The methanol–methyl cyanide correlation: A chemical path from protostars to comets
8 affiliations
- 1INAF, Osservatorio Astrofisico di Arcetri
- 2NASA – Goddard Space Flight Center
- 3Catholic University of America
- 4School of Physics and Astronomy, University of Leeds
- 5Center for Astrophysics, Harvard & Smithsonian
- 6Observatoire de Paris, LESIA
- 7Univ. Grenoble Alpes
- 8American University
Abstract
Context. Comets are the frozen remnants of the early Solar System. By investigating their chemical composition, we can unveil the physical processes that shaped our planetary system and the evolution of interstellar material into planetary building blocks.
Aims. Systematic comparisons of the chemical composition of protostellar environments, disks, and comets remain rare and are often restricted to a narrow selection of targets. This study overcomes these limitations by employing a broader statistical approach that allowed us to identify inconsistencies in existing datasets. It thus provides a more comprehensive overview.
Methods. We present the first statistical analysis of methyl cyanide (CH ₃ CN) and methanol (CH ₃ OH) across a diverse and consistent sample, including 13 comets, 24 low-mass hot corinos, and seven planet-forming disks. We focused on the [CH ₃ CN]/[CH ₃ OH] abundance ratio, which is strongly correlated in hot corinos and might provide a sensitive diagnostic of the thermal and chemical evolution from interstellar clouds to planetary building blocks.
Results. While the [CH ₃ CN]/[CH ₃ OH] abundance ratios vary significantly within the planet-forming disk sample, this ratio is remarkably similar in comets and hot corinos. This indicates that despite material reprocessing, a consistent chemistry regulates the transition from protostellar envelopes to comets over time. Additionally, the correlation between CH ₃ CN and CH ₃ OH in comets appears to be weaker than in hot corinos, and it shows a potential dichotomy that might be related to different formation epochs, different formation regions in the disk, or post-formation thermal processing.
Conclusions. A statistical and multidisciplinary approach is essential to establish a robust baseline for characterizing the heterogeneity of planet-forming regions and comets. This helps us to identify differences and caveats that would remain hidden in single-source studies, with the risk of biasing the resulting conclusions. The expansion of these sample sizes will provide the statistical power needed to investigate the origins of our planetary system and other planetary systems.
Related
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS). VIII. First interstellar detection of fully deuterated methyl cyanide
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VIII. First interstellar detection of fully deuterated methyl cyanide
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) -- IV. Methyl cyanide isotopologues toward BHR71-IRS1
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VII. First interstellar detection of fully deuterated methanol
- Complex Organic Molecules in Protostars with ALMA Spectral Surveys (COMPASS) VI. Discovery of a class I methanol maser transition and its association with acetaldehyde
BibTeX
@article{lippi2026methanolmethyl,
title = {{The methanol–methyl cyanide correlation: A chemical path from protostars to comets}},
author = {M. Lippi and L. Podio and M. Cordiner and C. Codella and C. Walsh and A. S. Booth and N. Biver and D. Bockelée-Morvan and L. Giani and C. Ceccarelli and S. Faggi and G. L. Villanueva},
journal = {Astronomy \& Astrophysics},
year = {2026},
month = oct,
doi = {10.1051/0004-6361/202661354},
url = {https://www.aanda.org/10.1051/0004-6361/202661354},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The methanol–methyl cyanide correlation: A chemical path from protostars to comets
AU - M. Lippi
AU - L. Podio
AU - M. Cordiner
AU - C. Codella
AU - C. Walsh
AU - A. S. Booth
AU - N. Biver
AU - D. Bockelée-Morvan
AU - L. Giani
AU - C. Ceccarelli
AU - S. Faggi
AU - G. L. Villanueva
PY - 2026
DA - 2026/10/27
JO - Astronomy & Astrophysics
DO - 10.1051/0004-6361/202661354
UR - https://www.aanda.org/10.1051/0004-6361/202661354
AB - Context. Comets are the frozen remnants of the early Solar System. By investigating their chemical composition, we can unveil the physical processes that shaped our planetary system and the evolution of interstellar material into planetary building blocks. Aims. Systematic comparisons of the chemical composition of protostellar environments, disks, and comets remain rare and are often restricted to a narrow selection of targets. This study overcomes these limitations by employing a broader statistical approach that allowed us to identify inconsistencies in existing datasets. It thus provides a more comprehensive overview. Methods. We present the first statistical analysis of methyl cyanide (CH ₃ CN) and methanol (CH ₃ OH) across a diverse and consistent sample, including 13 comets, 24 low-mass hot corinos, and seven planet-forming disks. We focused on the [CH ₃ CN]/[CH ₃ OH] abundance ratio, which is strongly correlated in hot corinos and might provide a sensitive diagnostic of the thermal and chemical evolution from interstellar clouds to planetary building blocks. Results. While the [CH ₃ CN]/[CH ₃ OH] abundance ratios vary significantly within the planet-forming disk sample, this ratio is remarkably similar in comets and hot corinos. This indicates that despite material reprocessing, a consistent chemistry regulates the transition from protostellar envelopes to comets over time. Additionally, the correlation between CH ₃ CN and CH ₃ OH in comets appears to be weaker than in hot corinos, and it shows a potential dichotomy that might be related to different formation epochs, different formation regions in the disk, or post-formation thermal processing. Conclusions. A statistical and multidisciplinary approach is essential to establish a robust baseline for characterizing the heterogeneity of planet-forming regions and comets. This helps us to identify differences and caveats that would remain hidden in single-source studies, with the risk of biasing the resulting conclusions. The expansion of these sample sizes will provide the statistical power needed to investigate the origins of our planetary system and other planetary systems.
SN - 0004-6361
SN - 1432-0746
ER -