Swansong biospheres: refuges for life and novel microbial biospheres on terrestrial planets near the end of their habitable lifetimes

2012 ◽  
Vol 12 (2) ◽  
pp. 99-112 ◽  
Author(s):  
Jack T. O'Malley-James ◽  
Jane S. Greaves ◽  
John A. Raven ◽  
Charles S. Cockell
Keyword(s):  
Climate Model ◽  
Cold Trap ◽  
Sequence Evolution ◽  
Form Of Life ◽  
Earth Like Planets ◽  
Forms Of Life ◽  
Complex Forms ◽  
End Stage ◽  
Micro Organisms ◽  
Host Stars

AbstractThe future biosphere on Earth (as with its past) will be made up predominantly of unicellular micro-organisms. Unicellular life was probably present for at least 2.5 Gyr before multicellular life appeared and will likely be the only form of life capable of surviving on the planet in the far future, when the ageing Sun causes environmental conditions to become more hostile to more complex forms of life. Therefore, it is statistically more likely that habitable Earth-like exoplanets we discover will be at a stage in their habitable lifetime more conducive to supporting unicellular, rather than multicellular life. The end stage of habitability on Earth is the focus of this work. A simple, latitude-based climate model incorporating eccentricity and obliquity variations is used as a guide to the temperature evolution of the Earth over the next 3 Gyr. This allows inferences to be made about potential refuges for life, particularly in mountains and cold-trap (ice) caves and what forms of life could live in these environments. Results suggest that in high latitude regions, unicellular life could persist for up to 2.8 Gyr from present. This begins to answer the question of how the habitability of Earth will evolve at local scales alongside the Sun's main sequence evolution and, by extension, how the habitability of Earth-like planets would evolve over time with their own host stars.

scholarly journals Search for stellar companions of exoplanet host stars by exploring the second ESA-Gaia data release

2019 ◽  
Vol 490 (4) ◽  
pp. 5088-5102 ◽  
Author(s):  
M Mugrauer
Keyword(s):  
Main Sequence ◽  
Stellar Systems ◽  
Sequence Evolution ◽  
The Sun ◽  
M Dwarfs ◽  
Primary Star ◽  
True Nature ◽  
Quadruple System ◽  
Data Release ◽  
Host Stars

ABSTRACT A new survey is presented, which explores the second data release of the ESA-Gaia mission, in order to search for stellar companions of exoplanet host stars, located at distances closer than about 500 pc around the Sun. In total, 176 binaries, 27 hierarchical triples, and one hierarchical quadruple system are detected among more than 1300 exoplanet host stars, whose multiplicity is investigated, yielding a multiplicity rate of the exoplanet host stars of at least about 15  per cent. The detected companions and the exoplanet host stars are equidistant and share a common proper motion, as it is expected for gravitationally bound stellar systems, proven with their accurate Gaia astrometry. The companions exhibit masses in the range between about 0.078 and 1.4 M⊙ with a peak in their mass distribution between 0.15 and $0.3\, \mathrm{M}_{\odot }$. The companions are separated from the exoplanet host stars by about 20 up to 9100 au, but are found most frequently within a projected separation of 1000 au. While most of the detected companions are early M dwarfs, eight white dwarf companions of exoplanet host stars are also identified in this survey, whose true nature is revealed with their photometric properties. Hence, these degenerated companions and the exoplanet host stars form evolved stellar systems with exoplanets, which have survived (physically but also dynamically) the post-main-sequence evolution of their former primary star.

Movement in Repose

Qui Parle ◽  
2021 ◽  
Vol 30 (1) ◽  
pp. 19-49
Author(s):  
Aaron Frederick Eldridge
Keyword(s):  
Modern Concept ◽  
Theoretical Argument ◽  
Central Question ◽  
Orthodox Christian ◽  
Crucial Question ◽  
Form Of Life ◽  
Ethnographic Fieldwork ◽  
Philosophical Ethic ◽  
Forms Of Life ◽  
Point Of Departure

Abstract How does tradition, a transmission of body and language, disclose a form of life? This article takes as its point of departure Talal Asad’s methodological pivot away from the modern concept of “belief” to Ludwig Wittgenstein’s concept of “form of life.” It elaborates the philosophical and anthropological implications of a rigorous notion of form of life through Asad’s concept of tradition and Martin Heidegger’s rereading of Aristotle’s physis. Interrupting this theoretical argument, a scene from the author’s ethnographic fieldwork with Orthodox Christian ascetics in Lebanon exemplifies the challenge (and insistence) of form of life. The article then turns to consider a powerful reading of form of life grounded in Baruch Spinoza’s theory of emanation and vitalist univocity. While echoing the concerns of this article, Spinoza’s philosophical ethic defers the central question posed by “form of life” by making the latter a world-producing apparatus. That approach to form of life foregrounds the possibility of being other than what one is, rather than the crucial question of “still experience” and its dynamic repose. The article concludes by reading this still experience alongside C. Nadia Seremetakis’s work in Greece, which details the work of stillness and memory, the deathly pain of history, as sites where the cultivation of noncontemporaneous forms of life are brought into relief.

Demos distracted

2019 ◽  
pp. 142-162
Author(s):  
Sergei Prozorov
Keyword(s):  
Lived Experience ◽  
Human Condition ◽  
Being And Time ◽  
Form Of Life ◽  
Forms Of Life ◽  
The Human Condition

In Chapter 5 Prozorov argues that the ontological contingency that defines democracy is accessible in our lived experience in states of distraction, characterized by the alternation between captivation and boredom. This alternation makes it possible for us to dwell within plural forms of life in a non-definitive manner, retaining our potentiality for being otherwise. He develops this argument by critically re-engaging with Heidegger’s discussion of curiosity and distraction in Being and Time. Prozorov argues that democracy is existentially experienced in the potentiality for perpetual alternation between captivation and boredom in whatever form of life we dwell in, which constitutes our lives as freeform, always manifesting the possibility of being otherwise than they are. In this manner he grounds the possibility of democratic biopolitics in the aspect of the human condition familiar and available to all, thus demonstrating its realizability.

Stellar activity and winds shaping the atmospheres of Earth-like planets

2018 ◽  
Vol 14 (S345) ◽  
pp. 181-184
Author(s):  
Theresa Lueftinger ◽  
Manuel Güdel ◽  
Sudeshna Boro Saikia ◽  
Colin Johnstone ◽  
Beatrice Kulterer ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Extreme Environments ◽  
Doppler Imaging ◽  
Research Network ◽  
Theoretical Understanding ◽  
Stellar Activity ◽  
Active Stars ◽  
Earth Like Planets ◽  
Stellar Magnetic Fields ◽  
Host Stars

AbstractPlanets orbiting young, active stars are embedded in an environment that is far from being as calm as the present solar neighbourhood. They experience the extreme environments of their host stars, which cannot have been without consequences for young stellar systems and the evolution of Earth-like planets to habitable worlds. Stellar magnetism and the related stellar activity are crucial drivers of ionization, photodissociation, and chemistry. Stellar winds can compress planetary magnetospheres and even strip away the outer layers of their atmospheres, thus having an enormous impact on the atmospheres and the magnetospheres of surrounding exoplanets. Modelling of stellar magnetic fields and their winds is extremely challenging, both from the observational and the theoretical points of view, and only ground breaking advances in observational instrumentation and a deeper theoretical understanding of magnetohydrodynamic processes in stars enable us to model stellar magnetic fields and their winds – and the resulting influence on the atmospheres of surrounding exoplanets – in more and more detail. We have initiated a national and international research network (NFN): ‘Pathways to Habitability – From Disks to Active Stars, Planets to Life’, to address questions on the formation and habitability of environments in young, active stellar/planetary systems. We discuss the work we are carrying out within this project and focus on how stellar evolutionary aspects in relation to activity, magnetic fields and winds influence the erosion of planetary atmospheres in the habitable zone. We present recent results of our theoretical and observational studies based on Zeeman Doppler Imaging (ZDI), field extrapolation methods, wind simulations, and the modeling of planetary upper atmospheres.

scholarly journals I. On the action of sunlight on micro-organisms, &c., with a demonstration of the influence of diffused light

1886 ◽  
Vol 40 (242-245) ◽  
pp. 14-22 ◽  
Keyword(s):  
Royal Society ◽  
Bright Sunlight ◽  
Forms Of Life ◽  
Micro Organisms ◽  
Diffused Light ◽  
Solar Rays

Eight years ago, conjointly with my friend Mr. Blunt, I communicated to the Royal Society an account of an experimental inquiry into the action of sunlight on the micro-organisms of putrefaction and decay. We adduced evidence, conclusive in our opinion, that the solar rays were very hostile to these lowly forms of life; so much so that under favourable conditions bright sunlight, sufficiently prolonged, would altogether prevent their appearance in fluids which, under similar conditions of temperature and the like, but screened from light, swarmed in a very few days with countless saprophytes. By means of suitable absorptive media, we learned that the most active rays were those of the more refrangible end of the spectrum.

Extraordinary climates of Earth-like planets: three-dimensional climate simulations at extreme obliquity

2003 ◽  
Vol 2 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Darren M. Williams ◽  
David Pollard
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Three Dimensional ◽  
Terrestrial Planet ◽  
Present Value ◽  
Seasonal Snow ◽  
Climate Simulations ◽  
Nearby Stars ◽  
Earth Like Planets ◽  
The Tropics

A three-dimensional general-circulation climate model is used to simulate climates of Earth-like planets with extreme axial tilts (i.e. ‘obliquities’). While no terrestrial-planet analogue exists in the solar system, planets with steeply inclined spin axes may be common around nearby stars. Here we report the results of 12 numerical experiments with Earth-like planets having different obliquities (from 0° to 85°), continental geographies, and levels of the important greenhouse gas, CO2. Our simulations show intense seasonality in surface temperatures for obliquities [ges ]54°, with temperatures reaching 80–100 °C over the largest middle- and high-latitude continents around the summer solstice. Net annual warming at high latitudes is countered by reduced insolation and colder temperatures in the tropics, which maintains the global annual mean temperature of our planets to within a few degrees of 14 °C. Under reduced insolation, seasonal snow covers some land areas near the equator; however no significant net annual accumulation of snow or ice occurs in any of our runs with obliquity exceeding the present value, in contrast to some previous studies. None of our simulated planets were warm enough to develop a runaway greenhouse or cold enough to freeze over completely; therefore, most real Earth-like planets should be hospitable to life at high obliquity.

scholarly journals Elucidating Forms of Life. The Evolution of a Philosophical Tool

2015 ◽  
pp. 155 ◽  
Author(s):  
Anna Boncompagni
Keyword(s):  
General Attitude ◽  
Philosophical Investigations ◽  
Secondary Literature ◽  
Form Of Life ◽  
Forms Of Life ◽  
Expression Form

Although the expression “form of life” and its plural “forms of life” occur only five times in Philosophical Investigations, and generally few times in his works, it is commonly agreed that this is one of the most relevant issues in Wittgenstein’s later philosophy. Starting from the analysis of the contexts in which Wittgenstein makes use of this concept, the paper focuses on the different interpretations that have been given in secondary literature, and proposes a classification based on two axes of debate: the monistic versus pluralistic interpretation, and the empirical versus transcendental interpretation. After placing some well-known readings in the resulting scheme, an attempt will be made to offer an evolutionary reading of Wittgenstein’s own ideas about forms of life. It will be argued that the empirical and plural view that seems characteristic of his writings in the Thirties, slowly appears to turn towards a monistic view, sometimes with transcendental tones, although within a pragmatic perspective. This turn remains nevertheless rooted in Wittgenstein’s general attitude towards philosophy intended as a conceptual inquiry with clarifying and therapeutic aims.

scholarly journals Forms of Life

2015 ◽  
pp. 1 ◽  
Author(s):  
Peter Hacker
Keyword(s):  
Philosophy Of Language ◽  
Philosophy Of Mathematics ◽  
Language Games ◽  
Truth Conditions ◽  
Philosophical Investigations ◽  
Form Of Life ◽  
Transformation Rules ◽  
Forms Of Life ◽  
A Minor ◽  
Varied History

The phrase ‘Lebensform’ (form of life) had a long and varied history prior to Wittgenstein’s use of it on a mere three occasions in the Philosophical Investigations. It is not a pivotal concept in Wittgenstein’s philosophy. But it is a minor signpost of a major reorientation of philosophy, philosophy of language and logic, and philosophy of mathematics that Wittgenstein instigated. For Wittgenstein sought to replace the conception of a language as a meaning calculus (Frege, Russell, the Tractatus) by an anthropological or ethnological conception. A language is not a class of sentences that can be formed from a set of axioms (definitions), formation and transformation rules and the meanings of which is given by their truth-conditions, but an open-ended series of interlocking language-games constituting a form of life or way of living (a culture). Wittgenstein’s uses of ‘Lebensform’ and its cognates, both in the Investigations and in his Nachlass are severally analysed, and various exegetical misinterpretations are clarified.

scholarly journals Exploring Forms of Life in Player Development Pathways: The Case of British Rugby League

2019 ◽  
Vol 7 (2) ◽  
pp. 242-260 ◽  
Author(s):  
Martyn Rothwell ◽  
Joseph Stone ◽  
Keith Davids
Keyword(s):  
Football Player ◽  
Rugby League ◽  
Environmental Constraints ◽  
Development Research ◽  
Structured Interviews ◽  
Form Of Life ◽  
Complex Interactions ◽  
The United Kingdom ◽  
Forms Of Life ◽  
Rugby League Player

Social, cultural, and historical constraints can influence attitudes towards learning, developing, and performing in sport. A recent conceptualization of these environmental constraints in athlete development pathways is a form of life, which describes the values, beliefs, traditions, customs, and behaviors that contribute to an athlete’s development. Although a form of life can have a powerful influence on athlete development, research exploring this relationship is limited. In this article we explore the form of life in British rugby league football player development contexts to clarify how social, cultural, and historical constraints influence the development of rugby league players in the United Kingdom. Twenty-four coaches were interviewed through individual semi-structured interviews to collect the data. Findings show how forms of life in rugby league player development pathways are established and maintained by the complex interactions between the microsystem, mesosystem, exosystem, and macrosystem that shape and guide the development of players. We recommend that player development pathways in sport underpin practice with a theoretical framework of the learning process to protect athletes from social, cultural, and historical constraints that are not conducive to their development.

3D climate simulations of Earth-like planets with a range of atmospheric composition, radiative transfer, ocean, and resolution configurations, using the new version of ROCKE-3D

2020 ◽  
Author(s):  
Kostas Tsigaridis ◽  
Anthony D. Del Genio ◽  
Igor Aleinov ◽  
Eric T. Wolf ◽  
Maxwell Kelley ◽  
...  
Keyword(s):  
Climate Model ◽  
Sea Surface ◽  
Atmospheric Composition ◽  
Dynamic Simulations ◽  
Climate Simulations ◽  
Wide Range ◽  
Earth Like Planets ◽  
Version 2.0 ◽  
Model Setup

<p>Understanding the climate of terrestrial planetary atmospheres has been increasingly the focus of research worldwide, in light of the increasing amount of rocky planet discoveries orbiting other stars in or near their habitable zone. Here we present simulations with the new version of the 3D climate model ROCKE-3D, whose version 2.0 will soon become publicly available. A wide range of configurations will be supported, compared to a handful ones in its predecessor, version 1.0 (Way et al., 2017). These include two model resolutions (4x5 and 2x2.5), two radiation schemes (GISS and SOCRATES), three atmospheric configurations (Earth-like, Earth-like without O3 and aerosols, and N2-dominated), and three ocean setups (prescribed sea-surface temperatures and ice cover, q-flux, and dynamic). Simulations of all different configuration combinations have been performed and will become available for use by the community. Key results will be presented across those configurations, together of the role of the structural uncertainty in model setup in the resulting climate calculated by the model.</p>

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