7 May 2017 to 2 June 2017
Nordita, Stockholm
Europe/Stockholm timezone

Phase Transition Dynamics of ISM: The Formation of Molecular Clouds and Galactic Star Formation

22 May 2017, 11:00
1h
122:026 (Nordita, Stockholm)

122:026

Nordita, Stockholm

Speaker

Prof. Shu-ichiro Inutsuka

Description

Magnetohydrodynamics of interstellar medium is remarkably different from that of simple barotropic gas owing to the phase transitions between cold phase and warm phase (and hot phase) that trigger variety of instabilities. Identifications of distinct instabilities in various stages provide us important clues for understanding the saturation levels of turbulent energies and rates of formation and destruction of cold clouds, such as HI clouds and molecular clouds. Recent high- resolution magneto-hydrodynamical simulations of phase transition dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds requires multiple episodes of supersonic compression. This finding enables us to create a new scenario of molecular cloud formation as the interacting shells or bubbles in galactic scale, which explains many observational properties such cloud-to-cloud velocity dispersions, accelerating star formation, and very low star formation efficiencies in filamentary molecular clouds. We estimate the ensemble-averaged growth rate of individual molecular clouds, and predict the associated cloud mass function. Cloud-cloud collisions as a mechanism for forming massive stars and star clusters can be naturally accommodated in this scenario. This explains why massive stars formed in cloud-cloud collisions follows the power-law slope of the mass function of molecular cloud cores repeatedly found in low-mass star forming regions.

Primary author

Prof. Shu-ichiro Inutsuka

Presentation materials