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The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores

C. Vastel·P. Caselli·C. Ceccarelli·T. G. Phillips·M. Wiedner·R. peng·M. Houde·C. Dominik
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Abstract

Prestellar cores are unique laboratories for studies of the chemical and physical conditions preceding star formation. We observed the prestellar core L1544 in the fundamental transition of ortho-H2D+ (1_1,0-1_1,1) at different positions over 100", and found a strong correlation between its abundance and the CO depletion factor. We also present a tentative detection of the fundamental transition of para-D2H+ (1_1,0-1_0,1) at the dust emission peak. Maps in N2H+, N2D+, HCO+ and DCO+ are used, and interpreted with the aid of a spherically symmetric chemical model that predicts the column densities and abundances of these species as a function of radius. The correlation between the observed deuterium fractionation of H3+, N2H+ and HCO+ and the observed integrated CO depletion factor across the core can be reproduced by this chemical model. In addition a simpler model is used to study the H2D+ ortho-to-para ratio. We conclude that, in order to reproduce the observed ortho-H2D+ observations, the grain radius should be larger than 0.3 microns.

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C. Vastel, P. Caselli, C. Ceccarelli, T. G. Phillips, M. Wiedner, R. peng, M. Houde, C. Dominik. 2006-03-21. The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the Deuteration Factory in Prestellar Cores. https://doi.org/10.1086/504371

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