The Isotopic Links from Planet Forming Regions to the Solar System

Abstract

Isotopic ratios provide a powerful tool for understanding the origins of materials, including the volatile and refractory matter within solar system bodies. Recent high sensitivity observations of molecular isotopologues, in particular with ALMA, have brought us new information on isotopic ratios of hydrogen, carbon, nitrogen and oxygen in star and planet forming regions as well as the solar system objects. Solar system exploration missions, such as Rosetta and Cassini, have given us further new insights. Meanwhile, the recent development of sophisticated models for isotope chemistry including detailed gas-phase and grain surface reaction network has made it possible to discuss how isotope fractionation in star and planet forming regions is imprinted into the icy mantles of dust grains, preserving a record of the initial isotopic state of solar system materials. This chapter reviews recent progress in observations of molecular isotopologues in extra-solar planet forming regions, prestellar/protostellar cores and protoplanetary disks, as well as objects in our solar system -comets, meteorites, and planetary/satellite atmospheres -and discusses their connection by means of isotope chemical models.

First detection of CHD2OH towards pre-stellar cores

“…Since deuteration fractionation depends heavily on the physical and chemical parameters of the cores, it is critical to verify whether the observed D/H ratios of the dense cores are legacies from the preceding evolutionary stages and remain as fossil records, and how they differ from those in comets and meteorites of the Solar System et al 2014;Nomura et al 2022). These questions can be answered by examining the variations of D/H ratios in dense cores prior to star formation.…”

Complex Organic Molecules Detected in 12 High-mass Star-forming Regions with Atacama Large Millimeter/submillimeter Array

“…We note that the levels of fractionation are much higher than the Galactic (Wilson & Rood 1994) and local interstellar medium (ISM) values (0.015 for 13 C/ 12 C; 0.0036 for 15 N/ 14 N; 0.0018 for 18 O/ 16 O; Nomura et al 2022). As we observed the interior region close to the massive protostar, these unusually high isotopic ratios may come from significantly different physical and chemical conditions deviating from the Galacticscale environment.…”

“…As we observed the interior region close to the massive protostar, these unusually high isotopic ratios may come from significantly different physical and chemical conditions deviating from the Galacticscale environment. In addition, the isotope fractionations differ by species, but the values adopted for the Galactic and local ISM ratios are derived from atoms, and thus they could be very different from the ratios in the COMs (e.g., Nomura et al 2022;Drozdovskaya et al 2022).…”

Complex organic molecules detected in twelve high-mass star-forming regions with Atacama Large Millimeter/submillimeter Array (ALMA)

“…We note that the levels of fractionation are much higher than the Galactic (Wilson & Rood 1994) and local interstellar medium (ISM) values (0.015 for 13 C/ 12 C; 0.0036 for 15 N/ 14 N; 0.0018 for 18 O/ 16 O; Nomura et al 2022). Since we observed interior region, close to the massive protostar, these unusually high isotopic ratios may come from significantly different physical and chemical conditions deviated from the Galactic scale environment.…”

“…Since we observed interior region, close to the massive protostar, these unusually high isotopic ratios may come from significantly different physical and chemical conditions deviated from the Galactic scale environment. In addition, the isotope fractionations differ by species, but the values adopted for the Galactic and local ISM ratios are derived from atoms, and thus, they could be very different from the ratios in COMs (e.g., Nomura et al 2022;Drozdovskaya et al 2022).…”