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

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

Perryman, Michael. Resource Letter Exo-1: Exoplanets. American Journal of Physics. 82/6, 2014. The Princeton University astrophysicist and author of The Exoplanet Handbook provides an extensive overview and tutorial with many online and paper references.

Perryman, Michael. The Exoplanet Handbook. Cambridge: Cambridge University Press, 2018. The British astrophysicist based at the European Space Agency posts this 950 page second edition of his 2011 volume which is a most comprehensive technical reference to date. He is in the midst of active research, see Gaia Radial Velocity Spectrometer at arXiv:1804.09369.

Petigura, Erik, et al. A Plateau in the Planet Population below Twice the Size of Earth. Astrophysical Journal. 770/1, 2013. As the Abstract details, Petigura and Geoffrey Marcy, UC Berkeley, and Andrew Howard, University of Hawaii, have come upon in the latest analysis of the vast Kepler satellite data repository what seems to be a preferred zone of orbital earth analog dimensions.

We carry out an independent search of Kepler photometry for small transiting planets with sizes 0.5-8.0 times that of Earth and orbital periods between 5 and 50 days, with the goal of measuring the fraction of stars harboring such planets. We use a new transit search algorithm, TERRA, optimized to detect small planets around photometrically quiet stars. We restrict our stellar sample to include the 12,000 stars having the lowest photometric noise in the Kepler survey, thereby maximizing the detectability of Earth-size planets. We report 129 planet candidates having radii less than 6 RE found in three years of Kepler photometry (quarters 1-12). We gather Keck HIRES spectra for the majority of these targets leading to precise stellar radii and hence precise planet radii. We make a detailed measurement of the completeness of our planet search. We inject synthetic dimmings from mock transiting planets into the actual Kepler photometry. We then analyze that injected photometry with our TERRA pipeline to assess our detection completeness for planets of different sizes and orbital periods. We compute the occurrence of planets as a function of planet radius and period, correcting for the detection completeness as well as the geometric probability of transit, R /a. The resulting distribution of planet sizes exhibits a power law rise in occurrence from 5.7 RE down to 2 RE , as found in Howard et al. That rise clearly ends at 2 RE . The occurrence of planets is consistent with constant from 2 RE toward 1 RE . This unexpected plateau in planet occurrence at 2 RE suggests distinct planet formation processes for planets above and below 2 RE . (Abstract)

Petigura, Erik, et al. Prevalence of Earth-Size Planets Orbiting Sun-Like Stars. Proceedings of the National Academy of Sciences. Online November, 2013. Petigura and Geoffrey Marcy, UC Berkeley, and Andrew Howard, University of Hawaii, post an epochal report, worthy of front page news, about the spectacular findings of the Kepler satellite, along with worldwide computational and instrumental collaborations, which confirm that our encompassing universe, by intrinsic physical properties, is actually rife with as many planetary objects as stars. In regard, the preferred celestial system appears to be an incubator sun with habitable zones for orbital bioworlds. The New York Times article of November 5, 2013 is “Far-Off Planets Like the Earth Dot the Galaxy” by Dennis Overbye. Search each author above for more papers.

A major question is whether planets suitable for biochemistry are common or rare in the universe. Small rocky planets with liquid water enjoy key ingredients for biology. We used the National Aeronautics and Space Administration Kepler telescope to survey 42,000 Sun-like stars for periodic dimmings that occur when a planet crosses in front of its host star. We found 603 planets, 10 of which are Earth size and orbit in the habitable zone, where conditions permit surface liquid water. We measured the detectability of these planets by injecting synthetic planet-caused dimmings into Kepler brightness measurements. We find that 22% of Sun-like stars harbor Earth-size planets orbiting in their habitable zones. The nearest such planet may be within 12 light-years. (Petigura Significance)

The known odds of something — or someone — living far, far away from Earth improved beyond astronomers’ boldest dreams on Monday. Astronomers reported that there could be as many as 40 billion habitable Earth-size planets in the galaxy, based on a new analysis of data from NASA’s Kepler spacecraft. One out of every five sunlike stars in the galaxy has a planet the size of Earth circling it in the Goldilocks zone — not too hot, not too cold — where surface temperatures should be compatible with liquid water. (Overbye)

Pilat-Lohinger, Elke. The Role of Dynamics on the Habitability of an Earth-like Planet. International Journal of Astrobiology. 14/2, 2015. In an Exoplanet issue, a University of Vienna astrophysicist reaches a notable conclusion about our own solar system. It seems especially conducive because the orbital planets all lie in the same plane, and have basically circular orbits. Such a relative stability over a long time period is most favorable for a suitable biosphere upon which life can evolve and emerge to a noosphere able to observe itself and a planetary neighborhood.

Pudritz, Ralph, et al, eds. Planetary Systems and the Origins of Life. Cambridge: Cambridge University Press, 2007. Earth via humankind (earthkind) in retrospect learns how it (she/he) vicariously came to form and evolve from protoplanetary disks to animate, sentient vitality.

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.

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