Solid ¹²C/¹³C for various astronomical environments. The filled red, gray, and white stars represent the ratios derived from the ¹²CO₂ 15.2, 4.27, and 2.70 µm bands, respectively. We also include molecular clouds (Ice Age) (McClure et al. 2023) and a massive YSO (Infrared Space Observatory). (Boogert et al. 2000). The dashed purple line shows the solar abundance, and the dot-dashed gray line shows the local ISM ratio (Boogert et al. 2000). The small solid error bars of the JOYS+ data points illustrate when the band strengths were excluded from the error analysis. The faint and generally larger error bars of the JOYS+ data points illustrate the uncertainty, including the error on the band strength. Further details of the error analysis can be found in Appendix A.