Invited Presentation

From Ices to Crystals: How Accretion Bursts Reveal and Process Planet-Forming Materials

Author(s): Jeong-Eun Lee (Seoul National University)

Presenter: Jeong-Eun Lee (Seoul National University)

Episodic accretion is now recognized as a fundamental part of low-mass star formation, yet its role in setting the chemical and mineralogical initial conditions for planet formation remains poorly understood. Accretion bursts provide unique natural experiments: the sudden increase in luminosity can both expose material that is normally hidden in cold regions of protoplanetary disks and thermally process solids in the hot inner disk.
In this talk, I will present two recent examples that illustrate these complementary effects. In the outbursting disk of V883 Ori, the greatly expanded snowline allows us to probe the molecular inventory released from sublimating ices in the disk midplane. Among the rich organic chemistry, we identify molecules such as methyl chloride (CH₃Cl), nitrous oxide (N₂O), and dimethyl sulfide (CH₃SCH₃), which are often discussed as candidate biosignature gases in exoplanetary atmospheres. Their presence in a young planet-forming disk highlights the importance of abiotic, pre-planetary chemistry when interpreting potential atmospheric biosignatures.
I will then turn to EC 53, a periodically accreting protostar observed with JWST at different phases of its burst cycle. The emergence of crystalline silicate features during the high-accretion state provides direct evidence that episodic heating can transform initially amorphous dust into crystalline material. These observations offer a new view of how high-temperature processing in the inner disk, followed by redistribution, may contribute to the crystalline silicates found in colder comet-forming regions.
Together, V883 Ori and EC 53 demonstrate that accretion bursts do more than temporarily brighten young stars. They reveal the inherited chemical inventory of planet-forming material while simultaneously reshaping its mineral composition. Episodic accretion may therefore play a central role in determining the mixture of inherited and processed material ultimately incorporated into planets.