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

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

Seager, Sara. The Search for Habitable Planets with Biosignature Gases Framed by a ‘Biosignature Drake Equation.’. International Journal of Astrobiology. Online May, 2017. The MIT astrobiologist continues her frontier project to finesse ways to better evaluate the life-bearing state of myriad exoplanets which are constantly being found. Some 50 years on, the Drake equation (search Vakoch) is thus modified to express the degrees of atmospheric conductivity for living, evolutionary organisms.

The discovery of thousands of exoplanets in the last two decades has uncovered a wide diversity of planets that are very different from those in our own Solar System. Ideas for how to detect signs of life in the variety of planetary possibilities, by way of biosignature gases, are expanding, although they largely remain grounded in study of familiar gases produced by life on Earth and how they appear in Earth's spectrum as viewed as an exoplanet. What are the chances we will be able to observe and identify biosignature gases on exoplanets in the coming two decades? I review the status of the search for habitable planets and biosignature gases framed by a ‘Biosignature Drake Equation’. (Abstract)

Seager, Sara, ed. Exoplanets. Tucson: University of Arizona Press, 2010. Synoptic chapter by leading contributors cover the many subjects of this grand revision as to what kind of celestial spacescape we persons might awaken to. But within a multiverse scheme that prohibits anything at all going on, with life and mind a merest patina, we have not begun to appreciate this discovery of a placental cosmos that innately seeds itself with myriad ovular worlds. An Introduction by Seager and Jack Lissauer gives a good entry to our Earth’s early amazement with a galaxy and cosmos seemingly filled with siblings and neighbors.

The discovery of exoplanets is arguably the greatest scientific revolution since the time of Copernicus. Simply stated, humanity now knows for the first time as a scientific fact: there actually are planets around other stars. (Richard Binzel, Space Sciences Series Editor)

Seager, Sara, organizer, moderator. The Next 40 Years of Exoplanets. http://seagerexoplanets.mit.edu/next40years.htm. Full video talks can be found here from this May 27, 2011 event at MIT where advocates and researchers waxed on this grand vista just opening for our intelligent, technological world. But all is not well in this endeavor. Pioneer finder Geoff Marcy denounced NASA cuts of future search projects, due much to a myopic, pinched bureaucracy. Anyway, speakers such as David Charbonneau, Vikki Meadows “A Futuristic Virtual Planetary Laboratory,” Shawn Murphy, Natalie Batalha, Dimitar Saselov “Life, the Universe, and Everything,” William Bains “New Life and New Civilizations,” and others extoled many promising pathways. The meeting was covered in Science for August 19, 2011 as “A Distant Glimpse of Alien Life?”

Setiawan, Johny, et al. A Giant Planet Around a Metal-Poor Star of Extragalactic Origin. Science. December 17, 2010. A European Space Agency team reports the first sighting of an extrasolar globe that appears to have initially come from beyond our local galaxy. Another significant indicator is registered of our Earth’s epochal discovery of a different kind of cosmos that innately seeds itself with such myriad potentially ovular worlds.

Because HIP 13044 belongs to a group of stars that have been accreted from a disrupted satellite galaxy of the Milky Way, the planet most likely has an extragalactic origin. (1642)

Seyler, Lauren, et al. Metabolomics as an Emerging Tool in the Search for Astrobiologically Relevant Biomarkers. Astrobiology. June, 2020. A seven member team from the Woods Hole Oceanographic Institution, Centro de Astrobiología, Madrid, Blue Marble Space Institute, Seattle, and Cal Tech including James Cleaves scope out how such an expansive –omics approach, properly integrated and applied, can well facilitate this grand new exoplanetary phase as Earthlings begin to search for near and far celestial neighbors.

It is now easy to sequence and recover microbial genomes from environmental samples. If transcriptional and translational functions can be assigned to these genomes, it should be possible to understand the molecular inputs and outputs of a microbial community. However, gene-based tools alone are presently insufficient to describe the full suite of chemical reactions and small molecules that compose a living cell. Metabolomic tools have developed quickly and now enable rapid detection and identification of small molecules within biological and environmental samples. These technologies will soon facilitate the detection of novel enzymatic activities, novel organisms, and potentially extraterrestrial life-forms. (Abstract)

Shahar, Anat, et al, Anat, et al. What Makes a Planet Habitable. Science. 364/434, 2019. Carnegie Institute of Washington geochemists add another requirement for life’s long-term viability. Suitable internal core conditions are a vital factor within the overall conduciveness for living systems to appear and evolve.

The Milky Way Galaxy teems with planetary systems, most of which are unlike our own. It is tempting to assume that life can only originate on a planet that is similar to Earth, but different planets able to sustain Earth-like features could be important for habitability studies. To aud the search for extraterrestrial life, scientists must assess which features of Earth are essential to the development and sustenance of life for billions of years and whether the formation of such planets is common. External effects such as stellar variability and orbital stability affect habitability, but internal processes that sustain a clement surface are also vital. A combination of observations, experiments, and modeling of planetary interiors can guide the search for extraterrestrial life. (Summary)

Shibata, Sho and Andre Izidoro. Formation of super-Earths and mini-Neptunes from rings of planetesimals.. arXiv:2501.03345. Earth, Environmental and Planetary Sciences, Rice University astroscientists describe the presence of what is now seen as common interactivity between these disparate candidates.

The solar system planetary architecture has been proposed to be consistent with the terrestrial and giant planets forming from material rings. Here, we show that super-Earths and mini-Neptunes may share a similar formation pathway. In our simulations, super-Earths accrete from rocky material rings in the inner disk. Mini-Neptunes originate from rings beyond the water snowline via pebble accretion. Our results predict that planets at ~1 au in systems with close-in super-Earths and mini-Neptunes are water-rich. (Excerpt)

Shields, Aomawa. The Climates of Other Worlds: A Review of the Emerging Field of Exoplanet Climatology. Astrophysical Journal Supplement Series. 243/2, 2019. A UC Irvine astrophysicist adds another important detectable feature for exoplanet searches across near and far Milky Way environs. Just as here, atmospheric weather patterns are a good indicator of relative habitability.

While climate models have often used to analyze and predict climate and weather on Earth, a growing community of researchers has begun to apply relative models to extrasolar planets. This work has provided a better understanding of how orbital, surface, and atmospheric properties affect planetary climate and habitability; how these climatic effects might change for different stellar and planetary environments; and how observational signatures of newly discovered planets might be influenced by these climatic factors. This review summarizes the active field of exoplanet climatology thus far, recent work using a hierarchy of computer models to identify planets most capable of supporting life, and offers a glimpse into future directions for exoplanet science. (Abstract excerpt)

Shorttle, Oliver, et al. Why Geosciences and Exoplanetary Sciences Need Each Other. arXiv:2108.08382. In an article to appear in a special Geoscience Beyond the Solar System issue (17/4) of Elements: An International Magazine of Mineralology, Geochemistry and Petrology, Cambridge University and Southwest Research Institute astrogeologists including Cayman Unterborn contribute to this grand project going forward as our fittest global genius begins to explore and quantify near and farther orbital environs. A glossary from Abiogenesis Zone and Albedo to Tidal Lock and White Dwarf suits the wild frontier. See also Compositional Diversity of Rocky Exoplanets at 2108.08383, and The Diversity of Exoplanets: From Interior Dynamics to Surface Expressions st 2198L09385, for this issue. See Blue Marble, Stagnant Lid: Could Dynamic Topography avert a Waterworld? by this group at 2201.05636 for more considerations.

The study of planets outside our solar system may lead to major advances in our understanding of the Earth, and provide insight into the universal set of rules by which planets form and evolve. To achieve these goals requires applying geoscience's wealth of Earth observations to fill in the blanks left by the necessarily minimalist exoplanetary observations. In turn, Earth's many one-offs, e.g., plate tectonics, surface liquid water, a large moon, and life - which have long presented chicken and egg type conundrums for geoscientists - may find resolution in the study of exoplanets possessing only a subset of these phenomena. (Abstract)

Shostak, Seth. Searching for Smart Life around Small Stars. Astronomy. February, 2014. The SETI Institute astronomer and advocate contends that “red dwarfs” ought to be an especially favorable locale for bioworlds with intelligence. Article illustrations go on to depict a Residential Areas around a G type stars (our sun) and this K type, dubbed No Fry Zones or habitable areas. But by displaying both a planetary band and the host star, one is led to wonder if they altogether are “solar incubator” systems, which would be conceivable from a revolutionary conducive spacescape, heavenly hatchery, vista. See How Did Life Begin? by SS in The Search for Alien Life issue from Scientific American (Summer 2022).

A red dwarf is a small and relatively cool star on the main sequence, either late K or M spectral type. Because of their small size, they burn their fuel slowly, which allows them to live a very long time. (Internet)

Sibony, Yves, et al. The Rotation of Planet-Hosting Stars. arXiv:2204.01421. University of Geneva and University of Zurich researchers perform initial analyses that indicate the presence of whole solar system interactivities between physical stellar forces and nascent orbital worlds.

Simpson, Fergus. An Anthropic Prediction for the Prevalence of Waterworlds. arXiv:1607.03095. As myriad orbital objects of every possible kind are being detected, the University of Barcelona, Institute for Cosmic Sciences, researcher notes that in contrast to a default state of wholly wet or dry surfaces, Earth’s mottled mantle of ocean and land is a rare anomaly. By way of a “planetary fecundity,” life has been able to evolve from primitive rudiments to human observers, thus an anthropic explanation. We include longish quotes to catch the gist, which appends another reason why this home Earth is so uniquely precious.

Should we expect most habitable planets to share the Earth's marbled appearance? Terrestrial planets within the habitable zone are thought to display a broad range of water compositions, due to the stochastic nature of water delivery. Such diversity, taken at face value, implies that the surfaces of most habitable planets will be heavily dominated by either water or land. Convergence towards the Earth's equitably partitioned surface may occur if a strong feedback mechanism acts to regulate the exposure of land. It is therefore feasible that the Earth's relatively balanced division of land and sea is highly atypical amongst habitable planets. We construct a simple model for the anthropic selection bias that may arise from an ensemble of surface conditions. Across a broad class of models we consistently find that (a) the Earth's ocean coverage of 71% can be readily accounted for by observational selection effects, and (b) due to our proximity to the waterworld limit, the maximum likelihood model is one where the majority of habitable planets are waterworlds. This 'Dry Earth' scenario is consistent with results from numerical simulations, and could help explain the apparently low-mass transition in the mass-radius relation. (Abstract)

On a purely statistical basis, one naıvely expects to find a highly asymmetric division of land and ocean surface areas. A natural explanation for the Earth’s equitably partitioned surface is an anthropic selection process. We have highlighted two mechanisms which could be responsible for driving this selection effect. First of all, planets with highly asymmetric surfaces (desert worlds or waterworlds) are likely to produce intelligent species at a much lower frequency. Secondly, planets with larger habitable areas are capable of sustaining larger populations. Both of these factors imply that our host planet has a greater habitable area than most life-bearing worlds. (7) It has been argued that the apparently unique and special properties of the Earth is indicative of the sparsity of life in the Universe - the so-called ‘Rare Earth hypothesis’. However this interpretation fails to account for one of the factors which controls the fecundity: the number of observers produced by each planet. This amplifies the already considerable observational selection effects associated with the emergence of life. The parameters of an observer’s host planet are heavily skewed in favour of those conditions which maximize the abundance of life, not just the probability of its emergence. The apparent fine-tuning of the Earth’s parameters need not reflect the sparsity of life in the cosmos, but on the contrary, it may be driven precisely because we are a small piece within a vast ensemble. (8)

[Prev Pages]   Previous   | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19  Next