III. Ecosmos: A Revolutionary Fertile, Habitable, Solar-Bioplanet, Incubator Lifescape

H. Stellar Planetary Systems: A Stochastic Profusion of Galaxies, Solar Orrerys, and Habitable Zones

Deeg, Hans and Juan Antonio Belmonte, eds. Handbook of Exoplanets. International: SpringerLink, 2018. If ever a vast frontier has opened and become accessible, it is the 21st century’s realization of a fecund universe that innately fills itself with all manner of planetary worlds and solar systems. Beyond 20th century space exploration, a galactic and cosmic neighborhood now beckons for all our futures. After a past decade of prolific global projects, novel instrumentations and computer analyses, this 3,500 volume with 160 authoritative entries is a major documentation to date. Atmospheric Biosignatures, Characterizing Exoplanet Habitability, Dynamic Evolution of Planetary Systems, Exoplanet Catalogs, Host Star Astroseismology, Formation of Giant Planets and Super-Earths, Habitability in Binary Star Systems, Mapping Exoplanets, Planet-Star Interactions, Earth’s Biosignatures Over Time, The Habitable Zone, are just a few areas. As appropriate for our common Earthwise geo-sapience, the entire text is posted online as PDFs on its SpringerLink site. Here are some Abstract edits.

Life on Earth is molecular in nature, with attributes such as information processing and catalysis as a result of those molecules and interactions among them. A general model for life must require (i) a source of energy to build and sustain biochemical complexity and information processing; (ii) elemental raw materials to construct molecules having specific properties and reactivity; (iii) a solvent that supports the range of interactive biomolecules; and (iv) physicochemical conditions in which life’s molecules can be synthesized, stablized, and combine. For life on Earth, these requirements are: (i) light energy in visible-to-near-infrared wavelengths or chemical energy by oxidation–reduction disequilibrium (ii) the biogenic elements carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (iii) liquid water, and (iv) specific ranges in temperature, pH, salinity, pressure, and environmental factors. (Tori Hoehler, et al, Life’s Requirements)

Recent discoveries of exoplanets by both ground-based and space-based surveys indicate that terrestrial-size planets are common around other stars. This raises an intriguing possibility of extraterrestrial life on these planets, which may be detectable with upcoming detailed characterization missions. Consequently, the concept of the habitable zone has been defined to focus the search for life on those planets most likely to be able to sustain liquid water on their surface for extended durations. This chapter addresses the need for such definition, the current state-of-the-art of models that are used to define the habitable zone, and concludes with applications to current and future missions. (Ravi Kopparapu, The Habitable Zone)

A habitable exoplanet is a world that can maintain stable liquid water on its surface. Techniques and approaches to characterizing such worlds are essential, as performing a census of Earthlike planets that may or may not have life will evince how frequently life originates and is sustained on worlds other than our own. Approaches to making the types of measurements that indicate habitability are diverse and have different considerations for the required wavelength range, spectral resolution, maximum noise levels, stellar host temperature, and observing geometry. (Tyler Robinson, Exoplanet Habitability)

The discovery of exoplanets has both focused and expanded the search for extraterrestrial intelligence. The consideration of Earth as an exoplanet, the knowledge of the orbital parameters of individual exoplanets, and the prevalence of exoplanets found throughout the galaxy have altered the search strategies of communication SETI efforts. Future efforts to characterize individual planets with imaging and via transit, will allow for searches for a variety of technosignatures on their surfaces, in their atmospheres, and in orbit around them. (Jason Wright, Exoplanets and SETI)

Deeg, Hans, et al, eds. Extrasolar Planets. Cambridge: Cambridge University Press, 2008. A report from the XVI Canary Islands Winter School of Astrophysics (doesn’t that sound pleasant) on how to detect them, their frequency, characterization, how they might have formed, favorable solar systems, biomarkers, and so on.

Del Genio, Anthony, et al. The Inner Solar System’s Habitability Through Time. arXiv:1807.04776. We cite this entry by Del Genio, NASA Goddard, David Brain, University of Colorado, Lena Noack, Free University of Berlin and Laura Schaefer, Arizona State University for its content, and to note how later 2010s worldwide collaborations are proceeding to reconstruct how our home world came to form and survive, and to scan the celestial raiment as it becomes filled with all manner of near and far neighbor vicarious solar systems and orbital worlds.

Earth, Mars, and Venus, irradiated by an evolving Sun, have had fascinating but diverging histories of habitability. Although only Earth's surface is considered to be habitable today, all three planets might have simultaneously been habitable early in their histories. We consider how physical processes that have operated similarly or differently on these planets determined the creation and evolution of their atmospheres and surfaces over time. These include the geophysical and geochemical processes that determined the style of their interior dynamics and the presence or absence of a magnetic field; the surface-atmosphere exchanges that acted as a source or sink; the Sun-planet interactions that controlled escape of gases to space; and the atmospheric processes that serve to determine climate and habitability. (Abstract)

Deming, David and Sara Seager. Light and Shadow from Distant Worlds. Nature. 462/301, 2009. From NASA and MIT, the latest views on how a plethora of planets are being found due to advancements such as the measurement of eclipse-like luminosities as they transit and orbit their home star.

Within the next decade, we expect to find and study a 'habitable' rocky planet transiting a cool red dwarf star close to our Sun. Eventually, we will be able to image the light from an Earth-like world orbiting a nearby solar-type star. (301)

Deming, Drake, et al. Discovery and Characterization of Transiting Super Earths Using an All-Sky Transit Survey and Follow-up by the James Webb Space Telescope. Publications of the Astronomical Society of the Pacific. 121/952, 2009. As capabilities to detect extrasolar planets become steadily more formidable, a twelve person research team that includes Sara Seager of MIT, and David Charbonneau of Harvard surveys what the frontiers of satellite and terrestrial instrumentation, aided by terabyte computer power, promise for this epochal search. Two main methods are high angular resolution imaging to distinguish orbiting objects from their star, and a blending of the light from a planet and star in transiting systems. To restate, the immense payoff for we people would be an appreciation of earth’s precious place and purpose in this fertile cosmic nursery.

Dohm, James and Shigenori Maruyama. Habitable Trinity. Geoscience Frontiers. 6/1, 2015. In this online journal from the China University of Geosciences, Tokyo Institute of Technology, Earth-Life Science Institute researchers advise that a biologically favorable world needs a conducive meld of land forms, water in oceans, and a relatively benign atmosphere. As the second quote says, another trinity has coalesced to define living systems by way of a membrane enclosure, viable metabolism, and informational self-replication. From this late vantage, life’s whole temporal and global course can be reconstructed in images and diagrams, as throughout the paper. See also Unified Theory of Biological Evolution by Maruyama and Toshikazu Ebisuzaki in the same issue.

Habitable Trinity is a newly proposed concept of a habitable environment. This concept indicates that the coexistence of an atmosphere (consisting largely of C and N), an ocean (H and O), and a landmass (supplier of nutrients) accompanying continuous material circulation between these three components driven by the Sun is one of the minimum requirements for life to emerge and evolve. The life body consists of C, O, H, N and other various nutrients, and therefore, the presence of water, only, is not a sufficient condition. Habitable Trinity environment must be maintained to supply necessary components for life body. Our Habitable Trinity concept can also be applied to other planets and moons such as Mars, Europa, Titan, and even exoplanets as a useful index in the quest for life-containing planetary bodies. (Abstract)

What is Life?: For biologists, the three-fold definition is common: (1) a membrane to separate the life body from the outer world, through which necessary elements for life such as water enter and exit the cell, (2) a metabolism which is a set of chemical reactions occurring in a living organism, such as receiving energy through spending nutrients and sugar, and (3) self-replication which allows life to continue through time. (95)

Dominik, Martin and John Zarnecki. The Detection of Extra-Terrestial Life and the Consequences for Science and Society. Philosophical Transactions of the Royal Society A. 369/499, 2011. As the discovery of an innately prolific cosmos which seems by its nature to be filled with orbital earth-like planets begins to register, this issue here introduced considers how to imagine, search for, assimilate, accommodate, and respond to an evident prevalence of myriad intelligent bioworlds. A stellar cast includes Christian de Duve (search), Kathryn Denning, Simon Conway Morris, Paul Davies, veteran Frank Drake, Michel Mayor, and many others.

Dorn, Caroline, et al. Assessing the Interior Structure of Terrestrial Exoplanets with Implications for Habitability. arXiv:1710.05605. Astrophysicists Dorn, University of Zurich, Dan Bower, University of Bern, and Antoine Rozel, ETH Zurich write a chapter for the 2018 Handbook of Exoplanets ((Deeg, SpringerLink) as these solar, galactic, and cosmic studies proceed with new sophistications of deep planetary geology, along with liquid and gaseous phases. See, for example, Jupiter’s Stormy Winds Churn Deep into the Planet in Nature (550/437).

Astrophysical observations reveal a large diversity of radii and masses of exoplanets. It is important to characterize the interiors of exoplanets to understand planetary diversity and further determine how unique, or not, Earth is. Assessing interior structure is challenging because there are few data and large uncertainties. Thus, for a given exoplanet a range of interior structure models can satisfy available data. Typically, interior models aim to constrain the radial structure and composition of the core and mantle, and additionally ice, ocean, and gas layer if appropriate. Nevertheless, elucidating interior dynamics remains a key goal in exoplanetology due to its role in determining surface conditions and hence habitability. Thus far, Earth-like habitability can be excluded for super-Earths that are in close proximity to their stars and therefore have high surface temperatures that promote local magma oceans. (Abstract excerpts)

The primary constituents that may contribute to a terrestrial planet are: (1) iron-rich core, (2) rocky mantle, (3) hydrogen-dominated gas layer accreted from the circumstellar disk, (4) heavy mean molecular weight gas layer that originates from interior outgassing (5) massive water layers. In this chapter we focus attention on super-Earth that have small radius fractions (less than a few percent) of volatiles (gas and water); for these planets the negligible contribution of volatiles does not significantly affect the planetary mass and radius. However, we do give precursory consideration to other possible planetary interiors since we cannot necessarily confirm a priori which interior model is most appropriate for a given exoplanet. (2)

Doyle, Laurance, et al. Kepler-16: A Transiting Circumbinary Planet. Science. 333/1602, 2011. Et al runs to some 48 names including major players such as Geoffrey Marcy and Alan Boss to Debra Fischer and Dimitar Sasselov who are ecstatic about finding this exo-world orbiting around a two stars – a double sun. What wonders await as we altogether explore a fertile cosmos that seems to seed itself in every manner and locale with ovular earths.

Drazkowaka, Joanna. Planet Formation Theory in the Era of ALMA and Kepler: From Pebbles to Exoplanets. arXiv:2203.09759. This entry with some 450 references can stand as an extensive report to date about our Earthwise collegial retrospect of how this home and other orbital objects came to form. It will be presented at the Protostars and Planets VII meeting in Kyoto next April 2023 (twice proponed) and be a chapter in a University of Arizona Press volume with that title.

Our understanding of planet formation has been rapidly evolving in recent years. The classical model from the 1990s was based on our own Solar System, is being constantly revised. Here we summarize many new findings derived from the exoplanet population and circumstellar disks observations such as the growth of planetary cores by accretion of planetesimals, pebbles, and gas, along with massive planetary cores and more occasions. In addition, there is growing evidence that the first planetary cores start forming early, during the circumstellar disk buildup process. (Abstract excerpt)

Drazkowska, Joanna, et al. Planet Formation in the Era of ALMA and Kepler: From Peebles to Exoplanets. arXiv:2203.09759. In a paper for Protostars and Planets VII, astronomers in Germany, Sweden, Chile, Taiwan, Israel, China, the USA, and France (Alessandro Morbidelli) provide the latest comprehensive survey from our home base of how an ever increasing array of diverse exoworlds might have been formed.

. In this chapter, we summarize the new information derived from the exoplanets population and the circumstellar disks observations. We present the new developments in planet formation theory, from dust evolution to the growth of planetary cores by accretion of planetesimals, pebbles, and gas. We review the state-of-the-art models for the formation of diverse planetary systems, including the population synthesis approach which is necessary to compare theoretical model outcomes to the exoplanet population. In addition, there is growing evidence that the first planetary cores start forming early, during the circumstellar disk buildup process. (Excerpt)

Dvorak, Rudolf, ed. Extrasolar Planets: Formation, Detection, and Dynamics. Weinheim: WILEY-VCH Verlag, 2008. Akin to current Deeg and Mason works posted here, technical papers on all such aspects as Earthkind begins to scan the celestial horizons for other worlds.

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