[Normal Stars and WD -- Invited ]
X-ray emission processes in stars and their immediate environment
Paola Testa, Harvard-Smithsonian Center for Astrophysics
A decade of X-ray stellar observations with Chandra and
XMM-Newton has led to significant advances in our understanding of the
physical processes at work in hot (magnetized) plasmas in stars and
their immediate environment, providing new perspectives and challenges,
and in turn the need for improved models.The wealth of high-quality stellar spectra has allowed us to investigate,
in detail, the characteristics of the X-ray emission across the HR
diagram. Progress has been made in addressing issues ranging from
classical stellar activity in stars with solar-like dynamos (such as,
flares, activity cycles, spatial and thermal structuring of the X-ray
emitting plasma, evolution of X-ray activity with age,...), to X-ray
generating processes (e.g. accretion, jets, magnetically confined
winds,..) that were poorly understood in the pre-Chandra/XMM-Newton era.
I will discuss the progress made in the study of high energy stellar
physics and its impact in a wider astrophysics context, focusing on the
role of spectral diagnostics now accessible.