Browsing by Author "Jorgensen, J. K."

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    Linking ice and gas in the Coronet cluster in Corona Australis
    (2023) Perotti, G.; Jorgensen, J. K.; Rocha, W. R. M.; Plunkett, A.; Artur de la Villarmois, E.; Kristensen, L. E.; Sewilo, M.; Bjerkeli, P.; Fraser, H. J.; Charnley, S. B.
    Context. During the journey from the cloud to the disc, the chemical composition of the protostellar envelope material can be either preserved or processed to varying degrees depending on the surrounding physical environment.Aims. This works aims to constrain the interplay of solid (ice) and gaseous methanol (CH3OH) in the outer regions of protostellar envelopes located in the Coronet cluster in Corona Australis (CrA), and assess the importance of irradiation by the Herbig Ae/Be star R CrA. CH3OH is a prime test case as it predominantly forms as a consequence of the solid-gas interplay (hydrogenation of condensed CO molecules onto the grain surfaces) and it plays an important role in future complex molecular processing.Methods. We present 1.3 mm Submillimeter Array (SMA) and Atacama Pathfinder Experiment (APEX) observations towards the envelopes of four low-mass protostars in the Coronet cluster. Eighteen molecular transitions of seven species were identified. We calculated CH3OH gas-to-ice ratios in this strongly irradiated cluster and compared them with ratios determined towards protostars located in less irradiated regions such as Serpens SVS 4 in Serpens Main and the Barnard 35A cloud in the lambda Orionis region. Results. The CH3OH gas-to-ice ratios in the Coronet cluster vary by one order of magnitude (from 1.2 x 10(-4) to 3.1 x 10(-3)) which is similar to less irradiated regions as found in previous studies. We find that the CH3OH gas-to-ice ratios estimated in these three regions are remarkably similar despite the different UV radiation field intensities and formation histories.Conclusions. This result suggests that the overall CH3OH chemistry in the outer regions of low-mass envelopes is relatively independent of variations in the physical conditions and hence that it is set during the prestellar stage.
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    Physical properties of accretion shocks toward the Class I protostellar system Oph-IRS 44
    (2022) de la Villarmois, E. Artur; Guzman, V. V.; Jorgensen, J. K.; Kristensen, L. E.; Bergin, E. A.; Harsono, D.; Sakai, N.; van Dishoeck, E. F.; Yamamoto, S.
    Context. The final outcome and chemical composition of a planetary system depend on its formation history: the physical processes that were involved and the molecular species available at different stages. Physical processes such as accretion shocks are thought to be common in the protostellar phase, where the envelope component is still present, and they can release molecules from the dust to the gas phase, altering the original chemical composition of the disk. Consequently, the study of accretion shocks is essential for a better understanding of the physical processes at disk scales and their chemical output.