Magik Star · MAGnetic fIeld and Kinematic coupling for massive STAR formation

MAGnetic fIeld and Kinematic coupling for massive STAR formation

Star formation is a fundamental process in astrophysics, the physical mechanisms of which have been studied for decades (see e.g., reviews by André et al. 2014, Krumholz et al. 2015). On large scales, it regulates the evolution of galaxies, while on small scales it determines the initial conditions for the formation of planetary systems. As of now, most of our knowledge is concentrated on the formation of stars of a few solar masses. If galaxies’ total stellar mass is dominated by low-mass stars, their energy budget is exclusively controlled by the enormous luminosity and powerful feedback of massive stars (Mstar > 8 Msun). Another interest in studying massive star-formation relates to the formation of atoms. Massive stars forge all the atoms listed in the Mendeleïev table with an atomic number exceeding eight (oxygen). This includes elements such as Sodium, Aluminium, Silicon, Sulfur, Potassium, Calcium, Iron, etc… These elements are fundamental to the chemical reactions on which life depends. Therefore, the understanding of Earth formation and the understanding of Life pass by the understanding of star formation — all types of stars. Despite their importance for forging most of the elements present on Earth, and for the life cycle of galaxies, the mechanisms leading to the formation of high-mass stars remain a mystery in many aspects. For instance, we do not know how were formed to most massive stars we know, a binary system of 300 and 150 Msun in the Tarantula nebula, located in the Large Magellanic Cloud. We do not know, in a star-formation event, if massive stars form first or last. We do not know what processes permit to counterbalance the pressure engendered by the luminosity of a massive protostar. We do not know how the massive dense cores (MDCs) form; MDCs are 2000-3000 au cloud structures denser than ten million of particles per cubic centimetres in which high-mass star forms. We do not know if a massive protostar accretes gas only from the MDC, or at (much) larger scale. The Magik-Star project focuses on the formation of these so-called massive dense cores, with two objectives: i) question the observational robustness of the massive dense core, and ii) quantify the impact of kinematics and magnetic fields onto massive dense cores.

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