III. Ecosmos: A Revolutionary Fertile, Habitable, Solar-Bioplanet Incubator Lifescape
H. Prolific ExoWorlds, Galactic Dynamics, Solar Orrerys, Habitable Zones, Biosignatures
Quintana, Elisa, et al. An Earth-Sized Planet in the Habitable Zone of a Cool Star. Science. 344/277, 2014. A 23 member premier team from NASA, universities, and institutes in the US and France, including Jack Lissauer, find the best candidate so far (April) for a real Earth analog. An editorial Almost-Earth Tantalizes Astronomers with Promise of Worlds to Come cites “a wide new hunting found for extraterrestrial life.” And it is notable to see solar systems now commonly depicted with such habitable bands.
The quest for Earth-like planets is a major focus of current exoplanet research. Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces. We present the detection of Kepler-186f, a 1.11 ± 0.14 Earth-radius planet that is the outermost of five planets, all roughly Earth-sized, that transit a 0.47 ± 0.05 solar-radius star. The intensity and spectrum of the star’s radiation place Kepler-186f in the stellar habitable zone, implying that if Kepler-186f has an Earth-like atmosphere and water at its surface, then some of this water is likely to be in liquid form. (Abstract)
Ramirez, Ramses. A More Comprehensive Habitable Zone for Finding Life on Other Planets. Geosciences. Online July, 2018. A contribution to a Planetary Evolution and Search for Life on Habitable Planets special issue, edited by Lena Noack and Ralf Moeller, by an Earth-Life Science Institute, Tokyo University astrophysicist. As our whole Earthkind exoplanet census project rapidly takes off, many papers like this seek better definitions and understandings of hospitable solar and galactic areas for living systems to form, evolve, and maybe reach a global intelligence. Similar to Del Genio, et al above, the fates of Venus and Mars are a good start. Stellar main-sequences, greenhouse gases and relative oxygen levels are further factors.
A contribution to a Planetary Evolution and Search for Life on Habitable Planets special issue, edited by Lena Noack and Ralf Moeller, by an Earth-Life Science Institute, Tokyo University astrophysicist. As our whole Earthkind exoplanet census project rapidly takes off, many papers like this seek better definitions and understandings of hospitable solar and galactic areas for living systems to form, evolve, and maybe reach a global intelligence. Similar to Del Genio, et al above, the fates of Venus and Mars are a good start. Stellar main-sequences, greenhouse gases and relative oxygen levels are further factors.
Raymond, Sean and Alessandro Morbidelli. Planet Formation: Key Mechanisms and Global Models. arXiv:2002.05756. As global capabilities to explore and quantify a increasing array of eclectic orbital worlds and to reconstruct how they came to form, veteran astrophysicists (search) at the University of Bordeaux and the Cote d’Azur Observatory, Nice post a 103 page, 372 reference copious paper upon the latest findings. It opens with a graphic about Earth and Jupiter which cites dust coagulation, pebble accretion, planetismals, giant impacts, moon making and more and goes on about the masses and orbits of super-Earths, cosmo-chemical growth factors, asteroid compositions, and every other aspect. An impression grows of how wildly stochastic the long, dramatic course of solar systems actually is, which then highlights our own Earth whence a collaborative species is able to achieve its consciously perceived description.
In order to make sense of the origin of the planets we must first understand the origin of their building blocks. The first part presents a detailed description of six key mechanisms of planet formation: 1) The structure and evolution of protoplanetary disks, 2) The formation of planetesimals, 3) Accretion of protoplanets, 4) Orbital migration of growing planets, 5) Gas accretion and giant planet migration, and 6) Resonance trapping during planet migration. The second part of this review shows how global models are built out of planet formation processes by explaining different populations of known planetary systems, including close-in small/low-mass planets (i.e., super-Earths), giant exoplanets, and the Solar System's planets. We discuss the different sources of water on rocky exoplanets, and use cosmochemical measurements to quantify the origin of Earth's water. (Abstract excerpt)
Raymond, Sean, et al. Exotic Earths: Forming Habitable Worlds with Giant Planet Migration. Science. 1414/313, 2006. Within the rush of findings about planet formation, diversity, and movements, the prevalence and role of “hot Jupiters” is contributing to how solar systems contain Earth-like, water and land bearing objects.
Reich, Eugenie Samuel. Beyond the Stars. Nature. 470/24, 2011. Apropos, I caught on C-Span TV a NASA media day (February 1) on the first findings of its Kepler Spacecraft Search for Habitable Planets. Lead scientist Jack Lissauer of NASA Ames, and Yale astronomer Debra Fischer, could hardly contain their excitement about its breakthrough advance beyond Doppler methods which could only detect Jupiter size worlds. As a companion article “A Closely Packed System of Low-Mass, Low-Density Planets Transiting Kepler-11” in the issue (470/53) reports, orbiting this Sun-like star are not only six large objects but five smaller earth-like planets. Launched in March 2009, the mission has exceeded expectations, and as these early results promise, appears to fulfill the historical dream of encountering a friendly cosmos sown with life-hospitable worlds. An illustrated New York Times story by Dennis Overbye “Gazing Afar for Other Earths, and Other Beings” on January 31 further conveys the exhilaration.
What makes this so striking is the satellite’s instruments always point at the same tiny arc of the Milky Way near the constellation called the Northern Cross — only one four-hundredth of the sky. The Kepler team leader, William Borucki, at the Ames Research Center in Northern California, says that if Kepler could see the whole sky, it would have found some 400,000 planets. (NY Times editorial February 7, 2011)
Rodet, Laetita, et al. ODEA: Orbital Dynamics in a Complex Evolving Architecture. arXiv:1909.04536. We cite this entry by University of Grenoble, Stanford University and UC Berkeley researchers as an example of analytic methods such as symplectic integrators being applied even to exoplanetary solar systems. ODEA stands for an algorithm they developed for this purpose. In regard, a take away may be that even heavenly spheres do indeed dance and move to a mathematical score.
Sage, Leslie. Exoplanets. Nature. 513/327, 2014. An introduction to a special collection as this celestial spacescape of neighbor worlds increasingly beckons. A main paper is Advances in Exoplanet Science from Kepler by Jack Lissauer, Rebekah Dawson, and Scott Tremaine. See also Exoplanets by Adam Burrows and Geoffrey Marcy in PNAS. herein for a similar, concurrent survey.
Sandford, Emily, et al. On Planetary Systems as Ordered Sequences. arXiv:2105.09966. Astrophysicists ES, Cavendish Laboratory, UK and David Kipping, Columbia University, along with computer scientist Michael Collins, Columbia U. post an overview perception just now possible as myriad worlds are detected across the galaxy. After Gilbert & Fabrycky 2020, it is proposed that entire solar systems ought to be viewed as a unitary network arrangement due to geometric and mathematic patternings. We note this appreciation necessarily implies an intrinsic ecosmic reality.) A further advance is the use of computational linguistics via natural language processing to identify a textual quality. By this extension to planetary objects and host stars, a working analogy is achieved by way of word-like worlds and grammatical conventions that they may express. The paper explains how suitable this identity and correspondence appears to be for all manner and classifications of stellar forms and globular groupings. By this historic synthesis, as sunny stars and orbital orrerys may become the primary ecosmic formation they can take on semblance of an inscribed literary narrative. The 25 page contribution has been accepted by the Monthly Notices of the Royal Astronomical Society.
A planetary system consists of a host star and one or more planets, arranged into a particular configuration. Here, we consider what information belongs to the configuration, or ordering, of 4286 Kepler planets in their 3277 planetary systems. First, we train a neural network model to predict the radius and period of a planet based on the properties of its host star and the radii and period of its neighbors. Second, we adapt a model used for unsupervised part-of-speech tagging in computational linguistics to investigate whether planets or planetary systems fall into natural categories with physically interpretable "grammatical rules." The model identifies two robust groups of planetary systems: (1) compact multi-planet systems and (2) systems around giant stars, although the latter group is strongly sculpted by the selection bias of the transit method. These results reinforce the idea that planetary systems are not random sequences -- instead, as a population, they contain predictable patterns that can provide insight into the formation and evolution of planetary systems. (Abstract)
Sasselov, Dimitar. How We Found Hundreds of Potential Earth-Like Planets. http://www.ted.com/talks/dimitar_sasselov_how_we_found_hundreds_of_potential_earth_like_planets. Circa 2102 the count is into many thousands. A July 2010 TED talk by the Harvard University astronomer and director of the Harvard Origins of Life Initiative who expands on findings by the Kepler Telescope within a novel, imaginative cosmic context. The Copernican revolution of earth orbiting the sun is often seen as starting a long demotion of human centrality that is now engulfed by an abysmal multiverse. But Sasselov reminds that in the 16th century it was conjectured that if home Earth circled a star, then the starry heavens ought to similarly be filled with companion worlds. This alternative view is at last fulfilled: “The galaxy is rich in small, Earth-like planets.” By these lights and vista, as his concluding quotes affirm, life and persons are actually of vast, unrealized importance and promise, if we can just save precious earth for such a creative destiny. See also Sasselov’s January 2012 book Life of Super-Earths: How the Hunt for Alien Worlds and Artificial Cells Will Revolutionize Life on Our Planet.
The universe and life are both in space and time. If that was the age of the universe, then this is the age of life on Earth. Think about those oldest living things on Earth, but in a cosmic proportion. This is not insignificant. This is very significant. So life might be insignificant in size, but it is not insignificant in time. Life and the universe compare to each other like a child and a parent, parent and offspring.
Scharf, Caleb. Extrasolar Planets and Astrobiology. Sausalito, CA: University Science Books, 2009. When a realm of celestial objects, first definitively viewed only in 1995, can merit an excellent, thorough textbook then a certain maturity has been reached. As Director of the Columbia University Astrobiology Center, Scharf dutifully covers all aspects of planetary composition, various atmospheres, habitable zones, prebiotic cosmochemistry, and so on. And it would seem that the implications of such a novel filling in of the cosmic neighborhood, similar to the finding of myriad galaxies in the 1920s and 1930s, has not yet registered. For it reveals a cosmos which by its innate nature spawns a prolific expanse of earth-like abodes for life to generate complex and conscious forms. In the final pages, Scharf indeed broaches a view quite at odds with the current mechanical model, in so many words that an organic genesis universe is being found with its own essence and destiny.
At the start of the book, we posited that life is a phenomenon that emerges in this Universe as naturally as physical “laws,” such as Newtonian gravity. It certainly seems that many of the pieces that go together to enable life as we know it are indeed inevitable. Star and planet formation, and complex carbon chemistry, are generic features of the cosmos, and these appear to be critical for life. (450)
Schneider, Jean, et al. The Far Future of Exoplanet Direct Characterization. Astrobiology. 10/1, 2010. Some 21 space scientists from across Europe and the U. S. look ahead to at last being able, conceivably, meet cousin creatures on other companion worlds.
We describe future steps in the direct characterization of habitable exoplanets subsequent to medium and large mission projects currently underway and investigate the benefits of spectroscopic and direct imaging approaches. We show that, after third- and fourth-generation missions have been conducted over the course of the next 100 years, a significant amount of time will lapse before we will have the capability to observe directly the morphology of extrasolar organisms. (Abstract, 121)
Seager, Sara. Exoplanet Atmospheres: Physical Processes. Princeton: Princeton University Press, 2010. The MIT astronomer provides the first book length treatment of a subject hardly imaginable until just now, via the epochal discovery of an organic cosmos filled with habitable worlds. A chapter with this title by the author and Drake Deming can be found in the Annual Review of Astronomy and Astrophysics (48/631, 2010).
Over the past twenty years, astronomers have identified hundreds of extrasolar planets--planets orbiting stars other than the sun. Recent research in this burgeoning field has made it possible to observe and measure the atmospheres of these exoplanets. This is the first textbook to describe the basic physical processes--including radiative transfer, molecular absorption, and chemical processes--common to all planetary atmospheres, as well as the transit, eclipse, and thermal phase variation observations that are unique to exoplanets. (Publisher website)