Non-monotonic spatial distribution of the interstellar dust in astrospheres: finite gyroradius effect

TL;DR

This paper models how charged dust grains in astrospheres, influenced by magnetic fields, create filamentary structures due to gyrorotation, explaining observed mid-infrared filament patterns.

Contribution

It introduces a numerical model linking dust grain gyrorotation to filament formation in astrospheres, highlighting the role of charge-to-mass ratio.

Findings

Filamentary dust structures arise from specific gyrorotation periods.

Number of filaments depends on dust charge-to-mass ratio.

Non-monotonic dust distribution explains observed filaments.

Abstract

High-resolution mid-infrared observations of astrospheres show that many of them have filamentary (cirrus-like) structure. Using numerical models of dust dynamics in astrospheres, we suggest that their filamentary structure might be related to specific spatial distribution of the interstellar dust around the stars, caused by a gyrorotation of charged dust grains in the interstellar magnetic filed. Our numerical model describes the dust dynamics in astrospheres under an influence of the Lorentz force and assumption of a constant dust charge. Calculations are performed for the dust grains with different sizes separately. It is shown that non-monotonic spatial dust distribution (viewed as filaments) appears for dust grains with the period of gyromotion comparable with the characteristic time scale of the dust motion in the astrosphere. Numerical modelling demonstrates that number of filaments depends on charge-to-mass ratio of dust.