Gallery: Polaris

This gallery exhibits movies, photos, and plots of the works that were made by utilizing the high performance computer Polaris. You are strongly encouraged to send your contributions to Dr. Jongsoo Kim.

Core Formation in a Molecular Cloud

To study core formation in a turbulent molecular cloud, Wankee Cho (SNU) and Jongsoo Kim (KASI) performed three-dimensional magnetohydrodynamic simulations with self-gravity. The following plot shows volume renderings of density fields at two different times. After generating a fully saturated turbulent flow, they turned on self-gravity of the molecular cloud and set the time zero. The left panel shows a density image at that time and the right one does at 1.2 free-fall time. You can see the formation of high density cores in the right panel. This work was published in Cho & Kim (2011).

A Numerical Code for a Dusty Interstellar Cloud

To study collapse dynamics of a starless core, Young Min Seo (KASI), Jongsoo Kim (KASI) and Seung Soo Hong (SNU) have written a one-dimensional numerical code that simulates a dusty cloud embedded in an inter-cloud medium. The code solves governing equations of two-phase gaseous media using a Godunov type scheme. The interface between the cloud and inter-cloud media is tracked by a mesh in the arbitrary Lagrangian-Eulerian frame. The dust component is treated as either a pressureless continuum or super-particles. The following plot shows physical properties of a collapsing dusty cloud embedded in an inter-cloud medium and interstellar radiation field. The time epochs are written at the top of each column. Each column contains the density (first row), the velocity (second row), the dust-to-gas ratio (third row) and the optical depth (fourth row) as functions of the radial distance. In the fifth row, the projected optical depth is plotted as functions of the projected distance p. The solid lines in the panels of the density and velocity represent the gas component, and the dashed lines do the dust grains. The initial density structure of cloud is a stable Bonnor-Ebert sphere of ximax = 4.5 with its number density of hydrogen molecules at the cloud center being nH2 = 103 cm-3. The radius of dust grains is 0.1 m. The intensity of lights irradiated onto the cloud is about half the strength of the diffuse interstellar radiation field. You can see that the cloud is compressed by the radiation pressure and collapses. This work is published in Seo, Kim & Hong (2011).