure Formation in a Protoplanetary Disk?

Abstract Substructures are ubiquitous in a protoplanetary disk as observed, which give them distinct features such as annular gaps, rings, vortices, etc. An embedded planet or pair of planets is generally studied to analyze their role in creating such structures. Using a numerical approach, we model such a star–disk system with two Neptune-sized planets embedded in a low viscous gas disk for probing changes resulting from changes in the properties of its central star. With different interplanetary spacing, the position and strength of structures formed by the planet pair are found to depend on the stellar mass, which results from a change in the planet-to-star mass ratio “q.” Following previously defined regimes of structure formation for “ m p / M th < 1,” we extend the fitting for different stellar masses for both “ m p / M th > 1” and “ m p / M th < 1.” We find that a thinner disk with a lower-mass star in the center readily forms structures that are greatly deformed due to repeated interaction with the spiral wakes of nearby planets. On the other hand, a thicker disk has a slower rate of structure formation, with every formed structure appearing to be highly stretched in the disk around a heavier star. For planet pairs with period ratios close to commensurability, strong mean motion resonance was not formed due to negligible convergent migration, thereby enhancing our understanding of the limiting conditions of such resonance. However, such planet pairs are seen to facilitate strong vortices, which favor dust traps, contributing to future planet formation after reaching a quasi-steady state.