Trajectories and Distribution of Interstellar Dust Grains in the Heliosphere

Abstract

The solar wind carves a bubble in the surrounding interstellar medium (ISM), known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dust density distributions that result. We include up-to-date grain charging calculations using a realistic UV radiation field and full 3-D magnetohydrodynamic fluid + kinetic models for the heliosphere. Models with two different (constant) polarities for the solar wind magnetic field (SWMF) are used, with the grain trajectory calculations done separately for each polarity. Small grains a_gr ~ 0.01 micron are completely excluded from the inner heliosphere. Large grains, a_gr ~ 1.0 micron pass into the inner solar system and are concentrated near the Sun by its gravity. Trajectories of intermediate size grains depend strongly on the SWMF polarity. When the field has magnetic north pointing to ecliptic north, the field de-focuses the grains resulting in low densities in the inner heliosphere, while for the opposite polarity the dust is focused near the Sun. The ISDG density outside the heliosphere inferred from applying the model results to in situ dust measurements is inconsistent with local ISM depletion data for both SWMF polarities, but is bracketed by them. This result points to the need to include the time variation in the SWMF polarity during grain propagation. Our results provide valuable insights for interpretation of the in situ dust observations from Ulysses.

34 pages, 15 figures, Accepted for publication in the Astrophysical Journal

References in corpus (7)

• The Structure of the Local Interstellar Medium V: Electron Densities
• The Ubiquity of Micrometer-Sized Dust Grains in the Dense Interstellar Medium
• The effects of a kappa-distribution in the heliosheath on the global heliosphere and ENA flux at 1 AU
• The Boundary Conditions of the Heliosphere: Photoionization Models Constrained by Interstellar and In Situ Data
• Probing Heliospheric Asymmetries with an MHD-kinetic Model
• Perspectives on Interstellar Dust Inside and Outside of the Heliosphere
• The Interstellar H Flow: Updated Analysis of SOHO/SWAN Data

Cited by in corpus (14)

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• 16 years of Ulysses Interstellar Dust Measurements in the Solar System: II. Fluctuations in the Dust Flow from the Data
• Heliospheric modulation of the interstellar dust flow on to Earth
• Modelling DESTINY+ interplanetary and interstellar dust measurements en route to the active asteroid (3200) Phaethon
• Correcting the record on the analysis of IBEX and STEREO data regarding variations in the neutral interstellar wind
• Interstellar Dust in the Solar System: Model versus In-Situ Spacecraft Data
• Evidence for an interstellar dust filament in the outer heliosheath
• Dust Formation By Failed Supernovae
• Interstellar Dust Close to the Sun
• Effects of dispersion of the dust velocity in the LISM on the interstellar dust distribution inside the heliosphere
• Dynamical charging of interstellar dust particles in the heliosphere
• Synergies between interstellar dust and heliospheric science with an Interstellar Probe
• A solar rotation signature in cosmic dust: frequency analysis of dust particle impacts on the Wind spacecraft
• Nearby Supernova and Cloud Crossing Effects on the Orbits of Small Bodies in the Solar System