Conductive Evaporation of the Local Interstellar Cloud at the Hot Bubble Interface

A warm cloud embedded in million-degree gas is heated at its surface by electron conduction, and the heated layer flows away: the cloud evaporates. Applying the classical conduction-front mass-loss formula to a cloud of radius two parsecs facing the Local Bubble interior gives a mass-loss rate of 8.8e-07 solar masses per year and an evaporation time of only 0.4 million years for a cloud of 0.35 solar masses. That time is far shorter than the age of the bubble, so classical unmagnetised conduction would have destroyed the local clouds long ago. Their observed survival is therefore quantitative evidence that conduction at the interface is suppressed, by the factor of at least a few tens that a magnetic field draped over the cloud surface provides. The discrepancy is the result: it measures the suppression the interface must have. The rate is computed from stated published inputs with the deposited script, not measured.