Origin of Cavities in Cosmic Spherules

To examine the origin of the bubbles of cosmic spherules, we examine whether a bubble in forsterite dust particles entering Earth’s atmosphere grows or not. If the dust particle re‐solidifies before the bubble condenses, the bubble may be trapped inside the dust. In this study, assuming that the inside of the dust particle is isothermal and isobaric, we examined the bubble size by calculating the temperature and pressure of the dust particle for a wide variety of entry parameters. We found that the bubble is not trapped inside even if the bubble forms inside and grows because the bubble condenses before the dust particle re‐solidified. Therefore the bubble may be formed when volatile elements evaporate inside and are trapped inside.