JOYS+ Study Of Solid State 12C/13C Isotope Ratios In Protostellar Envelopes: Observations of CO and CO2 Ice with JWST

The carbon isotope ratio is a powerful tool for studying the evolution of stellar systems. Recent detections of CO isotopologues in disks and exoplanet atmospheres pointed towards significant fractionation in these systems.

In order to understand the evolution of this quantity, it is crucial to trace the isotope abundance from stellar nurseries to planetary systems. During the protostellar stage the multiple vibrational modes of CO₂ and CO ice provide a unique opportunity to examine the carbon isotope ratio in the solid state.

Now with the sensitivity of the James Webb Space Telescope, these absorption features have become accessible at high S/N in Solar-mass systems. We quantify the ¹²CO₂/¹³CO₂ and the ¹²CO/¹³CO isotope ratios in 17 class 0/I low mass protostars from the ¹²CO₂ combination modes (2.70 μm and 2.77 μm), the ¹²CO₂ stretching mode (4.27 μm), the ¹³CO₂ stretching mode (4.39 μm), the ¹²CO₂ bending mode (15.2 μm), the ¹²CO stretching mode (4.67 μm) and the ¹³CO stretching mode (4.78 μm) using JWST observations. We also report a detection of the ¹²CO overtone mode at 2.35 μm.

The ¹²CO₂/¹³CO₂ ratios are in agreement and we find mean ratios of 85 ± 23, 76 ± 12 and 97 ± 17 for the 2.70 μm, 4.27 μm and the 15.2 μm bands, respectively. The main source of uncertainty stem from the error on the band strengths. The ¹²CO/¹³CO ratios derived from the 4.67 μm bands are consistent, albeit elevated with respect to the ¹²CO₂/¹³CO₂ ratios and we find a mean ratio of 165 ± 52.

These findings indicate that ices leave the pre-stellar stage with elevated carbon isotope ratios relative to the interstellar medium and that fractionation becomes significant during the later stages.

Full NIRSpec and MIRI spectra for EDJ183-b and Per-emb35. The the ice absorption features are shaded in color. The bottom panels show zoomed-in sections of the spectra. — astro-ph.SR

N. G. C. Brunken, E. F. van Dishoeck, K. Slavicinska, V. J. M. le Gouellec, W. R. M. Rocha, L. Francis, L. Tychoniec, M. L. van Gelder, M. G. Navarro, A. C. A. Boogert, P. J. Kavanagh, P. Nazari, T. Greene, M. E. Ressler, L. Majumdar

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2409.17237 [astro-ph.SR] (or arXiv:2409.17237v1 [astro-ph.SR] for this version)
https://doi.org/10.48550/arXiv.2409.17237
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Submission history
From: Nashanty Brunken
[v1] Wed, 25 Sep 2024 18:00:03 UTC (12,485 KB)
https://arxiv.org/abs/2409.17237

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