Theories explaining the continual expansion of the outer atmospheric layers of luminous
early-and late-type stars are reviewed. The radiative, coronal, and hybrid stellar-wind …

Optical and UV spectroscopic diagnostics which provide constraints on theoretical models of
mass-loss and mass motions in cool-star atmospheres are discussed. The use of X-ray and …

The basic mechanisms responsible for producing winds from cool, late-type stars are still
largely unknown. We take inspiration from recent progress in understanding solar wind …

Mass-loss of red giant branch (RGB) stars is still poorly determined, despite its crucial role in
the chemical enrichment of galaxies. Thanks to the recent detection of solar-like oscillations …

Context. The second parameter (the first being metallicity) defining the distribution of stars
on the horizontal branch (HB) of globular clusters (GCs) has long been one of the major …

We present 120 mÅ resolution spectra of the cores and wings of the Ca II H and K lines in 43
stars covering a wide range of spectral type and luminosity class. These spectra were …

Important progress in our understanding of stellar chromospheres has occurred in the past
few years as a result of new observations, developments in spectral line formation theory …

Globular star clusters are among the first stellar populations to have formed in the Milky Way,
and thus only a small sliver of their initial spectrum of stellar types are still burning hydrogen …

No part of the Hertzsprung-Russell diagram shows a more pronounced diversity of stellar
types than the upper part, which contains the most luminous stars. Can one visualize a …

Using the Spitzer IRAC camera we have obtained mid-IR photometry of the red giant branch
stars in the Galactic globular cluster 47 Tuc. About 100 stars show an excess of mid-IR light …