Abstract
Crystalline silicates form at high temperatures (>900 K) (refs. 1,2). Their presence in comets[3](#ref-CR3 “Hanner, M. S., Lynch, D. K. & Russell, R. W. The 8–13 micron spectra of comets and the compo…
Abstract
Crystalline silicates form at high temperatures (>900 K) (refs. 1,2). Their presence in comets3,4,5,6 suggests that high-temperature dust processing occurred in the early Solar System and was subsequently transported outwards to comet-forming regions. However, direct evidence for this crystallization and redistribution in Sun-like protostars has remained unknown. By comparing James Webb Space Telescope mid-infrared spectra of the periodically bursting protostar EC 53 (ref. 7), we detect crystalline silicate (forsterite and enstatite) emission features that appear only during the burst. The emergence of these features indicates active crystal formation by thermal annealing in the hot inner disk during the accretion burst. We also detect a nested outflow—a collimated atomic jet enclosed by slower molecular outflows, consistent with magnetohydrodynamic wind models8. This configuration provides a mechanism for the outward transport of freshly crystallized silicates9. To our knowledge, our results provide the first direct observational evidence of in situ silicate crystallization during episodic accretion bursts in a very young star still embedded in its dense envelope. Although we do not directly detect grains transported to the outer disk, the observed trends are consistent with outward redistribution, indicating that both dust processing and transport occur during the earliest and most dynamic stages of star formation.
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Data availability
The JWST MIRI raw data were reprocessed using the JWST Calibration Pipeline v1.18.063 with the Calibration Reference Data System64 mapping jwst_1364.pmap. The standard pipeline-reduced data are publicly available via the MAST portal (https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html) and through the DOI (https://doi.org/10.17909/fwwz-kt92). This paper also makes use of JWST NIRCam imaging data62 obtained from the MAST archive. The ALMA data (project code: ADS/JAO.ALMA#2022.1.00800.S) are available from the ALMA Science Archive (https://almascience.nrao.edu/alma-data/archive). The reduced MIRI and ALMA data are available from the corresponding author upon request.
Code availability
We provide access to GitHub repositories containing the codes developed for continuum and broad silicate fitting (https://github.com/JY-Kim8502/JKAS_IRS_Continuum_fitting_with_Slicate) and JWST astrometry and silicate emission fitting (https://github.com/SNUSF/EPISODE). The Python packages used in this study are publicly available at GitHub: RADMC-3D (https://github.com/dullemond/radmc3d-2.0), optool (https://github.com/cdominik/optool) and emcee (https://github.com/dfm/emcee). The JWST Calibration Pipeline is publicly available at GitHub (https://github.com/spacetelescope), with documentation on installation, execution and CRDS configuration at https://jwst-pipeline.readthedocs.io/en/latest/.
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Acknowledgements
This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract NAS 5-03127 for JWST. These observations are associated with the JWST GO Cycle 2 program ID 3477. J.D.G. acknowledges support from the associated 3477 NASA observer grant. J.-E.L., C.-H.K., Seonjae Lee and Y.-J.K. were supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (grant nos. 2021R1A2C1011718 and RS-2024-00416859). G.B. was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (RS-2023-00247790). D.J. is supported by NRC Canada and by an NSERC Discovery Grant. Y.A. acknowledges support by JSPS KAKENHI grant no. 24K00674. Y.-L.Y. acknowledges support from Grant-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (20H05844 and 25H00676). Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). We acknowledge the use of ChatGPT for checking English grammar and improving the clarity of expressions.
Author information
Authors and Affiliations
Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea
Jeong-Eun Lee, Chul-Hwan Kim, Young-Jun Kim, Seonjae Lee & Giseon Baek 1.
SNU Astronomy Research Center, Seoul National University, Seoul, Republic of Korea
Jeong-Eun Lee 1.
Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea
Jaeyeong Kim & Seokho Lee 1.
Research Institute of Basic Sciences, Seoul National University, Seoul, Republic of Korea
Giseon Baek 1.
Space Telescope Science Institute, Baltimore, MD, USA
Joel D. Green 1.
Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing, China
Gregory J. Herczeg 1.
Department of Astronomy, Peking University, Beijing, China
Gregory J. Herczeg 1.
NRC Herzberg Astronomy and Astrophysics, Victoria, Brit