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

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

Villard, Ray. Is Earth One of a Kind? Astronomy. April, 2009. In just nine years since the gloomy premise of Ward and Brownlee’s Rare Earth: Why Complex Life is Uncommon in the Universe that a bioplanet with reflective sentience must be a vanishing improbability is in the process of being repealed. As this section documents, a galactic proliferation of solar systems with planets of every size and kind is now discovered. Among the recent revisions: Earth’s elements are not rare, a large moon is not critical, many stars are sun-like, life’s Cambrian burst is not a unique event, and so on.

Given the vast number of stars in our Milky Way, astronomers predict our galaxy may hold as many as one trillion planets. Even if one out of one million meets the above-described conditions, our galaxy would still contain at least one million Earth clones. (39)

Walker, Sara, et al. Exoplanet Biosignatures: Future Directions. arXiv:1705.08071. A 123 page summary paper for a 2016 workshop by this title (search) by a 14 member team including Leroy Cronin, William Bains, Betul Kacar, and Nancy Kiang. In regard, an intelligent Earthkinder begins to explore and quantify a fertile, galactic and cosmic milieu which innately fills itself with abundant evolutionary bioworlds. Many aspects and methods such as Bayesian statistics, geochemical environs, definitions of a universal biology, evolutionary essences, solar systems candidates, and so on, are considered.

Exoplanet science promises a continued rapid accumulation of new observations in the near future, energizing a drive to understand and interpret the forthcoming wealth of data to identify signs of life beyond our Solar System. The large statistics of exoplanet samples, combined with the ambiguity of our understanding of universal properties of life and its signatures, necessitate a quantitative framework for biosignature assessment Here, we introduce a Bayesian framework for guiding future directions in life detection, which permits the possibility of generalizing our search strategy beyond biosignatures of known life. The Bayesian methodology provides a language to define quantitatively the conditional probabilities and confidence levels of future life detection and, importantly, may constrain the prior probability of life with or without positive detection. We describe empirical and theoretical work necessary to place constraints on the relevant likelihoods, including those emerging from stellar and planetary context, the contingencies of evolutionary history and the universalities of physics and chemistry. We discuss how the Bayesian framework can guide our search strategies, including determining observational wavelengths or deciding between targeted searches or larger, lower resolution surveys. Our goal is to provide a quantitative framework not entrained to specific definitions of life or its signatures, which integrates the diverse disciplinary perspectives necessary to confidently detect alien life. (Abstract)

Wang, Haiyang, et al. The Elemental Abundances (with Uncertainities) of the Most Earth-like Planet. arXiv:1708.08718. As our collaborative humankinder proceeds to quantify the cosmos, Australian National University astrophysicists Wang, Charles Lineweaver, and Trevor Ireland contribute a geochemical assay of Earth’s material composition. Whom then are we curative creatures to appear as the universe’s way of learning this, and for what purpose?

To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky exoplanets based on their stellar hosts' elemental abundances, we need a better understanding of the devolatilization that produced the Earth. To quantify the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. Here we present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, which can be used in such studies. Our concordance estimates for the abundances of Mg, Sn, Br, B, Cd and Be are significantly lower than previous estimates of the bulk Earth. Our concordance estimates for the abundances of Na, K, Cl, Zn, Sr, F, Ga, Rb, Nb, Gd, Ta, He, Ar, and Kr are significantly higher. The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under various geochemical and geophysical assumptions. (Abstract excerpts)

Wang, Yun, et al. ATLAS Probe: Breakthrough Science of Galaxy Evolution, Cosmology, Milky Way, and the Solar System. arXiv:1802.01539. A 39 member international team posts an Astrophysics Telescope for Large Area Spectroscopy project concept for a NASA mission, circa 2030, to follow up the mid 2020s WFIRST Wide-Field Infrared Survey Telescope. As the quotes cite, we ought to appreciate how actually awesome is this grand humankinder endeavor. A sapient, collaborative species on a minute bioworld yet can embark forthwith to quantify any spatial and temporal breadth and depth of galactic, stellar, and material realms. But we are still not moved to ask what kind of a greater cosmic reality evolves toward and seems to require its own internal self-description. Whom are we brilliant beings summoned to do this, as if a genesis universe were trying to pass its future procreation to our intentional agency?

ATLAS Probe science spans four broad categories that address the five fundamental questions: (1) revolutionize galaxy evolution studies by tracing the relation between galaxies and dark matter from galaxy groups to cosmic voids and filaments, from the epoch of reionization through the peak era of galaxy assembly; (2) open a new window into the dark Universe by weighing the dark matter filaments in the cosmic web using 3D weak lensing, and obtaining definitive measurements of dark energy and tests of General Relativity using galaxy clustering; (3) probe the Milky Way’s dust-enshrouded regions, reaching the far side of our Galaxy; and (4) characterize Kuiper Belt Objects and other planetesimals in the outer Solar System. (3)

ATLAS Probe will be capable of transforming the state of knowledge of how the Universe works by the time it launches in ∼ 2030. (4) ATLAS is designed to watch galaxies emerge and grow within the cosmic web during the first half of cosmic history. ATLAS Probe is designed to reveal the detailed structure of the cosmic web. (7) TLAS Probe is a compelling mission concept for a NASA probe-class mission. It is a follow-up space mission to WFIRST; it multiplexes the scientific return of WFIRST by obtaining spectra of ∼90% of all galaxies imaged by the WFIRST High Latitude Survey at z> 0.5. Enabled by the mature DMD technology that allows a spectroscopic multiplex factor of 5,000 to 10,000, ATLAS Probe will lead to ground-breaking science over the entire range of astrophysics: from galaxy evolution to the dark Universe, from objects in the outer Solar System to the dusty regions of the Milky Way. (36)

Weinberger, Alycia. Building Planets in Disks of Chaos. Sky & Telescope. November, 2008. A Carnegie Institution of Washington astronomer explains how the ubiquitous presence of orbiting dust disks can be noticed as a signature of protoplanetary nurseries. (See also in the September S. & T. “Planetary Peculiarities” by Ken Croswell, and “Are Super-Sized Earths the New Frontier” by Ray Jayawardhana in the November 2008 issue of Astronomy.)

Giant collisions, rogue asteroid swarms – planet building is messy and unpredictable, and it sometimes leaves lots of debris. But one way or another, it seems to happen around most stars. (32) But I prefer to think of disks as signals rather than noise. They signal that planetary formation is common. Their constituents may tell us about how planets become hospitable for life. And they are beacons of the long-past era when our Sun came to host a place able to produce astronomers who look out and wonder. (37)

Weiss, Lauren, et al. Architectures of Compact Multi-planet Systems. arXiv:2203.10076. Seven astro-authorities contribute to this presentation to be made at the 2023 Protostars and Planets VII conference in Kyoto, Japan (see below). Some other coauthors are Fred C. Adams, Erik Petigura, and Konstantin Batygin. After a two year –demic hiatus, hopefully our EarthWise scientific endeavors to explore, quantify, describe and learn from this stellar spacescape.can proceed apace. For an earlier view see Peas in a Pod: Planets in a Kepler Multi-planet System are Similar in Size and Regularly Spaced by Lauren Weis, et al at 1706.06204.

One of the most important developments in exoplanet science in the past decade is the discovery of multi-planet systems with sub-Neptune-sized planets. This chapter explores their architectures, which often display a high degree of uniformity of similar sizes, regular orbital spacing, low eccentricities, and small inclinations. We begin with a critical review and find that these peas-in-a-pod planetary systems may be a common outcome of planet formation processes. Stars form along with circumstellar disks with a tendency to produce these planetary systems. In summary, interesting observational and theoretical challenges remain in order to understand how these surprisingly organized planetary systems arise from the relative disorder of their formation processes. (Abstract excerpt)

Taking a step back, we can think of the striking uniformity found in compact multi-planet systems as an example of self organization. In general, any self-organizing system has a primary driving force that acts to create structure and some “counter-force” that acts as a stabilizing influence. In the present context, the peas-in-a-pod architecture typical of compact multis contains close planet masses and regular orbital spacing. With the peas-in-a-pod pattern becoming well-established, the future work needs to identify the driving forces and counter-forces that lead to such interesting planetary systems. (18)

Protostars & Planets VII, twice postponed, this meeting will take place in Kyoto on April 10th – 15th of 2023. This conference series has provided an important opportunity for scientists working on the formation of stars and planets. We would like to have a series of review talks summarizing the development in our field in recent years. The Protostars & Planets Series by the University of Arizona Press will then publish a chapter volume of papers.

Werner, Michael and Michael Jura. Improbable Planets. Scientific American. June, 2009. Werner, chief NASA scientist for the Spitzer Space Telescope, and Jura, a UCLA astronomer, extol the rush of instrumental findings that reveal a new cosmos which proliferates worlds, planetary objects, stars, and solar systems of every possible variety. And on one earth, evidently as if a fertile seed or egg, life and mind evolves and quickens as if a planetary person being born to and exploring its nursery, as a genesis universe begins to witness and imagine itself.

Astronomers hardly expected the ubiquity of planetary systems, their hardiness and the apparent universality of the processes by which they form. (39)

Wiedner, Martina, et al. Origins Space Telescope: From First Light to Life: ESA Voyage 2050 White Paper. arXiv:2012.02731. A 27 member team from the European Space Agency posts their grant proposal which was one of four selected for this international project. It is based on three questions: How does the Universe work?, How did we get here?, Are we alone? And to take a philoSophia view, a nascent worldwise knowledgeable sapience becomes able to recreate and envision the whole vast scenario it arose from. Who are me/We beings that can altogether learn the the galactic baryon cycle? Might our Earthmost home be a fittest, optimum candidate? Here is another instance of a major personsphere transition proceeding to come to her/his own discoveries.

The Origins Space Telescope is one of four science and technology definition studies selected by NASA for the 2020 Astronomy and Astrophysics Decadal survey in the USA. Origins will trace our history from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. It is designed to answer three major science questions: How do galaxies form stars, make metals, and grow their central supermassive black holes from reionization? How do the conditions for habitability develop during the process of planet formation? Do planets orbiting M-dwarf stars support life? (Abstract excerpt)

Winn, Joshua and Daniel Fabrycky. The Occurrence and Architecture of Exoplanetary Systems. arXiv:1410.4199. A chapter to appear by September in the Annual Review of Astronomy and Astrophysics, Volume 53, 2015, by an MIT physicist and a University of Chicago astronomer. This astronomical discovery of a cosmic neighborhood innately filled worlds of every kind was unimaginable before 1995, and a sporadic occurrence before the Kepler 2009 launch. Today a plethora of articles as this describe a radically new planetary nursery being revealed to our Earthly surveillance.

The basic geometry of the Solar System -- the shapes, spacings, and orientations of the planetary orbits -- has long been a subject of fascination as well as inspiration for planet formation theories. For exoplanetary systems, those same properties have only recently come into focus. Here we review our current knowledge of the occurrence of planets around other stars, their orbital distances and eccentricities, the orbital spacings and mutual inclinations in multiplanet systems, the orientation of the host star's rotation axis, and the properties of planets in binary-star systems. (Abstract)

Winter, Andrew, et al. Stellar Clustering Shapes the Architecture of Planetary Systems. Nature. 586/528, 2020. University of Heidelberg and University of Leichester astrophysicists review observational and experimental studies about the ways that solar systems may form and arrange themselves. A propensity for sunny stars to bunch together in groups then becomes a factor with regard to the relative habitability of orbital worlds.

Conclusions:Our results show that stellar clustering is a key factor setting the architectures of planetary systems. This environment represents a fundamental axis along which exoplanetary and atmospheric properties may vary, and which has implications for planetary habitability and the likelihood of life in the Universe. Star formation was likely more clustered in the past, so that an influence on older planetary systems may have been even greater. (532)

wolf, Eric, et al. Constraints on Climate and Habitability for Earth-like Exoplanets Determined from a General Circulation Model. arXiv:1702.03315. Astrophysicists from the University of Colorado (Wolf and Owen Toon), UC Irvine (Aomawa Shields), NASA Goddard (Ravi Kopparapu), and Jacob Haqq-Misra (NASA Astrobiology) study which fluidly interactive surface and atmospheric parameters might favor or constrain evolutionary life forms. Thermodynamic forces are seen to cause sharp transitions between certain snowball, waterbelt, temperate, and moist greenhouse states. Radiation, convection, clouds, ocean heat transport, sea ice, and more are implicated in a relative suitability and sustainability. See also, for example Atmospheric Tides in Earth-like Planets by Pierre Auclair-Desrotour, et al in Astronomy & Astrophysics (Online December, 2016).

Yang, Sheng, et al. The stability of unevenly spaced planetary systems. arXiv:2308.16798. We first post this paper about solar system by seven astrophysicists across China so that it is online. A longer review will follow.

Studying the orbital stability of multi-planet systems is essential to understand planet formation, estimate the stable time of an observed planetary system, and advance population synthesis models. Although previous studies have primarily focused on ideal systems characterized by uniform orbital separations, in reality a diverse range of orbital separations exists among planets within the same system. This study focuses on investigating the dynamical stability of systems with non-uniform separation. We considered a system with 10 planets with masses of 10−7 solar masses around a central star with a mass of 1 solar mass. We conclude that when estimating the orbital crossing time and colliding pairs in a realistic situation, updating the formula derived for evenly spaced systems would be necessary. (Excerpt)

The N-body simulation results are as follows:
• Orbit crossing times become shorter in the case of pairs with shorter initial orbital separations.
• There is a correlation between the closest separation pair and the first close encounter or collision.
• The orbital crossing time for systems with uneven orbital separation could be expressed based on the orbital periods of the closest separation pair. (5)

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