X-ray/optical observations of stars with shallow convection zones ${\bf (A8{-}G2~V)}$

Observations of convection in A-type stars

Convection and turbulence in stellar atmospheres have a significant effect on the emergent flux from A-type stars. The recent theoretical advancements in convection modelling have proved a challenge to the observers to obtain measurements with sufficient precision and accuracy to allow discrimination between the various predictions. A discussion of the current observational techniques used to e...

The Interaction Of Multiple Convection Zones In A-type Stars

A-type stars have a complex internal structure with the possibility of multiple convection zones. If not sufficiently separated, such zones will interact through the convectively stable regions that lie between them. It is therefore of interest to ask whether the typical conditions that exist within such stars are such that these convection zones can ever be considered as disjoint. In this pape...

X-Ray Observations of Neutron Stars with XMM-Newton & Chandra

Interacting Convection Zones

We present results from simulations to examine how the separation between two convectively unstable layers affects their interaction. We show that two convectively ustable layers remain connected via the overshooting plumes even when they are separated by several pressure scale heights.

Plumes in stellar convection zones

All numerical simulations of compressible convection reveal the presence of strong downwards directed flows. Thanks to helioseismology, such plumes have now been detected also at the top of the solar convection zone, on supergranular scales. Their properties may be crudely described by adopting Taylor’s turbulent entrainment hypothesis, whose validity is well established under various condition...