Water deuteration toward embedded low- mass protostars: A physical and chemical diagnostic of the ear
| Main Author: | Sigersen Jensen, Sigurd |
|---|---|
| Format: | Proceeding poster |
| Terbitan: |
, 2019
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| Online Access: |
https://zenodo.org/record/3585451 |
Daftar Isi:
- Understanding the evolution of water during star formation, from the molecular cloud down to the protoplanetary disk, is a central goal of astrochemistry. Open questions on this topic include when and where water is formed and how the water content is influenced by the local environment in which the protostar is formed. The formation of water and its deuterated isotopologues, such as HDO, depends strongly on the physical conditions, i.e. temperature and density, in the protostars natal environment. The HDO/H2O ratio is thus a powerful tracer for both the physical and chemical evolution of water during the star formation process. I here present measurements of the deuterium fractionation of water (HDO/H2O) toward young embedded low-mass protostars utilizing some of the first ALMA band 5 observations of H2-18-O along with band 6 observations of HDO toward three isolated cores harboring young Class 0 protostars. These sources provide an excellent opportunity to study if and how the deuterium fractionation of water is influenced by the local cloud environment, i.e. how the density, temperature, and turbulence influence the water chemistry. The derived HDO/H2O ratios for the isolated protostars are significantly above the ratios previously derived for clustered Class 0 protostars (1700-2200 ppm vs 520-920 ppm), suggesting a clear difference in water deuteration depending on the local cloud environment in which the protostars originate. The observed difference in water deuteration between isolated and clustered protostars can be understood in the framework of recent numerical models of water formation and evolution during star formation and provide strong evidence for a significant chemical differentiation between stars in different cloud environments. This chemical differentiation likely extends to complex organic molecules and may impact the initial conditions in the protoplanetary system profoundly.