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Chemistry and kinematics of the pre-stellar core L1544: Constraints from H2D+

Floris van der Tak·Paola Caselli·Malcolm Walmsley·Cecilia Ceccarelli·Aurore Bacmann·Antonio Crapsi
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Abstract

This paper explores the sensitivity of line profiles of H2D+, HCO+ and N2H+, observed towards the center of L1544, to various kinematic and chemical parameters. The total width of the H2D+ line can be matched by a static model and by models invoking ambipolar diffusion and gravitational collapse. The derived turbulent line width is b=0.15 km/s for the static case and <~ 0.05 km/s for the collapse case. However, line profiles of HC18O+ and N2H+ rule out the static solution. The double-peaked H2D+ line shape requires either infall speeds in the center that are much higher than predicted by ambipolar diffusion models, or a shell-type distribution of H2D+, as is the case for HCO+ and N2H+. At an offset of ~20 arcsec from the dust peak, the H2D+ abundance drops by a factor of ~5.

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Floris van der Tak, Paola Caselli, Malcolm Walmsley, Cecilia Ceccarelli, Aurore Bacmann, Antonio Crapsi. 2003-11-05. Chemistry and kinematics of the pre-stellar core L1544: Constraints from H2D+. https://doi.org/10.1007/978-3-642-18902-9_97

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