Evolutionary Demographics of Molecular Ice Mantles in Young Stars with SPHEREx
Abstract
Molecular ices are a primary reservoir of volatile C, O, and N in star-forming environments, tracing the chemical pathway from molecular clouds to planet-forming disks. SPHEREx provides contiguous 0.75--5~μm all-sky spectrophotometry for vastly larger samples than are accessible to JWST, enabling population-scale ice demographics for the first time. We present a search for ice signatures in SPHEREx spectra of 20{,}292 young stellar objects (age <20~Myr) drawn from the Gaia-based kinematic catalog of Kounkel \& Covey 2019. Using laboratory templates for the spectral signatures of H2O (3.05~μm), CO2 (4.27~μm), and CO (4.67~μm), we identify 746 H2O ice candidates, including 131 high-confidence H2O+CO2 detections and 22 with additional corroborating CO absorption. When binning by age, we find that the H2O+CO2 detection rate declines by an order of magnitude between ≲3~Myr and ∼5~Myr, suggesting a chemical or physical evolutionary trend. Candidates concentrate toward high-extinction sightlines (AG ≳ 2.5~mag) and embedded SED morphologies, consistent with the idea of envelope dispersal and photodesorption depleting detectable ice mantles within the first few million years of pre-main-sequence evolution. This catalog provides a homogeneous demographic baseline and a prioritized target list for JWST follow-up.
Related
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BibTeX
@misc{serna2026evolutionary,
title = {{Evolutionary Demographics of Molecular Ice Mantles in Young Stars with SPHEREx}},
author = {J. Serna and S. P. Matt and M. McClure and M. Kounkel and C. G. Roman-Zuñiga},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38043},
eprint = {2610.38043},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38043},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Evolutionary Demographics of Molecular Ice Mantles in Young Stars with SPHEREx
AU - J. Serna
AU - S. P. Matt
AU - M. McClure
AU - M. Kounkel
AU - C. G. Roman-Zuñiga
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.38043
UR - https://arxiv.org/abs/2610.38043
AB - Molecular ices are a primary reservoir of volatile C, O, and N in star-forming environments, tracing the chemical pathway from molecular clouds to planet-forming disks. SPHEREx provides contiguous 0.75--5~μm all-sky spectrophotometry for vastly larger samples than are accessible to JWST, enabling population-scale ice demographics for the first time. We present a search for ice signatures in SPHEREx spectra of 20{,}292 young stellar objects (age <20~Myr) drawn from the Gaia-based kinematic catalog of Kounkel \& Covey 2019. Using laboratory templates for the spectral signatures of H_2O (3.05~μm), CO_2 (4.27~μm), and CO (4.67~μm), we identify 746 H_2O ice candidates, including 131 high-confidence H_2O+CO_2 detections and 22 with additional corroborating CO absorption. When binning by age, we find that the H_2O+CO_2 detection rate declines by an order of magnitude between ≲3~Myr and ∼5~Myr, suggesting a chemical or physical evolutionary trend. Candidates concentrate toward high-extinction sightlines (A_G ≳ 2.5~mag) and embedded SED morphologies, consistent with the idea of envelope dispersal and photodesorption depleting detectable ice mantles within the first few million years of pre-main-sequence evolution. This catalog provides a homogeneous demographic baseline and a prioritized target list for JWST follow-up.
ER -