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From the magnetized diffuse interstellar medium to the stars

Final Report Summary - MAGMIST (From the magnetized diffuse interstellar medium to the stars)

Understanding star formation remains one of the greatest challenges of modern astronomy. Indeed, stars are playing a fundamental role in the story of our universe as they are responsible of the synthesis of heavy elements such as carbon and oxygen, but also because of they host planets and considerably influence the evolution of galaxies. The main difficulties, which have been restricting the development of this field, are on one hand the huge dynamics of spatial and temporal relevant scales and on the hand the great variety and non-linearity of the physical processes involved in the formation of stars.

The methodology used in the MAGMIST project has been specifically designed to address the multi-scale nature of the star formation process. This includes studies at different scales but also studies that aimed at bridging and connecting various scales. The most important conclusions of the MAGMIST project are as follows:

-the prestellar dense cores, which constitute the mas reservoir of stars and are possibly responsible of setting the stellar mass function, are likely a consequence of gravity and magneto-hydrodynamical turbulence that develop in the interstellar medium, as most of their properties can nicely be reproduced from self-consistent zooming simulations. Unlike previous calculations, ours do not make restricting assumptions on the initial conditions since all structures are formed self-consistently from much larger scales

-feedback processes due to ionising radiation and supernovae remnants are playing, together with magnetic field and turbulence, a determinant role to regulate the star formation rate and the whole ISM structure and dynamics. The star formation rate obtained are very close to the ones inferred observationally

-the initial mass function is largely set-up by local physical processes, which includes the physics of gravitational collapse, the stabilising influence of tidal forces and the gas thermodynamics due, in particular to dust opacity. This renders the final stellar initial mass function relatively insensitive to the large scale conditions and suggests a relative universality of the IMF in good agreement with observation

-the early planet-forming disks, that form around young protostars, are also largely due to local processes, namely magnetic braking and magnetic flux diffusion. This also makes their properties relatively universal provide the magnetic field is strong enough.