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

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

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.

Elkins-Tanton, Linda and Benjamin Weiss, eds. Planetesimals: Early Differentiation and Consequences for Planets. Cambridge: Cambridge University Press, 2017. The editors are the Director of the School of Earth and Space Exploration at Arizona State University, and the Chair of the Program in Planetary Sciences at MIT. As collaborative humankinder proceeds to reconstruct how exoworlds and this home Earth came to form from such seed-like origins, this volume covers their Dynamical Evolution, Chemical and Mineralogical Diversity, Asteroids as Records of Formation and Differentiation, and Early Differentiation and Consequences for Planet Formation. Ought we to then wonder, what global sapient faculty rises out of such a vicarious ancestry to achieve cosmic self-retrospective?

Processes governing the evolution of planetesimals are critical to understanding how rocky planets are formed, how water is delivered to them, the origin of planetary atmospheres, how cores and magnetic dynamos develop, and ultimately, which planets have the potential to be habitable. Theoretical advances and new data from asteroid and meteorite observations, coupled with spacecraft missions such as Rosetta and Dawn, have led to major advances in this field over the last decade. This transdisciplinary volume presents an authoritative overview of the latest in our understanding of the processes of planet formation. Combining meteorite, asteroid and icy body observations with theory and modelling of accretion and orbital dynamics, this text also provides insights into the exoplanetary system and the search for habitable worlds. This is an essential reference for those interested in planetary formation, solar system dynamics, exoplanets and planetary habitability. (Summary)

Elser, Sebastian, et al. How Common are Earth-Moon Planetary Systems? Icarus. 214/2, 2011. In Rare Earth (2000) Peter Ward and Donald Brownlee say that a planet with a large moon is helpful for life to evolve, but worry that the system would be statistically unusual. Drawing on a decade of celestial advances, University of Zurich and University of Colorado astrophysicists now contend that such couplings are much more common. Indeed, along with many other findings, the Ward and Brownlee case has been largely refuted. On the contrary, our galaxy and the whole cosmos seems made to innately seed itself with conducive bioearths.

The Earth’s comparatively massive moon, formed via a giant impact on the proto-Earth, has played an important role in the development of life on our planet, both in the history and strength of the ocean tides and in stabilizing the chaotic spin of our planet. Here we show that massive moons orbiting terrestrial planets are not rare. A large set of simulations by Morishima et al. (Morishima, R., Stadel, J., Moore, B. [2010]. Icarus. 207, 517–535), where Earth-like planets in the habitable zone form, provides the raw simulation data for our study. We use limits on the collision parameters that may guarantee the formation of a circumplanetary disk after a protoplanet collision that could form a satellite and study the collision history and the long term evolution of the satellites qualitatively. We find that giant impacts with the required energy and orbital parameters for producing a binary planetary system do occur with more than 1 in 12 terrestrial planets hosting a massive moon, with a low-end estimate of 1 in 45 and a high-end estimate of 1 in 4. (Abstract, 357)

Emsenhuber, Alexandr, Alexandre, et al. Planetary Population Synthesis and the Emergence of Four Classes of Planetary System Architectures. arXiv:2303.00012. We note this work by Ludwig-Maximilians-Universit, University of Bern, and MPI Astronomie exo-researchers as another example of new perceptions of how solar systems seem to have an array of overall properties.

Here, we review the population synthesis method to explore which conditions lead to different planetary system architectures. As a result, we identify four main groups: a near-in situ compositionally ordered terrestrial and ice planets, migrated sub-Neptunes, mixed low-mass and dynamically active giants without inner low-mass planets. These four classes exhibit typical formation pathways and are certain mass scales. The breakdown into classes allows to better understand which physical processes are dominant. Comparison with observations reveals certain differences to the actual population, pointing at limitation of theoretical understanding. (Excerpt)

Faridani, Thea, et al. More Likely Than You Think: Inclination-Driving Secular Resonances are Common in Known Exoplanet Systems.. arXiv:2406.09359.. We cite this work by UCLA, Georgia Tech and Yale University astroscientists as another current perception of solar systems as a whole interactive entity wherein planetary locations and transits influence each other. See also The PLATO Mission at arXiv:2406.05447 for another version.

Multi-planet systems face significant challenges to detection. One mechanism to excite mutual inclination between planets is secular resonance, where the nodal precession frequencies align such as to increase the efficiency of angular momentum transport between them. In this work, we explore known three-planet systems, determine whether they are in (or were in) secular resonance due to evolving stellar oblateness, and demonstrate the implications of resonance on their detectability and stability. We show that about 20% of three planet transiting systems seem to undergo these resonances early in their lives. (Excerpt)

Fields, Benjamin, et al. Information Gain as a Tool for Assessing Biosignature Missions. International Journal of Astrobiology. July, 2023. Blue Marble Space Institute of Science researchers BF, Sohom Gupta and McCullen Sandora propose a better, systematic approach as we Earthlings embark on a near and farther celestial census to bravely seek out, evaluate potential neighbors. Hello. is anyone there?

We propose the mathematical notion of information gain as a way to best assess the value of biosignature searches. This approach applies to many case examples: the minimal number of samples to see a trend in signal occurrence rate as a function of an environmental variable, and how much cost to allocate to aspect; false positives and false negatives, tradeoffs between resolution and coverage; how to deduce a habitability boundary; and much more. In each case, we state quantitative, optimum recommendations for mission design, selection, and/or target choice. (Excerpt)

Blue Marble Space Institute is an international community based in Seattle engaged in building a sustainable future guided by scientific knowledge. Our mission is to explore life as a universal phenomenon. We publish in academic journals, and through seminar series as well as the SAGANet social network. We pursue aspects such as: How did life on Earth originate, How does human civilization and the Earth system co-evolve and How unique is Earth among other planets in the galaxy.

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