Abstract
With the discovery of hundreds of exoplanets and a potentially huge number of
Earth-like planets waiting to be discovered, the conditions for their
habitability have become a focal point in exoplanetary research. The classical
picture of habitable zones primarily relies on the stellar flux allowing liquid
water to exist on the surface of an Earth-like planet with a suitable
atmosphere. However, numerous further stellar and planetary properties
constrain habitability. Apart from "geophysical" processes depending on the
internal structure and composition of a planet, a complex array of
astrophysical factors additionally determine habitability. Among these,
variable stellar UV, EUV, and X-ray radiation, stellar and interplanetary
magnetic fields, ionized winds, and energetic particles control the
constitution of upper planetary atmospheres and their physical and chemical
evolution. Short- and long-term stellar variability necessitates full
time-dependent studies to understand planetary habitability at any point in
time. Furthermore, dynamical effects in planetary systems and transport of
water to Earth-like planets set fundamentally important constraints. We will
review these astrophysical conditions for habitability under the crucial
aspects of the long-term evolution of stellar properties, the consequent
extreme conditions in the early evolutionary phase of planetary systems, and
the important interplay between properties of the host star and its planets.
Users
Please
log in to take part in the discussion (add own reviews or comments).