A new measurement method of isotopologue ratios in protoplanetary disks: a case study of the 12CO\/13CO ratio in the TW Hya disk<\/p>\n\n\n\n
speaker: Tomohiro Yoshida<\/p>\n\n\n\n
Abstract:<\/p>\n\n\n\n
Planetary systems are thought to be born in protoplanetary disks. Isotope ratios are a powerful\u00a0tool for investigating the material origin and evolution from molecular clouds to planetary systems via\u00a0protoplanetary disks. However, it is\u00a0challenging to measure the isotope (isotopologue) ratios, especially\u00a0in protoplanetary disks, because the emission lines of major species are saturated. We developed a new\u00a0method to overcome these challenges by using optically thin line\u00a0wings induced by thermal broadening.\u00a0As a first application of the method, we measured the\u00a012CO\/13CO ratio in the TW Hya protoplanetary disk. 12CO\/13CO was estimated to be ~23, which is\u00a0significantly smaller than the typical ISM value (~69)\u00a0in the inner disk.\u00a0In contrast, it is suggested that\u00a012CO\/13CO is higher than >100\u00a0in the outer disk. Our results imply that the gas-phase\u00a012CO\/13CO can vary by a\u00a0factor of >5\u00a0even inside a protoplanetary disk, and therefore, can be used to trace material evolution\u00a0in\u00a0disks.<\/p>\n","protected":false},"excerpt":{"rendered":"