Astrobiologically Interesting Stars within 10 parsecs of the Sun

The existence of life based on carbon chemistry and water oceans relies upon planetary properties, chiefly climate stability, and stellar properties, such as mass, age, metallicity and Galactic orbits. The latter can be well constrained with present knowledge. We present a detailed, up-to-date compilation of the atmospheric parameters, chemical composition, multiplicity and degree of chromospheric activity for the astrobiologically interesting solar-type stars within 10 parsecs of the Sun. We determine their state of evolution, masses, ages and space velocities, and produce an optimized list of candidates that merit serious scientific consideration by the future space-based interferometry probes aimed at directly detecting Earth-sized extrasolar planets and seeking spectroscopic infrared biomarkers as evidence of photosynthetic life. The initially selected stars number 33 solar-type within the population of 182 stars (excluding late M-dwarfs) closer than 10 pc. A comprehensive and detailed data compilation for these objects is still essentially lacking: a considerable amount of recent data has so far gone unexplored in this context. We present 13 objects as the nearest "biostars", after eliminating multiple stars, young, chromospherically active, hard X-ray emitting stars, and low metallicity objects. Three of these "biostars", HD 1581, 109358 and 115617, closely reproduce most of the solar properties and are considered as premier targets. We show that approximately 7% of the nearby stars are optimally interesting targets for exobiology.Comment: 36 pages, recommended for publication in Astrobiolog

Ex-orbitant globality

Social theorists, drawing on the study of complex dynamical systems to address global processes, tend to evoke an immanent globality devoid of a constitutive otherness or outside. However, as well as dealing with the internal dynamics of systems, complexity studies point to the mutual implication of systems and their surroundings: a concern that resonates with the interest in the convolutions of the inside–outside relationship prominent in post-structural philosophies. This article, looking at theories about the dynamical characteristics of the solar system, galaxy and universe, develops the idea of an ex-orbitant globality that treats the earth as a system in active and ongoing interchange with its cosmic environment. A sense of the inevitable excess and unpredictability that attends this openness to the cosmos and to further other-than-human influences, it is suggested, has repercussions for the way we respond to environmental change injecting an element of abyssal undecidability into all our deliberations