Related papers: The Sun and stars as the primary energy input in p…
The current progress in the detection of terrestrial type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions.…
Stars are powerful sources for weakly interacting particles that are produced by nuclear or plasma processes in their hot interior. These fluxes can be used for direct measurements (e.g. solar or supernova neutrinos) or the back-reaction on…
The magnetic activity of a star -- which modulates the stellar wind outflow -- shapes the immediate environments of orbiting planets and induces atmospheric loss thereby impacting their habitability. We perform a detailed parameter space…
Dynamical evolution plays a key role in shaping the current properties of star clusters and star cluster systems. A detailed understanding of the effects of evolutionary processes is essential to be able to disentangle the properties which…
Stellar activity has a particularly strong influence on planets at small orbital distances, such as close-in exoplanets. For such planets, we present two extreme cases of stellar variability, namely stellar coronal mass ejections and…
Stellar flares, winds and coronal mass ejections form the space weather. They are signatures of the magnetic activity of cool stars and, since activity varies with age, mass and rotation, the space weather that extra-solar planets…
Earth's atmosphere has evolved as volatile species cycle between the atmosphere, ocean, biomass and the solid Earth. The geochemical, biological and astrophysical processes that control atmospheric evolution are reviewed from an "Earth…
Stellar flares present challenges to the potential habitability of terrestrial planets orbiting M dwarf stars through inducing changes in the atmospheric composition and irradiating the planet's surface in large amounts of ultraviolet…
We study the impact of multi-layered clouds (low-level water and high-level ice clouds) on the thermal emission spectra of Earth-like planets orbiting different types of stars. Clouds have an important influence on such planetary emission…
The Sun is the closest star to our planet and it is the most studied, perhaps, there exist too much procesess not-understood. One of the solar processes that have a direct interaction with the earth is the solar wind. The solar wind is…
Massive stars are the drivers of star formation and galactic dynamics due to their relatively short lives and explosive demises, thus impacting all of astrophysics. Since they are so impactful on their environments, through their winds on…
The key to understanding an extrasolar giant planet's spectrum--and hence its detectability and evolution--lies with its atmosphere. Now that direct observations of thermal emission from extrasolar giant planets are in hand, atmosphere…
Mass is the most important stellar parameter, but it is not directly observable for a single star. Spherical model stellar atmospheres are explicitly characterized by their luminosity ($L_\star$), mass ($M_\star$) and radius ($R_\star$),…
Convection is the most important physical process that determines the structure of the envelopes of cool stars. It influences the surface radiation flux and the shape of observed spectral line profiles and is responsible for both generating…
The Sun and sun-like stars commonly host the multi-million-Kelvin coronae and the 10,000-Kelvin chromospheres. These extremely hot gases generate X-ray and Extreme Ultraviolet emissions that may impact the erosion and chemistry of…
Rotation has a number of important effects on the evolution of stars. Apart from structural changes because of the centrifugal force, turbulent mixing and meridional circulation caused by rotation can dramatically affect a star's chemical…
Cloud environment is thought to play a critical role in determining the mechanism of formation of massive stars. In this contribution we review the physical characteristics of the environment around recently formed massive stars. Particular…
The chemical enrichment of the Universe; the mass spectrum of planetary nebulae, white dwarfs and gravitational wave progenitors; the frequency distribution of Type I and II supernovae; the fate of exoplanets ... a multitude of phenomena…
Mass loss is a determinant factor which strongly affects the evolution and the fate of massive stars. At low metallicity, stars are supposed to rotate faster than at the solar one. This favors the existence of stars near the critical…
The formation of stars is a key process in astrophysics. Detailed knowledge of the physical mechanisms that govern stellar birth is a prerequisite for understanding the formation and evolution of our galactic home, the Milky Way. A theory…