Collisional Consequences of Big Interstellar Grains

Abstract

Identification by the Ulysses spacecraft of interstellar grains inside the planetary system provides a new window for the study of diffuse interstellar matter. Dust particles observed by Ulysses and confirmed by Galileo are more massive ($\ge 10^{-13}\mathrm{g}$) than the 'classical' interstellar grains. Even bigger grains ($\approx 10^{-7}\mathrm{g}$) were observed in form of interstellar meteors. We analyze the consequences of the plentiful existence of massive grains in the diffuse interstellar medium. Astronomically observed 'classical' interstellar grains can be described by a size distribution ranging from about 5 to 250 nm in radius (about $10^{-18}$ to $10^{-13}\mathrm{g}$). Lifetimes of these particles, due to mutual collisions in interstellar space, can be as short as $10^{5}f$ years, where f = 10 to 1000, is the fraction of total lifetime to the time when grains are exposed to supernova shocks. Shattering is a source of the smallest of these grains, but grains more massive than about $10^{-16}\mathrm{g}$ of the classical interstellar grain population are rapidly destroyed. When applying the same shattering mechanism to the more massive grains found recently, we suggest that collisions of particles bigger than about $10^{-15}\mathrm{g}$ provide a source for smaller grains. Because massive grains couple to the interstellar gas only over large (100 to 1000 pc) length scales, the cosmic abundance ratio of gas-to-dust needs only to be preserved averaged over corresponding volumes of space.

9 pages, 4 figures, to appear in JGR

References in corpus (3)

• Dust in the Local Interstellar Wind
• Aspects of the Mass Distribution of Interstellar Dust Grains in the Solar System from In-Situ Measurements
• Modeling the Motion and Distribution of Interstellar Dust inside the Heliosphere

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• Three years of Ulysses dust data: 2005 to 2007
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• Techniques for Galactic Dust Measurements in the Heliosphere
• Evidence for an interstellar dust filament in the outer heliosheath
• Is the Sun Embedded in a Typical Interstellar Cloud?
• Why Study Interstellar Matter Very Close to the Sun?
• Synergies between interstellar dust and heliospheric science with an Interstellar Probe
• Error dependencies in the space-based CNEOS fireball database
• Solid grains ejected from terrestrial exoplanets as a probe of the abundance of life in the Milky Way