相关论文: Constraints in the coupling Star-Life
In a multiverse context, determining the probability of being in our particular universe depends on estimating its overall habitability compared to other universes with different values of the fundamental constants. One of the most…
Life is a complex biological phenomenon represented by numerous chemical, physical and biological processes performed by a biothermodynamic system/cell/organism. Both living organisms and inanimate objects are subject to aging, a biological…
The physical processes that determine the properties of our everyday world, and of the wider cosmos, are determined by some key numbers: the 'constants' of micro-physics and the parameters that describe the expanding universe in which we…
The magnetic activity of the Sun becomes stronger and weaker over roughly an 11 year cycle, modulating the radiation and charged particle environment experienced by the Earth as "space weather". Decades of observations from the Mount Wilson…
The activity of the Sun as a result of cyclic changes of the global magnetic field is studied. As a consequence of the analysis of magnetic activity of solar-type stars the following power dependencies were found: the dependence between the…
A habitable zone of a star is defined as a range of orbits within which a rocky planet can support liquid water on its surface. The most intriguing question driving the search for habitable planets is whether they host life. But is the age…
The ease of interstellar rocket travel is an issue with implications for the long term fate of our own and other civilizations and for the much-debated number of technological civilizations in the Galaxy. We show that the physical barrier…
This paper develops constraints on the values of the fundamental constants that allow universes to be habitable. We focus on the fine structure constant $\alpha$ and the gravitational structure constant $\alpha_G$, and find the region in…
Approximately one billion years (Gyr) in the future, as the Sun brightens, Earth's carbonate-silicate cycle is expected to drive CO$_2$ below the minimum level required by vascular land plants, eliminating most macroscopic land life. Here,…
The physics of stars, their workings and their evolution, is a goldmine of problems in statistical mechanics and thermodynamics. We discuss many examples that illustrate the possibility of deepening student's knowledge of statistical…
The mean surface temperature on Earth and other planets with atmospheres is determined by the radiative balance between the non-reflected incoming solar radiation and the outgoing long-wave black-body radiation from the atmosphere. The…
It is shown that the interaction of the electromagnetic field with the vacuum of the electron-positron field gives rise to dependence of the speed of light propagation on the radiation temperature. Estimation show that in the modern epoch,…
This activity has been developed as a resource for the "EU Space Awareness" educational programme. As part of the suite "Our Fragile Planet" together with the "Climate Box" it addresses aspects of weather phenomena, the Earth's climate and…
The near-star environment around young stars is very dynamic with winds, disks, and outflows. These processes are involved in star and planet formation, and influence the formation and habitability of planets around host stars. Even for the…
Stars play a decisive role in our Universe, from its beginning throughout its complete evolution. For a thorough understanding of their properties, evolution, and physics of their outer envelopes, stellar spectra need to be analyzed by…
In a previous study published in Astrobiology, we focused on the evolution of habitability of a 10 M_E super-Earth planet orbiting a star akin to the Sun. This study was based on a concept of planetary habitability in accordance to the…
Stars can produce steady-state winds through radiative driving as long as the mechanical luminosity of the wind does not exceed the radiative luminosity at its base. This upper bound on the mass loss rate is known as the photon-tiring…
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…
The driving force behind the origin and evolution of life has been the thermodynamic imperative of increasing the entropy production of the biosphere through increasing the global solar photon dissipation rate. In the upper atmosphere of…
Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature to explore…