Can cool flames support candle flame burning in microgravity?

This communication asks the question whether the microgravity candle flames reported in previous work may have burned briefly with a cool flame after hot-flame extinction. The question follows the discovery of cool-flame supported droplet combustion during experiments on the International Space Station (ISS). While there is no direct evidence to either confirm or refute cool-flame supported candle burning there is indirect evidence that suggests cool-flame supported candle burning might have occurred. Images of the illuminated candle following hot-flame extinction show a spherical aerosol cloud that is similar in size, shape and character to the aerosol cloud surrounding a droplet during and following cool-flame burning in the ISS droplet combustion experiments. This work further presents the rationale for that assertion. Published by Elsevier Inc. on behalf of The Combustion Institute.