MHD Simulations of the Evolution of the Local Interstellar Medium

Abstract

The Sun is located inside a low density cloud known as the Local Interstellar Cloud (LIC), which is part of a group of nearby clouds known as the Complex of Local Interstellar Clouds (CLIC). All of these clouds are contained within the hot Local Bubble, which contains gas at ∼ 106 K and appears to have been created by multiple supernova explosions. We present new results from our ongoing project on simulating the origins and evolution of the Local Interstellar Medium. We aim to model the origins of the CLIC, especially the way that the clouds managed to survive shock passage and reach their current warm (T ∼ 7000 K) and low density (n ∼ 0.2 cm−3) state. We find that the magnetic field is important for maintaining the Local Bubble at a high thermal pressure and helps the clouds rebound more effectively after being shocked. Thermal conduction is necessary to make the temperature in the bubble as uniform as observed. We also find that to reach its current state, the Local Bubble requires multiple supernova explosions. The state of the CLIC and the Local Bubble provide important clues as to how supernova feedback operates in the ISM and it interaction with the different phases of the ISM.