Experimental study on the heating of silicate aggregates and the formation of chondrules by nebula shock

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We have developed a new instrument to generate a strong shock wave with a large Mach number in gas. This instrument was consisted of a two-stage light gas gun and a small high-pressure vessel set in a sample chamber evacuated in a vacuum. Collisions among nebula gas and the dust-gas interaction in a generated shock wave were simulated with this instrument. A nylon projectile with the size of 1.6mm was launched into the high-pressure vessel filled with 1 bar air and this projectile generates a strong shock wave after it penetrates into the air. We have observed a bow shock with the Mach number larger than 9 around the projectile by using a high-speed photography, but we didn't observe any emission from the shock compressed gas and the surface of the projectile heated by gas drag. The projectile was observed to be intact without any disruption and melting after the penetration into the gas.We have also studied a disruption experiment of a water droplet by high velocity gas flow. This study simulates a completely molten silicate droplets caused by nebula shock, which are compressed or sheared by gas drag. The disrupted silicate melts could be related to the origin of chondrules based on the evidence such as the size distribution and the characteristics of the shape. We have conducted this experiment with a water droplet whose size is 0.3 to 5mm at the condition with the Mach number from 1.01-1.12 by using a shock tube in air. The disruption was observed by a high-speed digital video and the size distribution of the disrupted droplets was analyzed. Our result shows that the disrupted droplets have an exponential relationship for the cumulative mass distribution and the slope of this exponential relation is found to depend on a Weber number (4-400)