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

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

Millholland, Sarah and Joshua Winn. Split Peas in a Pod: Intra-System Uniformity of Super-Earths and Sub-Neptunes. arXiv:2110.01466. Princeton University astrophysicists contribute to growing perceptions that entire solar orrery planetary systems have an overall mathematic formative basis. In these cases, the presence of repetitive patterns which govern orbital arrangements are becoming evident. See also Generalized Peas-in-a-Pod: Extending Intra-System Mass Uniformity by Armaan Goyal and Songhu Wang at 2206.00053.

The planets within compact multi-planet systems tend to have similar sizes, masses, and orbital period ratios, like "peas in a pod". The smaller "super-Earths" are consistent with being stripped rocky cores, while the larger "sub-Neptunes" likely have gaseous H/He envelopes. Given these consistencies, we test for intra-system uniformity these planetary categories. For example, the sub-Neptunes tend to be 1.7+0.6−0.3 times larger than the super-Earths in the same system.

Millholland, Sarah, et al. Kepler Multi-Planet Systems Exhibit Unexpected Intro-System Uniformity in Mass Radius. arXiv:1710.11152. We cite this entry by Yale University astronomers as an example of how sunny stars with orbital worlds are being found to have their own overall, interactive properties. Just as Caroline Dorn, et al, for example, are treating exoplanets as dynamic units, so entire solar systems seem to possess an integral nature.

The widespread prevalence of close-in, nearly coplanar super-Earth- and sub-Neptune-sized planets in multiple-planet systems was one of the most surprising results from the Kepler mission. By studying a uniform sample of Kepler "multis" with mass measurements from transit timing variations (TTVs), we show that a given planetary system tends to harbor a characteristic type of planet. That is, planets in a system have both masses and radii that are far more similar than if the system were assembled randomly from planets in the population. This finding has two important ramifications. First, the large intrinsic compositional scatter in the planet mass-radius relation is dominated by system-to-system variance rather than intra-system variance. Second, if provided enough properties of the star and primordial protoplanetary disk, there may be a substantial degree of predictability in the outcome of the planet formation process. (Abstract)

Mishra, Lokesh, et al. A Framework for the Architecture of Exoplanetary Systems. I. Four Classes of Planetary System Architecture. arXiv:2301.02374. This is an important, historic paper to appear in Astronomy & Astrophysics because after three decades of myriad revolutionary orbital world findings, University of Bern and Geneva Observatory astronomers including Sterphane Urdy, can report that entire solar orrerys seem to settle into distinct, inherent planetary arrangements. A companion posting at 2301.02373 with a II. Nature versus Nurture: Emergent Formation Pathways of Architecture Classes subtitle describes initial and later protoplanet, metalliticy and other aspects. In more regard, see a news Item Order from Chaos by Lee Billings in Scientific American (May 2023) with a graphic rendition of these salient placings. Along with a notice of constant ecosmic regularities, quite an epochal discovery itself, it is observed that our own system sequence from an inner Mercury to outer gas giants is an uncommon occurrence.

We present a novel, model-independent framework for studying the architecture of exoplanets at its whole system level, which allows us to study and classify its overall character. As a result, we propose that solar-planet systems be partitioned into four classes: similar, mixed, anti-ordered, and ordered. with regard to mass, radius, density, and core water fraction. Our work suggests that global similarities are the most common formation; internal composition of planets shows a strong link with their overall nature; and most anti-ordered systems are expected to be rich in wet planets, while most observed mass ordered systems are expected to have dry planets. We find, in good agreement with theory, that orbital arrays are similar, mixed, or anti-ordered. We also speculate on the role of system architectures in hosting habitable worlds (2301.02374 Abstract)

Morbidelli, Alessandro. Dynamical Evolution of Planetary Systems. Oswalt, Terry and Linda French, eds. Solar and Stellar Planetary Systems. Berlin: Springer, 2013. In this chapter, the Observatoire de la Cote d'Azur, Nice, France astronomer reviews a decade of research across Europe and worldwide due to realizations of a novel universe that is filled with orbital worlds. As the quotes extol, and 2015 citations by Giovanna Tinetti, Elke Pilat-Lohinger and others confirm, some general summations accrue. As the formation of stars and planets becomes understood, these phases proceed in a widely stochastic fashion of eccentric orbits, gas giants and super-Earths running into each other, and so on. In this scenario, it is just dawning that our own solar system exhibits a rare multi-billion year stability, planets lie in the same plane with circular orbits, with an orderly sequence. Here is an epochal discovery that is just dawning. See also Terrestrial Planet formation in the Presence of Migrating Super-Earths (1408.1215) and Chaotic Disintegration of the Inner Solar System (1411.5066), each with Morbidelli as coauthor.

The apparent regularity of the motion of the giant planets of our solar system suggested for decades that said planets formed onto orbits similar to the current ones and that nothing dramatic ever happened during their lifetime. The discovery of extra-solar planets showed astonishingly that the orbital structure of our planetary system is not typical. Many giant extra-solar planets have orbits with semi major axes of ∼ 1 AU, and some have even smaller orbital radii, sometimes with orbital periods of just a few days. Moreover, most extra-solar planets have large eccentricities, up to values that only comets have in our solar system. Why such a big diversity between our solar system and the extra-solar systems, as well as among the extra-solar systems themselves?

In fact, the best explanation for the large orbital eccentricities of extra-solar planets is that the planets that are observed are the survivors of strong instability phases of original multi-planet systems on quasi-circular orbits. The main difference between the solar system and the extra-solar systems is in the magnitude of such an instability. In the extra-solar systems, encounters among giant planets had to be the norm. In our case, the two major planets (Jupiter and Saturn) never had close encounters with each other: they only encountered “minor” planets like Uranus and/or Neptune. This was probably just mere luck, as simulations show that Jupiter-Saturn encounters in principle could have occurred. (Abstract)

This chapter discussed the evolution of planetary systems. The emphasis has been put on the evolution of our solar system. Our team effort, over the last 10 years, has been to reconstruct the history of our system using computer simulations and taking advantage of all possible detailed constraints (the orbits of the planets, the architecture of the populations of small bodies, radioactive chronologies for terrestrial planet formation, crater records etc.). Although imperfect, I think that our view of the evolution of the solar system, since the completion of giant planets formation, has reached a quite satisfactory level of coherence. (40-41)

Morbidelli, Alessandro and Sean Raymond. Challenges in Planet Formation. arXiv:1610.07202. Universite de Nice Sophia-Antipoli, and CNRS, Laboratoire d'Astrophysique de Bordeau astrophysicists provide a latest update about how object worlds might have formed. As we report this active literature, an auspicious realization is that our own solar system is a rarest case (one in a thousand herein) with a relatively benign, long lived conducive order. A philosophical reflection ought to note how incredible it is that a global sapience can look back and reconstruct how this special planet and people came to be.

Over the past two decades, large strides have been made in the field of planet formation. Yet fundamental questions remain. Here we review our state of understanding of five fundamental bottlenecks in planet formation. These are: 1) the structure and evolution of protoplanetary disks; 2) the growth of the first planetesimals; 3) orbital migration driven by interactions between proto-planets and gaseous disk; 4) the origin of the Solar System's orbital architecture; and 5) the relationship between observed super-Earths and our own terrestrial planets. (Abstract)

The origin of planets is a vast, complex and still quite mysterious subject. Despite decades
of space exploration, ground based observations and detailed analyses of meteorites and cometary grains it is still not clear how the planets of the Solar System formed. The discovery of extrasolar planets has added confusion to the problem, bringing to light evidence that planetary systems are very diverse, that our Solar System is not a typical case and that categories of planets that don't exist in our system are common elsewhere (e.g. the super-Earth planets). (2)

Just like any individual person, the Solar System has its own history. The probability of any other planetary system following an identical blueprint is zero. But how typical was the Solar System's evolutionary path? Based on statistically-sound exoplanet observational surveys, the Sun-Jupiter system is special at roughly the level of one in a thousand. First, the Sun is an unusually massive star; the most common type of star are M dwarfs, with masses of 10-50% of the Sun's. Second, only 10% of Sun-like stars have gas giant planets with orbits shorter than a few to 10 AU. Third, only about 10% of giant exoplanets have orbits wider than 1 AU and eccentricities smaller than 0.1. Taken together, these constraints suggest the Sun-Jupiter system is a 0.1% case. The numbers quoted here are a simple order of magnitude, but they clearly illustrate that the Solar System is not a typical case in at least one regard: the presence and orbit of Jupiter. (20)

Morbidelli, Alessandro, et al. Building Terrestrial Planets. Annual Review of Earth and Planetary Science. 40/251, 2012. Universite de Nice-Sophia Antipolis, Cornell University, Planetary Sciences Institute, Tucson, Universite de Bordeaux, and Southwest Research Institute astrophysicists study how disparate orbiting worlds proceed to agglomerate, coalesce and become gaseous or solidify with various liquid and chemical mantles. Isn’t it amazing then, after billions of years, as brave creatures form a collaborative noosphere, we can reconstruct how their earth, and all kinds of potential neighbors come to be? What for, whatever kind of a cosmos, what such great discovery and resolve awaits?

This article reviews our current understanding of terrestrial planet formation. The focus is on computer simulations of the dynamical aspects of the accretion process. Throughout the review, we combine the results of these theoretical models with geochemical, cosmochemical, and chronological constraints to outline a comprehensive scenario of the early evolution of our solar system. Given that the giant planets formed first in the protoplanetary disk, we stress the sensitive dependence of the terrestrial planet accretion process on the orbital architecture of the giant planets and on their evolution. This suggests a great diversity among the terrestrial planet populations in extrasolar systems. Issues such as the cause for the different masses and accretion timescales between Mars and Earth and the origin of water (and other volatiles) on our planet are discussed in depth. (Abstract)

Morbidelli, Alessandro, et al. Formation and evolution of a protoplanetary disk: combining observations, simulations and cosmochemical constraints.. arXiv:2409.06342. A posting by fifteen astronomers in France, Germany, Spain, Taiwan and Japan that as a current status report of our collaborative Earthuman project to explore, reconstruct, quantify and learn how orbital worlds and this home abide originally came to form out of primordial pebble-like accretions. An incredible scenario presents itself in the 2020s whence a late, optimum global sapience can achieve a necessary ecosmic self-description. See also Compositional Outcomes of Earth Formation from a Narrow Ring by Katherine Dale, et al (Morbidelli) at arXiv:2503.19526 for latest views.

We present a plausible and coherent view of the evolution of the protosolar disk that is consistent with the cosmochemical constraints and compatible with observations of other protoplanetary disks and sophisticated numerical simulations. The assumption that the material accreted towards the end of the infall phase was isotopically distinct allows us to explain the observed dichotomy in nucleosynthetic isotopic anomalies of meteorites. In conclusion, the evolution of the protosolar disk seems to have been quite typical in terms of size, lifetime, and dust behavior, suggesting that the peculiarities of the Solar system with respect to the extrasolar planetary system probably originate from the chaotic nature of planet formation and not at the level of the parental disk. (Excerpt)

Mordasini, Christoph, et al. Global Models of Planet Formation. International Journal of Astrobiology. 14/2, 2015. This Exoplanet edition indeed shows how much has been learned in the past few years about a galaxy and cosmos that is now understood as inherently filled with orbital worlds of every possible kind. German, Chinese, and Swiss astronomers can thus propose an initial census of planetary populations. But it is curious that this celestial propensity for solar incubators has not yet been invoked as a cosmic Copernican revolution from a Ptolemaic pointlessness to a natural nursery and heavenly hatchery.

Despite the strong increase in observational data on extrasolar planets, the processes that led to the formation of these planets are still not well understood. However, thanks to the high number of extrasolar planets that have been discovered, it is now possible to look at the planets as a population that puts statistical constraints on theoretical formation models. A method that uses these constraints is planetary population synthesis where synthetic planetary populations are generated and compared to the actual population. The key element of the population synthesis method is a global model of planet formation and evolution. With future global models addressing the geophysical characteristics of the synthetic planets, it should eventually become possible to make predictions about the habitability of planets based on their formation and evolution. (Abstract excerpts)

Moriarty, John and Sarah Ballard. The Kepler Dichotomy in Planetary Disks: Linking Kepler Observables to Simulations of Late-Stage Planet Formation. arXiv:1512.03445. We cite this entry by Yale University and MIT astrophysicists to convey the sophisticated, diverse range of exoplanet and exosolar system studies. Of note is a referral to the Kepler Dichotomy named for optional attractor modes that embryonic orbital worlds may settle into. See also Spin-Orbit Misalignment as a Driver of the Kepler Dichotomy (1607.03999), and A Flat Inner Disk Model as an Alternative to the Kepler Dichotomy in the Q1 to Q16 Planet Population (1702.08126).

NASA's Kepler Mission uncovered a wealth of planetary systems, many with planets on short-period orbits. These short-period systems reside around 50% of Sun-like stars and are similarly prevalent around M dwarfs. Their formation and subsequent evolution is the subject of active debate. In this paper, we simulate late-stage, in-situ planet formation across a grid of planetesimal disks with varying surface density profiles and total mass. We identify mixture models with different primordial planetesimal disk properties that self-consistently recover the multiplicity, period ratio and duration ratio distributions of the Kepler planets.

We draw three main conclusions: (1) We favor a "frozen-in" narrative for systems of short period planets, in which they are stable over long timescales, as opposed to metastable. (2) The "Kepler dichotomy", an observed phenomenon of the Kepler sample wherein the architectures of planetary systems appear to either vary significantly or have multiple modes, can naturally be explained by formation within planetesimal disks with varying surface density profiles. Finally, (3) we quantify the nature of the "Kepler dichotomy" for both GK stars and M dwarfs, and find that it varies with stellar type. While the mode of planet formation that accounts for highly multiplistic systems occurs in 24+/-7% of planetary systems orbiting GK stars, it occurs in 63+/-16% of planetary systems orbiting M dwarfs. (Abstract)

Muresan, Alexandra, et al. Diversities and similarities exhibited by multi-planetary systems and their architectures: I. Orbital spacings.. Astronomy & Astrophysics.. October 27, 2024. Chalmers University of Technology exoplanet scientists give further credence to sunny stars with global orrerys as having a whole scale, integral unity.

The rich diversity of multi-planetary arrays is contrasted by unity within many of these solar systems. Previous studies have shown that compact Kepler versions tend to exhibit a peas-in-a-pod architecture: This work examines larger, diverse sample with at least three planets. We focused on adjacent orbital spacings and the similarities of the sizes, masses, and spacings of planets within each system. Notably, planets in the same system can be similarly spaced even if they do not have similar masses or sizes. (Excerpt)

Naeye, Robert. Planetary Harmony. Sky & Telescope. January, 2005. To date 18 multiple-planet extrasolar systems have been found by astronomers, whose orbital properties bring a new dimension to the understanding of solar systems. There seem to be two general types – if Jupiter size planets are too proximate they tend to scatter smaller planets into wide elliptical orbits not conducive for life. But if their spacing is similar to our own solar system, a resonant condition sets in between large and small planets favorable for life and its temporal evolution. See also an article "Pictured at Last?" by Naeye in the August 2005 issue of the same journal which talks about advanced telescopes and computer enhancements which make it a matter of time until exoplanets can be visually seen.

Ollivier, Marc, et al. Planetary Systems: Detection, Formation, and Habitability of Extrasolar Planets. Berlin: Springer, 2009. A profoundly new kind of fertile cosmos is being revealed in our midst as earthkind her/his self proceeds to seek out and find an increasing natural propensity for and presence of orbital worlds.

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