Interaction of the solar wind with comets: a Rosetta perspective

Area of Science:

• Space Physics
• Cometary Science
• Plasma Physics

Background:

• Comet-solar wind interactions are crucial for understanding cometary magnetospheres.
• Previous studies offered limited temporal insights into these interactions.
• The Rosetta mission provided continuous observation of comet 67P/Churyumov-Gerasimenko.

Purpose of the Study:

• To investigate the temporal evolution of the innermost cometary magnetosphere.
• To analyze the physics of mass loading at various cometary activity levels.
• To characterize plasma instabilities and their impact on solar wind interaction.

Main Methods:

• In-situ measurements by the Rosetta spacecraft around comet 67P/Churyumov-Gerasimenko.
• Analysis of plasma boundaries and wave phenomena.
• Studying the temporal dynamics of the cometary magnetosphere from low activity to perihelion.

Main Results:

• Identified large-amplitude ultra-low-frequency (ULF) waves, likely from a modified ion Weibel instability.
• Observed initial pick-up of cometary ions causing significant solar wind proton deflection.
• Characterized a threefold structure in the inner interaction region, including Mach cone and Whistler wings.

Conclusions:

• Rosetta's observations reveal the dynamic evolution of a cometary magnetosphere.
• The study elucidates the role of plasma instabilities and ion pick-up in shaping comet-solar wind interactions.
• The findings provide a comprehensive understanding of stationary and dynamic features in the innermost cometary interaction region.