Priestley, FD;
De Looze, I;
Barlow, MJ;
(2021)
The efficiency of grain growth in the diffuse interstellar medium.
Monthly Notices of the Royal Astronomical Society
10.1093/mnras/stab122.
(In press).
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Abstract
Grain growth by accretion of gas-phase metals is a common assumption in models of dust evolution, but in dense gas, where the timescale is short enough for accretion to be effective, material is accreted in the form of ice mantles rather than adding to the refractory grain mass. It has been suggested that negatively-charged small grains in the diffuse interstellar medium (ISM) can accrete efficiently due to the Coulomb attraction of positively-charged ions, avoiding this issue. We show that this inevitably results in the growth of the small-grain radii until they become positively charged, at which point further growth is effectively halted. The resulting gas-phase depletions under diffuse ISM conditions are significantly overestimated when a constant grain size distribution is assumed. While observed depletions can be reproduced by changing the initial size distribution or assuming highly efficient grain shattering, both options result in unrealistic levels of far-ultraviolet extinction. We suggest that the observed elemental depletions in the diffuse ISM are better explained by higher initial depletions, combined with inefficient dust destruction by supernovae at moderate (nH ∼ 30 cm−3) densities, rather than by higher accretion efficiences.
| Type: | Article |
|---|---|
| Title: | The efficiency of grain growth in the diffuse interstellar medium |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stab122 |
| Publisher version: | https://doi.org/10.1093/mnras/stab122 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | dust, extinction, ISM: evolution |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10120525 |
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