Observable Effects of B fields on the Winds and Envelopes of Hot Stars

Abstract

Magnetic fields on hot stars can produce a variety of interesting effects on the velocity, density, and temperature structure in the winds from the stars. The fields can produce a longitudinal dependence of the mass flux, which would lead to cyclical variability such as that seen in optical and UV spectra of many early-type stars. The fields can channel and spin-up the outflow, which appears to be needed to explain the disk-like density enhancements around Ap and Be stars. Magnetic confinement of hot gases can occur and be responsible for the anomalously high EUV fluxes seen in B giants, and the anomalous high ion X-ray line emission that is seen in recent CHANDRA observations. Special attention is given to the reports at this meeting that A stars develop magnetic Ap phenomenon only after about 30 percent of their main sequence lifetimes. A similar delay occurs for the emission line Be stars. It is suggested that these delays are related to the time it takes for fields to rise through the sub-adiabatic envelope to the surface starting from the interface between the convective-core and radiative-envelope where they are generated.