JWST Maps Interstellar Ice Composition Around Six Protostars in Orion A
Astronomers used the James Webb Space Telescope to create detailed maps of ice distribution and chemical composition around six Class 0 protostars in the Orion A molecular cloud. The study measured multiple ice species including water, carbon dioxide, and organic compounds at ~100 AU resolution, revealing significant variations in ice abundances. The findings suggest most interstellar ice forms during the prestellar stage and is inherited by protostars, with implications for understanding star and planet formation chemistry.
Researchers analyzed high-resolution spectroscopic data from JWST's NIRspec and MIRI MRS instruments to construct pixel-by-pixel absorption maps of six Class 0 protostars (HOPS-56, HOPS-60, HOPS-73, HOPS-91, HOPS-96, and HOPS-108) in Orion A. They measured column densities of key ice species including H₂O, CO₂, CO, OCN⁻, NH₄⁺, H₂CO, CH₄, and OCS by fitting observed spectra with laboratory ice analogs and employing radiative transfer modeling. The analysis revealed significant spatial variations in ice abundances and distributions, with evidence of protostellar heating and outflows affecting ice mantles, particularly in HOPS-60. The total ice composition accounts for approximately 90% of the observed ice inventory and is consistent with astrochemical models. The sources segregated into two distinct groups based on abundance ratios relative to water, possibly reflecting evolutionary differences or variations in envelope physical conditions.
What's missing
The study does not discuss implications for volatile delivery to forming planetary systems or how these ice inventories compare to other star-forming regions beyond Orion A. The paper does not address potential limitations in the laboratory ice analogs used for spectral fitting or uncertainties in the radiative transfer modeling.
What different sources said
- arXiv astro-phCenter
The Colors of Ices: Measuring ice column density through photometry
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