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

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

Boyle, Rebecca. Astronomers Reimagine the Making of the Planets. Quanta. June 6, 2022. A science writer continues to survey our worldwise retrospective studies of how this Earth, our solar system, and orbital orrerys tend to array into myriad varieties. Her prior report was As Planet Discoveries Pile Up, a Gap Appears in the Pattern (May 16, 2019) which noted an absence in the galaxy of 1.5 to 2 times Earth size worlds. Three years and 5,000 total findings later, still “none that remotely resemble ours” was found She comments that Alessandro Morbidelli, a leading researcher, finds the situation quite curious. A prime reference is then Planet Formation Theory in the Era of ALMA and Kepler: From Pebbles to Exoplanets by Joanna Drazkowaka and nine coauthors including AM at arXiv:2203.09759 (see herein).

Burkhardt, Christoph. Planetary Genealogy. arXiv:2203.02203. A University of Munster researcher deftly employs this familial metaphor so to impart a deep sense of an astro-ancestry.

The detection of exoplanets and accretion disks around newborn stars has spawned novel models of how our Solar System formed and evolved. In regard, stable isotope anomalies in meteorites are now used as key tracers of material flow in the early Solar System which allows cosmochemists to establish a "planetary isotopic genealogy". This concept has advanced our understanding of Solar System evolution from the collapse of the Sun's parental molecular cloud. (Abstract excerpt)

Isotope anomalies are adding new vistas to the Solar System’s dynamical evolution from the molecular cloud to the formation of the terrestrial planets. As if genetic tracers, they reveal a bimodality among planetary bodies that dates back to the early infall stage. Many questions remain, but, planetary isotope genetics has the potential to bring meteoritics, astronomical observations, and modeling together towards a unified model for early Solar System evolution. (8)

Burn, Remo,et al. A radius valley between migrated steam worlds and evaporated rocky cores. Nature Astronomy. 8/4, 2024. MPI Astronomy, University of Bern, IBM Research, and Geneva Observatory and Ludwig-Maximilians-University astrophysicists including Julia Venturini are able to detect the presence of an integral solar system topology which serves to array and constrain planetary movements. See also Peas-in-a-Pod Across the Radius Valley: Rocky Systems are Less Uniform in Mass but More Uniform in Size and Spacing by Armaan Goyal and Songhu Wang at arXiv:2405.14091 and Wide Binary Orbits are Preferentially Aligned with the Orbits of Small Planets, but Probably Not Hot Jupiters by Sam Christian, et al at 2405.10379.

The radius valley (or gap) which separates smaller super-Earths from larger sub-Neptunes, is a key feature that theoretical models must explain. Here we use an advanced coupled formation and evolution model that describes the planets’ growth and evolution starting from solid, moon-sized bodies in the protoplanetary disk to mature Gyr-old planetary systems. The model results demonstrate that the observed radius valley can be interpreted as the separation of less massive, rocky super-Earths formed in situ from more massive, ex situ, water-rich sub-Neptunes. Therefore, we provide a hybrid theoretical explanation of the radius gap and cliff caused by both planet formation (orbital migration) as well as evolution (atmospheric escape). (Excerpt)

Burrows, Adam and Geoffrey Marcy. Exoplanets. Proceedings of the National Academy of Sciences. 111/12599, 2014. An introduction to authoritative papers as a current update upon this fledgling field dubbed Comparative Exoplanetology. The endeavor has seen two phases – Marcy and colleagues detection circa 1995 of another orbital world and the post 2009 Kepler satellite findings of a galaxy and cosmos filled with as many planets as stars. Articles such as The Future of Spectroscopic Life Detection on Exoplanets by Sara Seager, Exploring Exoplanet Populations with NASA’s Kepler Mission by Natalie Batalha, Structure of Exoplanets by David Spiegel, et al, Requirements and Limits for Life in the Context of Exoplanets by Chris McKay, and Remote Life-Detection Criteria, Habitable Zone Boundaries, and the Frequency of Earth-like Planets around M and Late K Stars by James Kasting, et al open vistas upon a revolutionary habitable universe. How incredible that our precious Earth by way of a late worldwide collaboration, sophisticated instrumentation, computer analysis, is now able to realize, explore, quantify, atmospheres, signs of life, stochastic frequencies, and so on. We have just begun to imagine an actual fecund ecosmos which by its own propensities seems to sow and seed itself with ovular worlds in solar incubators.

Byrne, Xander, et al. Atmospheres as a Window to Rocky Exoplanet Surfaces. arXiv:2312.11133.. As our worldwise neighborhood census expands apace, four Cambridge University astronomers including Oliver Shorttle propose that further insights could be achieved by probing deeper into their geospheres. See also companion efforts such as Phanerozoic biological reworking of the continental carbonate rock reservoir at 2312.09011, Past and Present Dynamics of the Iron Biogeochemical Cycle at 2312.09044, and Coupled atmospheric chemistry, radiation, and dynamics of an exoplanet generate self-sustained oscillations by Yangcheng Luo, et al in PNAS (120/51, 2023) as this Earthmost work of ecosmic quantification goes forth.

As findings about exoplanet atmospheres quantify their chemistry and composition, we ask how much deeper can these studies go. For small planets with modest atmospheres, the first layer will be their rocky surface. Using an equilibrium chemistry code, we find a boundary in surface pressure-temperature space which simultaneously separates distinct mineralogical regimes and atmospheric regimes, enabling inference of surface mineralogy from spectroscopic observations of the atmosphere. Our results pave the way to the prospect of characterizing exoplanetary surfaces as new data for short period rocky planet atmospheres emerge. (Excerpt)

Our results demonstrate strongly non-linear crustal evolution after the rise of the complex Phanerozoic biosphere. This outcome suggests that complex life may generate unique biogeochemical trajectories on otherwise geologically similar worlds, posing a new challenge in the hunt for life beyond Earth. (2312.09044)

Cabrol, Nathalie. The Coevolution of Life and Environment on Mars. Astrobiolog. 18/1, 2018. The French-American, SETI Institute Carl Sagan Center, planetary scientist scopes out a research program which sets up a relative contrast between Earth and Mars with regard to early life stages, gain and loss of habitability, and geo-atmospheric conditions. Although one woman is doing this, the greater project is due altogether to a thinking planet as it just now proceeds to consider a neighbor world by way of similar temporal and spatial environments.

Cabrol, Nathalie. Using Machine Learning to Optimize the Search for Biosignatures. Nature Astronomy. 7/3, 2023. We cite this article by the senior French-American astrobiologist and director of the Carl Sagan Center for the Study of Life in the Universe at the SETI Institute as such a far and wide celestial neighborhood census becomes facilitated by AI methods (see our EI section).

A probabilistic machine learning-based framework for recognizing and predicting microbial landscape patterns at nested spatial scales was developed. The approach substantially increased the probability of detecting biosignatures when tested at a Martian analogue in the high Andes. This search tool has applications for detecting biosignatures on terrestrial or icy planets.

Carroll, Michael. The Hunt for Earth’s Bigger Cousins. Astronomy. April, 2017. As worldwide humankind continues to explore, discover and quantify a widest array of planetary objects, many articles as this keep up with their findings. Here a science writer and author of Earths of Distant Suns (2016) notes that a most prevalent size seems to be 2 to 10 times our home planet, which are known as Super Earths or Sub Neptunes. We also enter because in several places it is observed that this orderly solar system is an anomaly amongst the usual chaos, continents in motion via plate tectonics are rare, wholly gaseous atmospheres are common, and so on. So the case of an extraordinary great Earth continues to build.

Cassan, Arnaud, et al. One or More Bound Planets per Milky Way Star from Microlensing Observations. Nature. 481/167, 2012. A team of some 41 scientists within the Probing Lensing Anomalies Network (PLANET) collaboration, based at Institut d’Astrophysique de Paris, Université Pierre and Marie Curie, further support the 21st century revolution to realize an innately conducive cosmos that seemingly seeds itself with as many worlds as there are stars in the sky.

We conclude that stars are orbited by planets as a rule, rather than the exception. (167) Planets around stars in our Galaxy thus seem to be the rule rather than the exception. (169)

Chang, Kenneth. 7 Earth-Size Planets Orbit Dwarf Star, NASA and European Astronomers Say. New York Times. February 23, 2017. As a graphic display to lead the front page, this is a report about the widely-noted discovery of the most solar system-like, multi-world array found to date. We also note that while a cooperative humanity can reveal such frontiers, as readers know, the rest of the daily news was about a precious planet consumed with barbaric, terminal violence.

Not just one, but seven Earth-size planets that could potentially harbor life have been identified orbiting a tiny star not too far away, offering the first realistic opportunity to search for signs of alien life outside the solar system. The planets orbit a dwarf star named Trappist-1, about 40 light-years, or 235 trillion miles, from Earth. All seven are very close to the dwarf star, circling more quickly than the planets in our solar system. The innermost completes an orbit in just 1.5 days. The farthest one completes an orbit in about 20 days. That makes the planetary system more like the moons of Jupiter than a larger planetary system like our solar system.

Chen, Jingjing and David Kipping. Probabilistic Inference of the Masses and Radii of Other Worlds. arXiv:1603.08614. Columbia University astronomers look back upon the past two decades, especially by the Kepler satellite, of novel planetary discoveries to propose four object classes – Terran (rocky earths), Neptunian worlds, larger Jovian orbs (both gaseous) and stars. By these views, the so-called Super Earths actually appear to be mini-Neptunes or gas dwarfs. It is thus concluded: This independent analysis adds further weight to the emerging consensus that rocky Super-Earths represent a narrower region of parameter space than originally thought. Effectively, then, the Earth is the Super-Earth we have been looking for.

Chiang, Eugene and Gregory Laughlin. The Minimum-Mass Extrasolar Nebula: In Situ Formation of Close-in Super-Earths. Monthly Notices of the Royal Astronomical Society. 431/3444, 2013. In a typical paper now infusing such august journals, University of California, Berkeley, and Santa Cruz, astrophysicists continue to show how profligate cosmic nature is when it comes to seeding herself with all manner of solar-planetary systems and ovular bioworlds.

Close-in super-Earths, with radii R ≈ 2–5R⊕ and orbital periods P < 100 d, orbit more than half, and perhaps nearly all, Sun-like stars in the Universe. We use this omnipresent population to construct the minimum-mass extrasolar nebula (MMEN), the circumstellar disc of solar-composition solids and gas from which such planets formed, if they formed near their current locations and did not migrate. In a series of back-of-the-envelope calculations, we demonstrate how in situ formation in the MMEN is fast, efficient, and can reproduce many of the observed properties of close-in super-Earths, including their gas-to-rock fractions. Testable predictions are discussed. (Abstract)

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