Abrupt changes in spectral line profiles, polarization, brightness, and color on time scales of hours to days are sometimes observed in Be stars, although they cannot be considered common. Such outburst events bring to mind solar flares and coronal mass ejections, which are powered by the sudden release of large amounts of energy stored in the magnetic field near the surface of the Sun.
The difficulty with this analogy is that early-type stars are not expected to have substantial magnetic fields, because they lack the deep subsurface convection zone needed to maintain a magnetic field by dynamo action. Nevertheless, many observations continue to point to magnetism as an essential element of the Be phenomenon.
<Previous Topic] [Introduction] [Next Topic>