EPISODE IV: Ice Inventory in the Envelope of EC 53

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Main Authors: Kim, Jaeyeong, Lee, Jeong-Eun, Kim, Chul-Hwan, Lee, Seokho, Baek, Giseon, Lee, Seonjae, Yang, Yao-Lun, Aikawa, Yuri, Herczeg, Gregory J., Johnstone, Doug, Green, Joel D., Jeong, Woong-Seob
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Published: 2026
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author Kim, Jaeyeong
Lee, Jeong-Eun
Kim, Chul-Hwan
Lee, Seokho
Baek, Giseon
Lee, Seonjae
Yang, Yao-Lun
Aikawa, Yuri
Herczeg, Gregory J.
Johnstone, Doug
Green, Joel D.
Jeong, Woong-Seob
author_facet Kim, Jaeyeong
Lee, Jeong-Eun
Kim, Chul-Hwan
Lee, Seokho
Baek, Giseon
Lee, Seonjae
Yang, Yao-Lun
Aikawa, Yuri
Herczeg, Gregory J.
Johnstone, Doug
Green, Joel D.
Jeong, Woong-Seob
contents We present the 1.6$-$28 $μ$m spectra of the young protostar EC 53, obtained with JWST NIRSpec IFU and MIRI MRS during the quiescent and burst phases of its periodic brightness variations. To isolate ice absorption features, we modeled and removed the mid-infrared silicate dust absorption using a dedicated continuum-fitting procedure. In the optical depth spectrum, we first fit the broad H$_2$O ice features and then decomposed the major ice components, including NH$_3$, CO$_2$, CH$_3$OH, CO, and CH$_4$, by matching laboratory profiles for both pure and H$_2$O-mixed ices. The 4.62 $μ$m and 6.85 $μ$m bands are attributed to OCN$^-$ and NH$_4^+$ ions, respectively. Minor or tentative contributions from complex species (HCOOH, H$_2$CO, CH$_3$COOH, CH$_3$CHO, CH$_3$CH$_2$OH, and NH$_2$CHO) are also considered to our global ice analysis. The silicate-corrected spectra reveal no measurable change in any ice absorption band between the two phases, indicating that moderate and short-period accretion bursts in EC~53 do not significantly alter the physical or chemical state of the ices within its envelope. The derived abundances of these major species relative to H$_2$O significantly exceed the values typically observed toward other embedded protostars. Finally, we place the ice inventory of EC~53 in the context of other protostellar systems observed with JWST, highlighting that its chemically rich, thermally quiescent ice reservoir provides a benchmark for studying ice evolution under episodic accretion.
format Preprint
id arxiv_https___arxiv_org_abs_2604_08769
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle EPISODE IV: Ice Inventory in the Envelope of EC 53
Kim, Jaeyeong
Lee, Jeong-Eun
Kim, Chul-Hwan
Lee, Seokho
Baek, Giseon
Lee, Seonjae
Yang, Yao-Lun
Aikawa, Yuri
Herczeg, Gregory J.
Johnstone, Doug
Green, Joel D.
Jeong, Woong-Seob
Solar and Stellar Astrophysics
We present the 1.6$-$28 $μ$m spectra of the young protostar EC 53, obtained with JWST NIRSpec IFU and MIRI MRS during the quiescent and burst phases of its periodic brightness variations. To isolate ice absorption features, we modeled and removed the mid-infrared silicate dust absorption using a dedicated continuum-fitting procedure. In the optical depth spectrum, we first fit the broad H$_2$O ice features and then decomposed the major ice components, including NH$_3$, CO$_2$, CH$_3$OH, CO, and CH$_4$, by matching laboratory profiles for both pure and H$_2$O-mixed ices. The 4.62 $μ$m and 6.85 $μ$m bands are attributed to OCN$^-$ and NH$_4^+$ ions, respectively. Minor or tentative contributions from complex species (HCOOH, H$_2$CO, CH$_3$COOH, CH$_3$CHO, CH$_3$CH$_2$OH, and NH$_2$CHO) are also considered to our global ice analysis. The silicate-corrected spectra reveal no measurable change in any ice absorption band between the two phases, indicating that moderate and short-period accretion bursts in EC~53 do not significantly alter the physical or chemical state of the ices within its envelope. The derived abundances of these major species relative to H$_2$O significantly exceed the values typically observed toward other embedded protostars. Finally, we place the ice inventory of EC~53 in the context of other protostellar systems observed with JWST, highlighting that its chemically rich, thermally quiescent ice reservoir provides a benchmark for studying ice evolution under episodic accretion.
title EPISODE IV: Ice Inventory in the Envelope of EC 53
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2604.08769