It is shown here how new experimental data, for the electrical properties of solid CO, can be used to fill important gaps in our understanding of the evolution of pre-stellar cores. Dust grains with a mantle of CO lead to a reduction in the degree of ionization in these cores by a factor of between 5 and 6. The lifetimes for expulsion of magnetic fields from cores, a process generally necessary for gravitational collapse, are reduced from current estimates of several Myr, by a similar factor. This removes a major inconsistency, since lifetimes now tally with typical ages of pre-stellar cores of a few hundred thousand to one million years, derived from observations. With the reduced timescales, cores also escape disruption by Galactic supernova remnants. Our results provide a natural mechanism for the generation of so-called magnetically supercritical cores, in which the magnetic field alone cannot prevent gravitational collapse. In addition we find a minimum value for the density of pre-stellar cores of ≥1.1±0.1×104 H2 cm-3, in agreement with observations.
|Number of pages||6|
|Early online date||10 Nov 2016|
|Publication status||Published - 20 Nov 2016|
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Martin R. S. McCoustra
- School of Engineering & Physical Sciences, Institute of Chemical Sciences - Professor
- School of Engineering & Physical Sciences, Institute of Mechanical, Process & Energy Engineering - Professor
- School of Engineering & Physical Sciences - Professor
Person: Academic (Research & Teaching)