Abstract
In a shock-wave heating model, a chondrule is formed through frictional heating between a chondrule precursor and gas. If the gas dynamic pressure is greater than tensile strength of a precursor, a precursor is broken into small pieces. I examined the possibility of survival of a precursor, which is assumed as a grain aggregate, by calculating tensile strengths of an aggregate. I found that sintering greatly changes the strength of an aggregate, caused by the radiation emitted from the frictionally heated precursor in the downstream side of a shock wave. Densification due to sintering prevents an aggregate from breakup if the temperature of an aggregate is sufficiently high. On the contrary, small degree of sintering promotes breakup of an aggregate because it makes rolling of grains difficult. The critical filling factor (volume fraction occupied by grains) of an aggregate below which breakup occurs is estimated based on experimental data. Sintering is important for the evolution of grain aggregates in the solar nebula.
