Séminaire IPAG

---

Special seminar: Carbon isotope chemistry in protoplanetary disks: possible links to Ryugu samples

jeudi 7 décembre 2023 - 11h00

Hideko Nomura - NAOJ
--- 
Isotopic ratios provide a powerful tool for understanding the origins of materials. Thanks to recent ALMA observations with high sensitivity and high spatial resolution, complex organic molecules as well as many rare isotopologues have been newly detected towards protoplanetary disks. Recent ALMA observations suggest bimodal fractionation of carbon isotopes in CO and HCN molecules; 12CO/13CO ratio shows a lower value (~20) while H12CN/H13CN does higher value (~ 86) inside ~100 au of the TW Hya disk, compared with the local ISM value (~69), which could be caused by thermal isotope exchange reaction under a low temperature environment with C/O > 1. In addition, more recent our work shows the observed carbon isotope ratio of CN is close to the ISM value (~70). We also performed chemical reaction network calculations with carbon isotopes in the disk, which suggest possible carbon and oxygen depletion with preferential 12C depletion from gas-phase to ices on grains to explain the observations. Finally, I will briefly discuss a possible link to the materials taken by the Japanese Hayabusa 2 sample return mission exploring to the asteroid Ryugu.

---

Hôtes : Pierre Hily-Blant

Salle Manuel Forestini, 414 rue de la piscine, 38400 Saint Martin d'Hères