This Is How the Solar System Was Born... The "Moment of Crystallization" Captured by James Webb [Reading Science]

Professor Jeong-Eun Lee's Team at Seoul National University
First to Uncover Mechanism of Silicate Formation and Transport During Star Birth

A Korean research team has unveiled, through direct observation, a key process in the early stages of solar system and planet formation. For the first time in the world, the team captured the moment when silicates crystallize during star formation and the mechanism by which these materials are transported outward, using the James Webb Space Telescope (JWST).

On January 22, the Ministry of Science and ICT announced that Professor Jeong-Eun Lee's team at Seoul National University had observed that explosive mass accretion bursts occurring during the star formation process heat the inner region of the protoplanetary disk to high temperatures, crystallizing silicates, and that these newly formed materials can be transported outward. This research was supported by the Ministry’s Basic Research Program (Mid-career Researcher and Basic Research Laboratory).

Mid-infrared Spectral Observation of the Protostar EC 53 by the James Webb Space Telescope (J.-E. Lee et al. 2026, Nature). The above image shows the spectrum of the protostar EC 53 observed with the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI). During the outburst phase (red), the brightness increases more than threefold compared to the quiescent phase (blue), with a distinct silicate absorption feature around 10μm. The graph below compares the brightness ratio between the outburst and quiescent phases, confirming a significant increase in the 10μm region. This suggests that silicate components were newly formed inside the protoplanetary disk during the outburst phase. Provided by Professor Lee Jeongeun, Department of Physics and Astronomy, Seoul National University.

Silicates are essential minerals that make up terrestrial planets and comets. In particular, crystalline silicates are known to form only in high-temperature environments above 600°C. However, the discovery of crystalline silicates in comets originating from the extremely cold outer solar system left a long-standing question as to how materials formed at high temperatures could be transported to such distant regions.

The research team utilized observation time with the James Webb Space Telescope-secured solely by Korean researchers-to focus on the protostar EC 53 located in the Serpens Nebula. EC 53 is an astronomical object whose brightness varies on an approximately 18-month cycle, allowing for a clear distinction between its quiescent and outburst phases. The researchers used JWST’s Mid-Infrared Instrument (MIRI) to conduct comparative spectral observations during both phases.

Schematic Diagram of Silicate Crystallization and Redistribution by Magnetohydrodynamic Disk Winds (J.-E. Lee et al. 2026, Nature). This illustration depicts the crystallization and migration processes of silicates occurring in the protoplanetary disk during the explosive phase. The left side shows the temperature distribution inside the disk during the explosion phase along with the crystallization zones of crystalline pyroxene (light green) and olivine (green). The right side illustrates the process of formed crystalline silicates mixing and migrating. These silicates can be lifted from the disk surface and transported to the outer regions by magnetohydrodynamic (MHD) disk winds, suggesting that vertical mixing within the disk increases the crystalline silicate fraction at the midplane within a few years. Provided by Professor Jeong-Eun Lee, Department of Physics and Astronomy, Seoul National University

As a result, a distinctive infrared signal characteristic of crystalline silicates was detected only during the outburst phase. Analysis confirmed that these were crystalline olivine and pyroxene, newly formed in the hot inner disk close to the protostar. This provides direct observational evidence that silicate crystallization indeed occurs during the explosive evolutionary phase early in star formation.

The team also revealed that crystalline silicates formed in the inner disk can be transported to the cold outer disk by disk winds. This finding suggests that the origin and movement of crystalline silicates in comets can be explained by a unified physical scenario.

Photo of the research team. Provided by Seoul National University

This research was published on January 21 (local time) in the international journal Nature under the title, "Accretion bursts crystallize silicates in a planet-forming disk."

Professor Jeong-Eun Lee, who led the research, stated, "This is a case where theoretical predictions accumulated over many years have been confirmed by observations with the James Webb Space Telescope," and added, "Through follow-up observations, we plan to verify whether silicate crystallization and material transport processes are universally observed in other stars as well."

This achievement not only provides an important benchmark for understanding planetary system formation processes around other stars as well as our solar system, but is also regarded as a new milestone for time-series observational research using the James Webb Space Telescope.