Related papers: Interstellar Escape from Proxima b is Barely Possi…
Human space exploration and settlement of other planets is becoming increasingly technologically feasible, while mission concepts for remote and crewed missions to nearby star systems continue to be developed. But the long-term success of…
Proxima b is our nearest potentially rocky exoplanet and represents a formidable opportunity for exoplanet science and possibly astrobiology. With an angular separation of only 35~mas (or 0.05~AU) from its host star, Proxima b is however…
Proxima b is a planet with a minimum mass of 1.3 MEarth orbiting within the habitable zone (HZ) of Proxima Centauri, a very low-mass, active star and the Sun's closest neighbor. Here we investigate a number of factors related to the…
At a distance of about 4.22 lightyears, it would take about 100,000 years for humans to visit our closest stellar neighbor Proxima Centauri using modern chemical thrusters. New technologies are now being developed that involve high-power…
World ships are hypothetical, large, self-contained spacecraft for crewed interstellar travel, taking centuries to reach other stars. Due to their crewed nature, size, and long trip times, the feasibility of world ships faces an additional…
The Galactic habitable zone is defined as the region with highly enough metallicity to form planetary systems in which Earth-like planets could be born and might be capable of sustaining life surviving to the destructive effects of nearby…
It is often presumed, that life evolves relatively fast on planets with clement conditions, at least in its basic forms, and that extended periods of habitability are subsequently needed for the evolution of higher life forms. Many planets…
Properties of starburst-driven outflows in dwarf galaxies are compared to those in more massive galaxies. Over a factor of roughly 10 in galactic rotation speed, supershells are shown to lift warm ionized gas out of the disk at rates up to…
The primary difficulty with using transits to discover extrasolar planets is the low probability a planet has of transiting its parent star. One way of overcoming this difficulty is to search for transits in dense stellar fields, such as…
The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question as to whether the seven Earth-sized…
Planetary habitability is in part determined by the atmospheric evolution of a planet; one key component of such evolution is escape of heavy ions to space. Ion loss processes are sensitive to the plasma environment of the planet, dictated…
We model how repeated supernova explosions in high-redshift dwarf starburst galaxies drive superbubbles and winds out of the galaxies. We compute the efficiencies of metal and mass ejection and energy transport from the galactic potentials,…
Atmospheric escape is key to explaining the long-term evolution of planets in our Solar System and beyond, and in the interpretation of atmospheric measurements. Hydrodynamic escape is generally thought to be driven by the flux of extreme…
Ultraviolet radiation is a double-edged sword to life. If it is too strong, the terrestrial biological systems will be damaged. And if it is too weak, the synthesis of many biochemical compounds can not go along. We try to obtain the…
The circumstellar habitable zone and its various refinements serves as a useful entry point for discussing the potential for a planet to generate and sustain life. But little attention is paid to the quality of available energy in the form…
Nomadic worlds, i.e., objects not gravitationally bound to any star(s), are of great interest to planetary science and astrobiology. They have garnered attention recently due to constraints derived from microlensing surveys and the recent…
There is a longstanding discussion about whether low mass stars can form from pristine gas in the early Universe. A particular point of interest is whether we can find surviving pristine stars from the first generation in our local…
We re-examine the likelihood for alien civilizations to develop communication technology on the basis of the general assumption that life elsewhere could have a non-carbon chemical foundation. We particularized the discussion to a complex…
Dynamical considerations, presented herein via analytic scalings and numerical experiments, imply that Earth-mass planets accreting in regions that become habitable zones of M dwarf stars form within several million years. Temperatures in…
We assess how physically realistic the ''simulation hypothesis'' for this Universe is, based on physical constraints arising from the link between information and energy, and on known astrophysical constraints. We investigate three cases:…