1. Effect of Impact Velocity and Angle on Deformational Heating and Postimpact Temperature.
- Author
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Wakita, S., Genda, H., Kurosawa, K., Davison, T. M., and Johnson, B. C.
- Subjects
FRICTION velocity ,VELOCITY ,STRENGTH of materials ,HEATING ,ANGLES ,EXTRATERRESTRIAL beings ,SURFACE waves (Seismic waves) ,ASTEROIDS - Abstract
The record of impact‐induced shock heating in meteorites is an important key for understanding the collisional history of the solar system. Material strength is important for impact heating, but the effect of impact angle and impact velocity on shear heating remains poorly understood. Here, we report three‐dimensional oblique impact simulations, which confirm the enhanced heating due to material strength and explore the effects of impact angle and impact velocity. We find that oblique impacts with an impact angle that is steeper than 45‐degrees produce a similar amount of heated mass as vertical impacts. On the other hand, grazing impacts produce less heated mass and smaller heated regions compared to impacts at steeper angles. We derive an empirical formula of the heated mass, as a function of the impact angle and velocity. This formula can be used to estimate the impact conditions (velocity and angle) that occurred and caused Ar loss in the meteoritic parent bodies. Furthermore, our results indicate that grazing impacts at higher impact velocities could generate a similar amount of heated material as vertical impacts at lower velocities. As the heated material produced by grazing impacts has experienced lower pressure than the material heated by vertical impacts, our results imply that grazing impacts may produce weakly shock‐heated meteorites. Plain Language Summary: Meteorites are extraterrestrial materials that have been delivered to the Earth from asteroids. The materials in meteorites can record information about their formation and subsequent evolution. Thus, they are excellent sources of information used to explore the history of the solar system. One such feature recorded is evidence of shock: high pressures and temperatures caused by collisions between asteroids. Previous work investigating impacts found that material strength is a key factor in determining the amount of impact heating, especially in low speed collisions like those expected to occur in the main asteroid belt. In this work, we explore various oblique incidence impacts to study the effects of material strength by using a shock physics model. We confirm that material strength plays a key role in oblique impacts, just as in head‐on impacts. Our results show that head‐on and 45‐degree impacts can generate nearly the same amount of heated mass in total. However, more oblique impacts with a shallower angle produce less heated mass than other steeper‐angle impacts (i.e., head‐on and 45‐degree impacts). We also find that low speed vertical impacts and high speed grazing impacts can produce the same amount of material in asteroids that have experienced a given temperature. Key Points: We examined the dependence of impact heating on impact angle and velocity using a shock physics codeThe amount of heated mass is similar among >45° impacts, while it is smaller for shallower impactsWe derived an empirical formula for the cumulative heated mass over 1000 K during oblique impacts [ABSTRACT FROM AUTHOR]
- Published
- 2022
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