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

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

Lammer, Helmut and Maxim Khodachenko, eds. Characterizing Stellar and Exoplanetary Environments. Berlin: Springer, 2015. As the synopsis notes, this volume edited by Austrian Space Research Institute scientists expands the human horizon to a deeply welcoming cosmos spacescape. A closing chapter is Living with Stars: Future Space-Based Exoplanet Search and Characterization Missions.

In this book an international group of specialists discusses studies of exoplanets subjected to extreme stellar radiation and plasma conditions. It is shown that such studies will help us to understand how terrestrial planets and their atmospheres, including the early Venus, Earth and Mars, evolved during the host star’s active early phase. The book presents an analysis of findings from Hubble Space Telescope observations of transiting exoplanets, as well as applications of advanced numerical models for characterizing the upper atmosphere structure and stellar environments of exoplanets. The book is divided into four main parts, grouping chapters on exoplanet host star radiation and plasma environments, exoplanet upper atmosphere and environment observations, exoplanet and stellar magnetospheres, and exoplanet observation and characterization. The book closes with an outlook on the future of this research field.

Lammer, Helmut, et al. What Makes a Planet Habitable? Astronomy and Astrophysics Review. 17/2, 2009. Some 15 senior members of the European astrospace community from Austria, Germany, France, Holland, Sweden, England, and onto Russia and the US, provide an extensive review of a galaxy and cosmos seemingly rift with worlds of every kind, as the Abstract notes. As these many studies express, an innately conducive milieu of solar systems, suitable biospheres, earth-analogs, seems increasingly evident. The paper agrees that life’s origin requires the common minimum of a membrane vesicle, metabolic proteins, and an information carrier, along with a driving energy gradient.

This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life. (Abstract)

Laughlin, Gregory and Jack Lissauer. Exoplanetary Geophysics: An Emerging Discipline. Schubert, Gerald, ed.. Treatise on Geophysics. Amsterdam: Elsevier, 2015. A chapter for this 11 volume, 2nd edition by UC Santa Cruz, and NASA Ames scientists as terrestrial studies can now be extended to a galactic and cosmic scale. Who are we Earthlings to be the universe's way of describing and comprehending itself?

Lemonick, Michael. Can We Find Another Earth? Discover. March, 2002. The rapid progress in detecting stars with orbiting planets by perturbations in their movement due to the orbiting bodies, now over 100, leads to plans for telescopes able to focus in from Jupiter to Earth size globes.

Lemonick, Michael. Mirror Earth: the Search for Our Planet’s Twin. New York: Walker, 2012. Once science editor at Time magazine, the prolific author engagingly presents the incredible project and promise of finding another earth-like habitable world, which are now expected to abound across galaxy and cosmos. This is accomplished through vignette interviews with proponents such as William Borucki, Geoff Marcy, Dimitar Sasselov, David Charbonneau, and especially “female exoplaneteers” Natalie Batalha, Deborah Fisher, and Sara Seager. The abiding scenario and incentive is a fertile universe whereof bioworlds and evolutionary life flourishes. As an aside, I found this on the new book shelf at the Integrated Science and Engineering Library, University of Massachusetts at Amherst next to Destiny or Chance Revisited: Planets and their Place in the Cosmos by Stuart Taylor (Cambridge UP, 2012) which opts for the negative “rare Earth” view, now mostly discredited, of a forbidding spacescape where inhabited worlds are extreme accidents (which as usual says more about the writers).

Lin, Wen-Xu et al. Decoding the Future of Exoplanets: Asteroseismic Confirmation of Subgiant and Red Giant Hosts.. arXiv:2411.14703. Eight Yunnan University, Kunming, and University of Chinese Academy of Sciences, Beijing propose that exoworld characterizations would benefit if this significant property of relative seismic activity could be studied and factored in

Asteroseismology has become a powerful tool to unravel the actual relationships between evolved stars and their planetary systems. In this study, we investigate the evolutionary stages of five exoplanet host stars which exhibit solar-like oscillations. By measuring asteroseismic parameters such as the period spacing of dipole gravity modes (ΔΠ1), we confirm these stars' evolutionary states as subgiants or RGB stars. This research highlights the profound role of asteroseismology in advancing our knowledge of planetary system evolution and opens new pathways for exploring how stellar evolution impacts planetary survival. (Excerpt)

Lineweaver, Charles and Aditya Chopra. The Habitability of Our Earth and Other Earths: Astrophysical, Geochemical, Geophysical, and Biological Limits on Planet Habitability. Annual Review of Earth and Planetary Sciences. Volume 40, 2012. An Australian National University astrophysicist and a geologist offer an extensive chapter that summarizes these epochal advances of the past decade. The result is the discovery of an expansive array of habitable zones from earth’s crust to galactic neighborhoods. By any measure, our collaborative humankind is presently coming upon a profoundly life, sentience, and people bearing genesis universe.

For life forms like us, the most important feature of the Earth is its habitability. Understanding habitability and using that knowledge to locate the nearest habitable planet may be crucial for our survival as a species. Over the past decade, expectations that the universe could be filled with habitable planets have been bolstered by the increasingly large overlap between terrestrial environments known to harbor life and the variety of environments on newly detected rocky exoplanets. The inhabited and uninhabited regions on Earth tell us that temperature and the presence of water are the main constraints can be used in a habitability classification scheme for rocky planets. Our compilation and review of recent exoplanet detections suggests that the fraction of stars with planets is 100%, and that the fraction with rocky planets may be comparably large. We review extensions to the circumstellar habitable zone including an energy habitable zone to start and maintain life, and the galactic habitable zone. (Abstract)

The increasingly large overlap between terrestrial environments known to harbor life and the surface environments of newly detected rocky exoplanets bolsters expectations that the universe may be filled with habitable planets. The fraction of stars with planets is approximately 100%. The fraction of stars with a rocky planet in the HZ could be comparably large. The water content of rocky planets is highly variable. This variability can be used to classify their habitability, e.g., ocean planets, Earth-like planets, and desert planets. (Summary Points)

Lissauer, Jack. Extrasolar Planets. Nature. 419/355, 2002. A news report about a galaxy and cosmos becoming filled with detectable planetary objects.

Natural philosophers have speculated on the existence of world around other suns for millennia. Now that real data are available, we find a diversity far beyond that expected by scientists, or science-fiction writers. (355)

Lissauer, Jack and Imke de Pater. Fundamental Planetary Science: Physics, Chemistry and Habitability. Cambridge: Cambridge University Press, 2014. It is a good sign that a novel scientific endeavor and subject area has come of age when a comprehensive text can be written about it. Lissauer, NASA Kepler project senior scientist, and de Pater, UC Berkeley and Delft University, situate a wealth of worlds in a conducive cosmos from Astrophysics and Atmospheres to Solar and ExoPlanetary Formation, Dynamics, Surfaces, Interiors, Moons, Comets, Meteors, Rings, and the Life that originated and arose to altogether be able to do this. But an implied Copernican revolution to an innately planet making universe, as so many ovular earths, has not yet occurred.

Lisse, Carey, et al. Abundant Circumstellar Silica Dust and SiO Gas Created by a Giant Hypervelocity Collision in the ~12 Myr HD172555 System. Astrophysical Journal. 701/2019, 2009. A team of astronomers using NASA’s Spitzer Space Telescope has found this evidence of a collision between a larger, Mercury size, and a smaller, Moon like object, which is then seen to imply how our earth formed by a similar impact. We cite as one example in this weekly, telephone-book size, periodical by thousands of researchers of humankind’s sentient surveillance and reconstruction of its galactic and cosmic environs, as if a planetary person.

Livesey, Joseph and Juliette Becker. Secular Perturbations from Exterior Giants Influence Gap Complexity in Peas-in-a-Pod Exoplanetary Systems. arXiv:2412.18661. As solar systems become amenable to study as whole integral units, in regard University of Wisconsin astronomers evaluate how small inner and large outer orbital movements dynamically influence the spacings between them. Over million and billion year eons, stellar orrerys are found to constantly rearrange themselves, which also can then radically effect habitability conditions.

It has been found that systems of tightly packed inner planets with giant exterior companions tend to have less regular orbital spacings than those without such globes. We investigate whether this increase in gap complexity can be explained by the disturbing potential of the outer companions. Amplification of mutual orbital inclinations may lead to the inner system attaining non-mutually transiting geometries that result in a higher gap complexity. We find that these interactions can significantly contribute to this dichotomy in tightly packed multiple-planet systems. (Excerpt)

Planets typically have similar masses to those of their neighbors, and pairs of exoplanets tend to have similar orbital separations to the pairs next to them. This trend of regular spacings and similar masses was identified by (Lauren) Weiss et al. (2018), who named it a “peas in a pod” version. This array is prevalent among transiting exoplanetary systems and has been proposed as the favored outcome of planet formation as well as a natural consequence of dynamical evolution. (1)

Lucarini, Valerio, et al. Habitability and Multistability in Earth-like Planets. Astronomische Nachrichten. 334/6, 2013. With the Kepler satellite now having found a galaxy filled with orbital worlds, University of Hamburg, Germany, physicists are able, with colleagues worldwide and facilitated by 21st century instrumentation and computation, to begin to characterize their (bio)chemical atmospheres and weather dynamics. See also Bistability of the Climate around the Habitable Zone: A Thermodynamic Investigation by Lucarini, et al, in Icarus (226/1724, 2013). And significantly, as recorded in Global Climate as a Complex Dynamic System, this same team is also applying these skills and perceptions to better study and understand our own Earth weather.

We explore the potential multistability of the climate for a planet around the habitable zone. We focus on conditions reminiscent to those of the Earth system, but our investigation aims at presenting a general methodology for dealing with exoplanets. We provide a thorough analysis of the non-equilibrium thermodynamical properties of the climate system and explore, using a flexible climate model, how such properties depend on the energy input of the parent star, on the infrared atmospheric opacity, and on the rotation rate. It is possible to reproduce the multi-stability properties reminiscent of the paleoclimatologically relevant snowball (SB) - warm (W) conditions. These results have relevance for the general theory of planetary circulation and for the definition of necessary and sufficient conditions for habitability. (Abstract excerpt)

Astronomische Nachrichten (Astronomical Notes) is the oldest astronomy journal in publication, first appearing in 1823. It is based at the Leibniz Institute for Astrophysics in Potsdam, and online with Wiley where every issue, with some interruptions, can be accessed. In its worldwide venue it is said to cover “all fields of astrophysical research including instrumentation, numerical methods, solar and stellar astrophysics, extra galactic and cosmological research.”

[Prev Pages]   Previous   | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16  Next  [More Pages]