1,5,8,11,2,- 1University of Virginia, Department of Chemistry, Charlottesville, VA, USA
- 2Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
- 3Department of Physics, Catholic University of America, Washington, DC, USA
- 4Department of Physics, American University, Washington, DC, USA
- 5National Radio Astronomy Observatory, Charlottesville, VA, USA
- 6LIRA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris Cité, Meudon, France
- 7IRAM, Saint Martin d'Hères, France
- 8Physikalish-Meteorologisches Observatorium Davos und Weltstrahlungszentrum (PMOD/WRC), Davos Dorf, Switzerland
- 9RIKEN Pioneering Research Institute, Wako-shi, Japan
- 10Center of Astronomy and Gravitation, and Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan, ROC
- 11NAF - Osservatorio astrofisico di Arcetri, Florence, Italy
- 12Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
- 13Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh, UK
- 14Institute for Astrophysical Research, Boston University, Boston, MA, USA
- 15Atacama Large Millimeter Array, Chile
Determining isotopic ratios in cometary comae can be a useful characteristic in investigating the evolutional history of the chemical complexity of our Solar System. Carbon isotope fractionation has been measured in several comets for small molecules, such as C2, CN, and HCN, but larger molecules require either direct in situ observations or a very bright comet. In April of 2024, comet 12P/Pons-Brooks, a Halley-type comet and one of the brightest periodic comets, was targeted with a multi-facility observing campaign. This work focuses on Band 6 measurements made with the Atacama Large Millimeter/submillimeter Array of 12CH3OH and the first remote detection of 13CH3OH in a comet. Spectral modeling was carried out using the SUBLIME non-LTE radiative transfer code and an overall carbon isotopic ratio was determined. I will present the results of the modeling and discuss how this ratio compares to 12C/13C ratios derived from other comets and source types. These findings can contextualize recent measurements of the carbon isotopic ratio in protostars and protoplanetary disks which indicate unexpected 13C enrichment.
How to cite: Foster, K., Cordiner, M., Roth, N., Remijan, A., Biver, N., Bockelée-Morvan, D., Boissier, J., Bonev, B., Charnley, S., Crovisier, J., Drozdovskaya, M., Furuya, K., Jin, M., Kuan, Y.-J., Lippi, M., Lis, D., Milam, S., Opitom, C., Qi, C., and Simon, R.: Carbon isotope fractionation of CH3OH in Comet 12P/Pons-Brooks, Europlanet Science Congress 2026, The Hague, The Netherlands, 7–11 Sep 2026, EPSC2026-576, https://doi.org/10.5194/epsc2026-576, 2026.
