Efficient Dust Radial Drift Around Young Intermediate-mass Stars

TL;DR

This paper studies how the rapid increase in dust radial drift velocity around intermediate-mass stars after 1-2 million years may hinder planet formation, explaining the scarcity of observed planets around such stars.

Contribution

It introduces a model considering stellar evolution effects on dust radial drift, highlighting a potential barrier to planet formation around intermediate-mass stars.

Findings

Radial drift velocity sharply increases after 1-2 Myr around intermediate-mass stars.

High radial drift may prevent planet formation in disks of intermediate-mass stars.

Disks around low-mass stars are less affected by radial drift, allowing planet formation.

Abstract

The radial velocities and direct imaging observations of exoplanets have suggested that the frequency of giant planets may decrease for intermediate-mass stars ($2.5-8\,M_\odot$). The key mechanism that could hinder their formation remains unclear. From a theoretical point of view, planet formation around intermediate-mass stars may take place on longer timescales, which -- coupled with fast migration and efficient photoevaporation -- may prevent planetary formation in these environments. In this letter, we investigate the temporal evolution of the radial drift for dust particles in disks when stellar evolution is taken into account. We demonstrate that the particle drift velocity around intermediate-mass stars sharply increases after 1$-$2 Myr, potentially forming a difficult barrier to overcome in the first steps of planet formation. This high radial drift could explain the lack of disk detections around intermediate-mass stars older than 3$-$4 Myr, as opposed to low-mass stars ($<2.5\,M_\odot$), where the drift may not be the most impactful factor for the disk evolution. Future high-resolution images of these disks can help us to explain why planets around intermediate-mass stars may be rare. In addition, we can explore whether the role of efficient dust radial drift does in fact hinder planet formation around intermediate-mass stars -- or otherwise.