780 results on '"ORIGIN of the solar system"'
Search Results
2. The origin of life in fire and ice
- Published
- 2022
3. SOLAR SYSTEM SMASHUP.
- Author
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Elkins-Tanton, Linda T.
- Subjects
- *
PLANETESIMALS , *METEORS , *MAGNETIC fields , *ALUMINUM isotopes , *ORIGIN of planets ,ORIGIN of the solar system - Abstract
The article focuses on alternative views on the formation of the solar system as a result of analysis of meteors which suggest a more chaotic formation than older solar system models suggested. It commented on the discovery of meteors that are partially differentiated and harbored signs of an ancient magnetic field in the rock. It talks about the possible role of unstable aluminum isotopes called 26Al which could have heated planetesimals and eventually formed planets.
- Published
- 2016
- Full Text
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4. Worlds More or Less: Nineteenth-Century Ethno-Astronomy and Cosmologies of Reference.
- Author
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Garofalo, Devin M.
- Subjects
- *
NEBULAR hypothesis , *ETHNOASTRONOMY ,ORIGIN of the solar system - Abstract
This essay reads William Herschel's nebular hypothesis (and the debates it galvanized) in light of Sylvia Wynter's account of the cosmology of Man. Tracing the relationship between Western monohumanism and "ethno-astronomy," Wynter demonstrates how the post-Copernican worldview posited Earth as materially contiguous with the heavens and only one sphere among many. If, as Wynter argues, this rupture facilitated the transhistorical absolutization of Man as the human, the question of form is key to this history. For, insofar as the form of the sphere differentiates world-making Man from merely world-inhabiting Others (both human and nonhuman), it subtends British colonial schemas of empire and race. Nineteenth-century writings about nebulae are curious in this context for how they figure beyond the ethno-astronomy of Man. In attempting to formalize nebulae—gossamer celestial objects that possess no outline—thinkers from Thomas De Quincey to John Pringle Nichol glimpse a cosmos that discomposes the contiguities of both matter and reference upon which the colonial liberal subject's cosmology of whiteness depends. This becomes especially apparent as nebulae turn the workings of analogy haywire. Pushed to the point of failure, analogy inadvertently discerns and asserts a world whose pluriversal configurations of human and nonhuman might inform anti- and decolonial projects. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
5. Universal : A Guide to the Cosmos
- Author
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Brian Cox, Jeff Forshaw, Brian Cox, and Jeff Forshaw
- Subjects
- Popular works, Cosmology--Popular works, Big bang theory--Popular works, Cosmology, SCIENCE / Cosmology, SCIENCE / Physics, Big bang theory, Origin of the Solar system
- Abstract
An awe-inspiring, unforgettable journey of scientific exploration from Brian Cox and Jeff Forshaw, the international bestselling authors of Why Does E=MC2? and The Quantum Universe, with 55 black-&-white and 45 full-color pages featuring photographs, diagrams, maps, tables, and graphs. We dare to imagine a time before the Big Bang, when the entire universe was compressed into a space smaller than an atom. And now, as Brian Cox and Jeff Forshaw show, we can do more than imagine: we can understand.Universal takes us on an epic journey of scientific exploration. It reveals how we can all come to grips with some of the most fundamental questions about our Earth, Sun, and solar system--and the star-filled galaxies beyond. How big is our solar system? How quickly is space expanding? How big is the universe? What is it made of? Some of these questions can be answered on the basis of observations you can make in your own backyard. Other answers draw on the astonishing information now being gathered by teams of astronomers operating at the frontiers of the known universe.At the heart of all this lies the scientific method. Science reveals a deeper beauty and connects us to each other, to our world, and to our universe. Science reaches out into the unknown. As Universal demonstrates, if we dare to imagine, we can do the same.
- Published
- 2017
6. NOT FROM AROUND HERE.
- Author
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Zwart, Simon Portegies
- Subjects
- *
KUIPER belt , *OORT Cloud , *SEDNA (Dwarf planet) , *HALE-Bopp comet ,ORIGIN of the solar system - Abstract
The article explores alien interloper between the Kuiper belt and Oort cloud. Topics discussed include the formation of the solar system, the possible origin of the Sedna planet and other bodies outside the solar system and not from the Oort cloud, and the appearance of the Hale-Bopp comet which suggests the vastness of the solar system.
- Published
- 2016
- Full Text
- View/download PDF
7. BORN OF CHAOS.
- Author
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Batygin, Konstantin, Laughlin, Gregory, and Morbidelli, Alessandro
- Subjects
- *
SOLAR system , *ORBITAL mechanics , *JUPITER (Planet) , *ORIGIN of planets , *CONJUNCTIONS (Astronomy) ,EVOLUTION ,ORIGIN of the solar system - Abstract
The article discusses the birth and early history of the solar system. Emphasis is given to the violent and dynamic aspects of phenomena such as orbital migrations of planets, the mutability of protoplanet disks, and the collisional grinding and aerodynamic drag caused by movement of the planet Jupiter. Other topics include the inner grouping and alignment of rocky planets versus the outer grouping of gas giant planets such as Saturn.
- Published
- 2016
- Full Text
- View/download PDF
8. Pluto and beyond.
- Author
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Lemonick, Michael D.
- Subjects
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TRANS-Neptunian objects , *PLUTO (Dwarf planet) , *CHURYUMOV-Gerasimenko comet , *KUIPER belt , *OORT Cloud ,ORIGIN of the solar system - Abstract
The article discusses space probes that are getting close-up looks at comets, asteroids, and dwarf planets from the Kuiper belt, revealing how the origin of the solar system. Topics include the study of comet 67P/Churyumov-Gerasimenko by the European Space Agency's (ESA's) Rosetta space probe, the study of the dwarf planet Pluto by the U.S. National Aeronautics and Space Administration's (NASA's) New Horizons probe, and a historical overview of the Kuiper belt and the Oort cloud.
- Published
- 2014
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9. Moon, Origin of
- Author
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Melosh, H. Jay, Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Cleaves, Henderson James (Jim), II, editor, Pinti, Daniele L., editor, Quintanilla, José Cernicharo, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor
- Published
- 2015
- Full Text
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10. Formation of the Solar System : A New Theory of the Creation and Decay of the Celestial Bodies
- Author
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V.I. Ferronsky, S.V. Ferronsky, V.I. Ferronsky, and S.V. Ferronsky
- Subjects
- Origin of the Solar system
- Abstract
Analysis of the orbital motion of the Earth, the Moon and other planets and their satellites led to the discovery that all bodies in the Solar System are moving with the first cosmic velocity of their proto parents. The mean orbital velocity of each planet is equal to the first cosmic velocity of the Protosun, the radius of which is equal to the semi-major axis of the planet's orbit. The same applies for the planets'satellites. All the small planets, comets, other bodies and the Sun itself follow this law, a finding that has also been proven by astronomical observations. The theoretical solutions based on the Jacobi dynamics explain the process of the system creation and decay, as well as the nature of Kepler's laws.
- Published
- 2013
11. Secrets of primitive meteorites.
- Author
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Rubin, Alan E.
- Subjects
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CHONDRITES , *CLASSIFICATION of meteorites , *METEORITE analysis , *CHONDRULES , *COSMIC dust , *PROTOPLANETARY disks , *T Tauri stars , *SOLAR system ,ORIGIN of the solar system - Abstract
The article discusses research into the composition and properties of chondrite meteorite fragments in order to determine their cosmic origins. Particular focus is given to the analysis of chondrule silicate minerals, which formed into asteroids with dust and other metals, and the estimation of the original locations of several types of chondrites through the distribution of cosmic dusts at their formation. The results suggest a structure for the early solar system similar to that of the protoplanetary discs surrounding young T Tauri stars.
- Published
- 2013
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12. Origin of the universe.
- Author
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Turner, Michael S.
- Subjects
- *
HISTORY of cosmology , *ASTROPHYSICS , *QUARKS , *DARK energy , *EXPANDING universe ,ORIGIN of the solar system - Abstract
The article discusses the origin of the universe. The focus of the article is the universe's evolution from a quark soup to a complex system of galaxies, stars, planets, and life. Topics include an in-depth discussion on how the emergence of these features were guided by the basic laws of physics and the role of dark energy, which is an unknown form of energy that caused the expansion of the cosmos billions of years ago. INSET: In the Dark.
- Published
- 2009
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13. The dark ages of the universe.
- Author
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Loeb, Abraham
- Subjects
- *
COSMOCHRONOLOGY , *ORIGIN of planets , *ASTRONOMICAL observations , *QUANTITATIVE research , *BIG bang theory , *CHARTS, diagrams, etc. , *SCIENTIFIC discoveries ,ORIGIN of the solar system - Abstract
The article offers a look at how astronomers and cosmologists are addressing fundamental questions about the formation of the universe based on systematic observation and a quantitative methodology. According to the author, the goal of observational cosmology is to capture the entire history of the universe. Included is a diagram that shows the timeline of the development of the universe, including the Big Bang and the Dark Ages. INSETS: Overview;HOW TO SEE IN THE DARK.
- Published
- 2006
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14. A universe of disks.
- Author
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Blaes, Omer
- Subjects
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DISKS (Astrophysics) , *STARS , *GALAXY formation , *ELLIPTICAL galaxies , *SPIRAL galaxies , *ANGULAR momentum (Mechanics) , *ASTROPHYSICS , *ACCRETION (Astrophysics) , *SUPERMASSIVE black holes ,ORIGIN of the solar system - Abstract
The article looks at research on accretion disks around new stars. In some binary star systems, gas escapes from one star and is captured by the gravity of the other to form a disk. Inside the disk, the gas slowly works its way down to the stellar surface in a tight, spiraling motion. Such structures, called accretion disks, are also thought to exist around supermassive black holes at the centers of galaxies. Astronomers believe that accretion disks around supermassive black holes may have influenced the way galaxies formed and evolved. The conservation of angular momentum explains why disks are so prevalent in the universe. Spiral galaxies emerge from gas that becomes rotationally supported before patches of the gas contract into stars. If stars are born in the gas before the galactic cloud becomes rotationally supported, the stars will maintain their individual orbits around the galactic center, creating an elliptical galaxy. Although much of the gravitational binding energy released by the spiraling material in accretion disks ends up in the form of radiation, sometimes the energy also drives winds and jets of particles from the disk. Some systems, such as young stars and certain classes of active galactic nuclei, produce very fast, narrow jets of particles extending up to several light-years in the case of young stars and to more than several million light-years for active galactic nuclei. INSETS: BIRTH OF A DISK;A Gallery of Disks and Jets;HOW A DISK SPIRALS AND RADIATES;A DISK INSTABILITY
- Published
- 2004
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15. Star dust.
- Author
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Holmes, Hannah
- Subjects
- *
COSMIC dust ,ORIGIN of the solar system - Abstract
Discusses studies suggesting that space dust may hold the clues to which stars parented the solar system. Sources of space dust; Efforts to find the exact number of stars that contributed dust to the solar system's birth cloud; Endurance of stardusts such as silicon carbide, graphite, sapphire and diamond.
- Published
- 2001
16. Origin of planetary systems.
- Author
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Adler, Robert
- Subjects
- *
STARS , *PLANETS , *ASTRONOMY ,ORIGIN of the solar system - Abstract
Discusses the formation of solar systems, and observations by scientists. Creation of stars and planets; Growth of planets from planetesimals to protoplanets; Comparisons of planets found in solar systems to the Earth; Opposition to theories concerning the creation of solar systems. INSETS: Celestial sleuthing;Visions of the future.
- Published
- 2000
17. Maps of planet-forming zones will help the hunt for alien life.
- Author
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Crane, Leah
- Subjects
- *
PROTOPLANETARY disks , *STAR observations ,ORIGIN of the solar system - Abstract
The article discusses research which found that each of the protoplanetary discs around five nearby stars has a unique chemical make-up that varies significantly between different areas within each disc.
- Published
- 2021
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18. Distinct chlorine isotopic reservoirs on Mars. Implications for character, extent and relative timing of crustal interactions with mantle-derived magmas, evolution of the martian atmosphere, and the building blocks of an early Mars.
- Author
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Shearer, C.K., Messenger, S., Sharp, Z.D., Burger, P.V., Nguyen, A.N., and McCubbin, F.M.
- Subjects
- *
NEBULAR hypothesis , *CHLORINE , *LITHOSPHERE , *TRACE elements ,ORIGIN of the solar system - Abstract
The δ 37 Cl from different generations of apatite in martian meteorite Chassigny has a range of ≈10‰ and is almost as great as measurements made on all martian meteorites (≈14‰). This range represents the mixing of distinct Cl isotope reservoirs during the formation of Chassigny: (1) an isotopically light-Cl mantle reservoir (δ 37 Cl = −4 to −6‰) that exhibits limited variability and (2) an isotopically heavy Cl crustal reservoir (δ 37 Cl > 0) that exhibits significant variability. The mantle component documented in Chassigny melt inclusions that host a solar noble gas composition are derived from pristine, martian mantle. The incompatible element depleted and enriched shergottite sources as defined by radiogenic isotope systematics and trace element concentration ratios have very similar Cl isotopic signatures and suggest that both are derived from the martian mantle. The enrichment of isotopically heavy Cl in the crust resulted from protracted loss of 35 Cl to space that started early in the history of Mars. The Cl isotopic signature of the martian mantle is different from the Earth, Moon, and many primitive meteorites (δ 37 Cl = 0), suggesting that these differences represent distinct Cl sources in the solar nebula. The low δ 37 Cl source represents the primordial Solar System composition from which Mars accreted. The higher δ 37 Cl values observed for the Earth, Moon, and many chondrites are not primordial, rather they represent the later incorporation of 37 Cl-enriched HCl-hydrates into accreting material. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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19. Debris disc constraints on planetesimal formation.
- Author
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Krivov, Alexander V., Ide, Aljoscha, Löhne, Torsten, Johansen, Anders, and Blum, Jürgen
- Subjects
- *
PLANETESIMALS , *PROTOPLANETARY disks , *ACCRETION (Astrophysics) , *ASTROPHYSICAL collisions ,ORIGIN of the solar system - Abstract
Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical 'slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentrationmodels -- provided the objects are loosely bound 'pebble piles' as thesemodels also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a 'disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ~1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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20. Frozen in time.
- Author
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Davies, John
- Subjects
ORIGIN of the solar system - Abstract
Focuses on the origin of the solar system. Theories on its origin; Composition of the terrestrial planets and the main asteroid belt between Mars and Jupiter; Entry of comets on the solar system; Study made on Kuiper disc; Discovery of the Minor Planet 2060 in an eccentric orbit between Uranus and Saturn.
- Published
- 1996
21. Survivors from Mars.
- Author
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Davies, Paul
- Subjects
- *
ORIGIN of the Earth , *ORIGIN of planets , *MARS (Planet) , *METEORITES ,ORIGIN of the solar system - Abstract
Discusses a theory that Earth was seeded with Martian microorganisms. Formation of the Solar System; Collisions between partly formed planets; Speculation as to how life on the early Earth could have endured repeated impacts from space debris; Study of hyperthermophiles; Theories on underground colonies of organisms. INSET: Superbug survival.
- Published
- 1998
22. SCIENCE AND THE CITIZEN.
- Subjects
SCIENCE ,COAL ,NUCLEAR power plants ,CHROMOSOMES ,SUPERNOVAE ,ORIGIN of the solar system - Abstract
The article offers news briefs related to science in the U.S. The estimated amount of coal represents 90 percent of the total fossil fuel reserves. Nuclear power plants make up 9 percent of the country's total electric-generating capacity. A study revealed that the individuality of tissue from different human beings is asserted by the protein products of genes at four loci on the short arm of chromosome number 6. Evidences have been gathered that suggests that supernovas in the galaxy must have preceded the creation of the solar system.
- Published
- 1978
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23. The Origin and Evolution of the Solar System.
- Author
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Cameron, A. G. W.
- Subjects
ORIGIN of the solar system ,METAPHYSICAL cosmology - Abstract
The article explores several theories about the origin and evolution of the solar system. Scientist Rene Descartes has proposed that the sun and the planets were formed out of a rotating disk of gas and dust. In Georges Louis Leclerc de Buffon's theory, he proposed that a massive comet came close to the sun and ripped out of it the material that constituted the planets and their satellites. According to the author, the most significant theory were the ones made by Immanuel Kant and Pierre Simon de Laplace who elaborated Descartes's original idea.
- Published
- 1975
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24. The Most Primitive Objects in the Solar System.
- Author
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Grossman, Lawrence
- Subjects
CHONDRITES ,METEORITES ,ORIGIN of the solar system ,NEBULAR hypothesis ,METAPHYSICAL cosmology - Abstract
The article focuses on primitive meteorites which are commonly known as chondrites. Meteorites are used as a medium to gain vital scientific information about the origins of the solar system. It is believed that the solar system evolved out of a nebula of dust and gases about 4.6 billion years ago. Scientific analysis shows that some of the unaltered primitive mixture of minerals condensed in the form of these chondrites over a wide range of temperatures before the formation of the solar system.
- Published
- 1975
- Full Text
- View/download PDF
25. Life outside the Solar System.
- Author
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Su-Shu Huang
- Subjects
STARS ,GALAXIES ,ORGANISMS ,PLANETS ,ORIGIN of the solar system ,EVOLUTIONARY theories - Abstract
The article focuses on the relationship between the appearance of the formation of the stars and the evolution of living organisms. A hypothesis states that a star is formed by the condensation of a cloud of dust and gas, which explains the origin of the solar system. According to astronomers, a life-bearing planet would have to travel on an orbit close to one of the stars in a separated system or on an orbit at a large distance from the stars in a close system.
- Published
- 1960
- Full Text
- View/download PDF
26. Major achievements of the Rosetta mission in connection with the origin of the solar system.
- Author
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Barucci, M. and Fulchignoni, M.
- Subjects
- *
SPACE flight , *PLANETARY gravitation , *CHURYUMOV-Gerasimenko comet ,ORIGIN of the solar system - Abstract
Comets have been studied from a long time and are believed to preserve pristine materials, so they are fundamental to understand the origin of the solar system and life. Starting in the early 1990s, ESA decided to have a more risky and fantastic mission to a comet. As Planetary Cornerstone mission of the ESA Horizon 2000 program, the Rosetta mission was selected with the aim of realizing two asteroid fly-bys, a rendezvous with a comet to deliver a surface science package and to hover around the comet from 4 AU inbound up to perihelion and outbound back to 3.7 AU. The mission was successfully launched on March 2, 2004 with Ariane V that started its 10-year journey toward comet 67P/Churyumov-Gerasimenko. After several planetary gravity assists, Rosetta flew by two asteroids-on September 5, 2008 (Steins) and on July 10, 2010 (Lutetia), respectively, and performed the comet orbit insertion maneuver on August 6, 2014. The onboard instruments characterized the nucleus orbiting the comet at altitudes down to few kilometers. On November 12, 2014, the lander Philae was delivered realizing the first landing ever on a comet surface. Although the exploration of the comet was planned up to the end of 2015, the mission duration was extended for nine more months than the nominal one, to follow the comet on its outbound orbit. To terminate the mission, following a series of very low orbits, a controlled impact of Rosetta spacecraft with the comet was realized on September 30, 2016. The scientific objectives of the mission have been largely achieved. The challenging mission provided the science community with an enormous quantity of data of extraordinary scientific value. In this paper, a detailed description of the mission and the highlights of the obtained scientific results on the exploration of an extraordinary world are presented. The paper also includes lessons learned and directions for the future. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
27. The Late Heavy Bombardment.
- Author
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Bottke, William F. and Norman, Marc D.
- Subjects
- *
ASTEROID belt , *CRATERING , *MARS (Planet) , *LUNAR exploration ,ORIGIN of the solar system - Abstract
Heavily cratered surfaces on the Moon, Mars, and Mercury show that the terrestrial planets were battered by an intense bombardment during their first billion years or more, but the timing, sources, and dynamical implications of these impacts are controversial. The Late Heavy Bombardment refers to impact events that occurred after stabilization of the planetary lithospheres such that they could be preserved as craters and basins. Lunar melt rocks and meteorite shock ages point toward a discrete episode of elevated impact flux between ∼3.5 and ∼4.0-4.2 Ga, and a relative quiescence between ∼4.0-4.2 and ∼4.4 Ga. Evidence from Precambrian impact spherule layers suggests that a long-lived tail of terrestrial impactors lasted to ∼2.0-2.5 Ga. Dynamical models that include populations residual from primary accretion and destabilized by giant planet migration can potentially account for the available observations, although all have pros and cons. The most parsimonious solution to match constraints is a hybrid model with discrete early, post-accretion and later, planetary instability-driven populations of impactors. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
28. Early formation of planetary building blocks inferred from Pb isotopic ages of chondrules.
- Author
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Bollard, Jean, Connelly, James N., Whitehouse, Martin J., Pringle, Emily A., Bonal, Lydie, Jørgensen, Jes K., Nordlund, Åke, Moynier, Frédéric, and Bizzarro, Martin
- Subjects
- *
CHONDRULES , *CHONDRITES , *PROTOPLANETARY disks , *PLANETESIMALS ,ORIGIN of the solar system - Abstract
The article reports that primary production of chondrules, formed by transient melting events in the solar protoplanetary disk, was restricted to the first million years after the formation of the Sun. These millimeter-sized glassy spherical chondrules were recycled for the remaining lifetime of the protoplanetary disk.
- Published
- 2017
- Full Text
- View/download PDF
29. Planetesimal formation by an axisymmetric radial bump of the column density of the gas in a protoplanetary disk.
- Author
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Onishi, Isamu and Sekiya, Minoru
- Subjects
- *
PROTOPLANETARY disks , *PLANETESIMALS , *PROPERTIES of matter , *ACCRETION (Astrophysics) ,ORIGIN of the solar system - Abstract
We investigate the effect of a radial pressure bump in a protoplanetary disk on planetesimal formation. We performed the two-dimensional numerical simulation of the dynamical interaction of solid particles and gas with an initially defined pressure bump under the assumption of axisymmetry. The aim of this work is to elucidate the effects of the stellar vertical gravity that were omitted in a previous study. Our results are very different from the previous study, which omitted the vertical gravity. Because dust particles settle toward the midplane because of the vertical gravity to form a thin dust layer, the regions outside of the dust layer are scarcely affected by the back-reaction of the dust. Hence, the gas column density keeps its initial profile with a bump, and dust particles migrate toward the bump. In addition, the turbulence due to the Kelvin-Helmholtz instability caused by the difference of the azimuthal velocities between the inside and outside of the dust layer is suppressed where the radial pressure gradient is reduced by the pressure bump. The dust settling proceeds further where the turbulence is weak, and a number of dust clumps are formed. The dust density in some clumps exceeds the Roche density. Planetesimals are considered to be formed from these clumps owing to the self-gravity. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
30. SPH simulations of structures in protoplanetary disks.
- Author
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Demidova, T. and Grinin, V.
- Subjects
- *
PROTOPLANETARY disks , *CIRCUMSTELLAR matter , *HYDRODYNAMICS , *AZIMUTHAL projection (Cartography) ,ORIGIN of the solar system - Abstract
Using the GADGET-2 code modified by us, we have computed hydrodynamic models of a protoplanetary disk perturbed by a low-mass companion. We have considered the cases of circular and eccentric orbits coplanar with the disk and inclined relative to its midplane. During our simulations we computed the column density of test particles on the line of sight between the central star and observer. On this basis we computed the column density of circumstellar dust by assuming the dust and gas to be well mixed with a mass ratio of 1: 100. To study the influence of the disk orientation relative to the observer on the interstellar extinction, we performed our computations for four inclinations of the line of sight to the disk plane and eight azimuthal directions. The column densities in the circumstellar disk of the central star and the circumbinary disk were computed separately. Our computations have shown that periodic column density oscillations can arise in both inner and circumbinary disks. The amplitude and shape of these oscillations depend on the system's parameters (the orbital eccentricity and inclination, the component mass ratio) and its orientation in space. The results of our simulations can be used to explain the cyclic brightness variations of young UX Ori stars. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
31. A test field for Gaia.
- Author
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Frémat, Y., Altmann, M., Pancino, E., Soubiran, C., Jofré, P., Damerdji, Y., Heiter, U., Royer, F., Seabroke, G., Sordo, R., Blanco-Cuaresma, S., Jasniewicz, G., Martayan, C., Thévenin, F., Vallenari, A., Blomme, R., David, M., Gosset, E., Katz, D., and Viala, Y.
- Subjects
- *
GAIA hypothesis , *RADIAL velocity of stars , *ECLIPTIC , *SPHERICAL astronomy ,ORIGIN of the solar system - Abstract
Context. Gaia is a space mission that is currently measuring the five astrometric parameters, as well as spectrophotometry of at least 1 billion stars to G = 20:7 mag with unprecedented precision. The sixth parameter in phase space (i.e., radial velocity) is also measured thanks to medium-resolution spectroscopy that is being obtained for the 150 million brightest stars. During the commissioning phase, two fields, one around each ecliptic pole, have been repeatedly observed to assess and to improve the overall satellite performances, as well as the associated reduction and analysis software. A ground-based photometric and spectroscopic survey was therefore initiated in 2007, and is still running to gather as much information as possible about the stars in these fields. This work is of particular interest to the validation of the radial velocity spectrometer outputs. Aims. The paper presents the radial velocity measurements performed for the Southern targets in the 12-17 R magnitude range on high- to mid-resolution spectra obtained with the GIRAFFE and UVES spectrographs. Methods. Comparison of the South Ecliptic Pole (SEP) GIRAFFE data to spectroscopic templates observed with the HERMES (Mercator in La Palma, Spain) spectrograph enabled a first coarse characterisation of the 747 SEP targets. Radial velocities were then obtained by comparing the results of three different methods. Results. In this paper, we present an initial overview of the targets to be found in the 1 sq. deg SEP region that was observed repeatedly by Gaia ever since its commissioning. In our representative sample, we identified one galaxy, six LMC S-stars, nine candidate chromospherically active stars, and confirmed the status of 18 LMC Carbon stars. A careful study of the 3471 epoch radial velocity measurements led us to identify 145 RV constant stars with radial velocities varying by less than 1 km s-1. Seventy-eight stars show significant RV scatter, while nine stars show a composite spectrum. As expected, the distribution of the RVs exhibits two main peaks that correspond to Galactic and LMC stars. By combining [Fe=H] and log g estimates, and RV determinations, we identified 203 members of the LMC, while 51 more stars are candidate members. Conclusions. This is the first systematic spectroscopic characterisation of faint stars located in the SEP field. During the coming years, we plan to continue our survey and gather additional high- and mid-resolution data to better constrain our knowledge on key reference targets for Gaia. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
32. Cavity and other radial substructures in the disk around HD 97048.
- Author
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van der Plas, G., Wright, C. M., Ménard, F., Casassus, S., Canovas, H., Pinte, C., Maddison, S. T., Maaskant, K., Avenhaus, H., Cieza, L., Perez, S., and Ubach, C.
- Subjects
- *
CAVITY resonators , *PROTOPLANETARY disks , *T Tauri stars , *HERBIG Ae/Be stars ,ORIGIN of the solar system - Abstract
Context. Gaps, cavities, and rings in circumstellar disks are signposts of disk evolution and planet-disk interactions. We follow the recent suggestion that Herbig Ae/Be disks with a flared disk harbor a cavity, and investigate the disk around HD 97048. Aims. We aim to resolve the 34 ± 4 AU central cavity that has been predicted and to investigate the structure of the disk. Methods. We imaged the disk around HD 97048 using ALMA at 0.85 mm and 2.94 mm and ATCA (multiple frequency) observations. Our observations also include the 12CO J = 1-0, 12CO J = 3-2 and HCO+ J = 4-3 emission lines. Results. A central cavity in the disk around HD 97048 is resolved with a 40-46 AU radius. Additional radial structure present in the surface brightness profile can be accounted for either by an opacity gap at 90 AU or by an additional emitting ring at 150 AU. The continuum emission tracing the dust in the disk is detected out to 355 AU. The 12CO J = 3-2 disk is detected 2.4 times farther out. The 12CO emission can be traced down to ≈10 AU scales. Apparent non-Keplerian kinematics are detected inside the cavity on the HCO+ J = 4-3 velocity map. The mm spectral index measured from ATCA observations suggests that grain growth has occurred in the HD 97048 disk. Finally, we resolve a highly inclined disk out to 150 AU around the nearby 0.5 M⊙ binary ISO-ChaI 126. Conclusions. The data presented here reveal a cavity in the disk of HD 97048, and prominent radial structure in the surface brightness. The cavity size varies for different continuum frequencies and gas tracers. The gas inside the cavity follows non-Keplerian kinematics seen in HCO+ emission. The variable cavity size along with the kinematical signature suggests the presence of a substellar companion or a massive planet inside the cavity. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
33. Asteroids 87887 - 415992: the youngest known asteroid pair?
- Author
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Žižka, J., Galád, A., Vokrouhlický, D., Pravec, P., Kušnirák, P., and Hornoch, K.
- Subjects
- *
ASTEROIDS , *CELESTIAL mechanics , *ASTEROID orbits , *ASTRONOMICAL photometry ,ORIGIN of the solar system - Abstract
Context. Pairs of asteroids, that is, couples of single bodies on tightly similar heliocentric orbits, were recently postulated as a new category of objects in the solar system. They are believed to be close twins to binary and multiple systems. Aims. Ages of the known pairs range from about 15 kyr to nearly a million years. Beyond the upper limit, the pairs disperse in the background population of asteroids and become difficult to detect. Below the lower limit, the pairs should be easily recognizable if they exist and are discovered by surveys. Using the available data, we analyze the possible existence of very young asteroid pairs with clearly proven ages ≤10 kyr. Methods. We searched for candidate very young asteroid pairs in the current catalog of asteroid orbits. After a preliminary analysis, we selected the most promising case of the small asteroids (87887) 2000 SS286 and (415992) 2002 AT49. We collected photometric observations to determine their rotation periods and absolute magnitudes. Results. The rotation period of (87887) 2000 SS286 is 5:7773 ± 0:0004 h. Analysis of the data for (415992) 2002 AT49 indicates as the most probable period 2:6366 ± 0:0003 h, but other solutions are still possible. The composite light curves of the two asteroids have very low amplitudes, 0:22 and 0:12 mag, suggesting roundish shapes. Our observations also allow us to determine the absolute magnitude in R band HR = 14:99 ± 0:04 and HR = 16:24 ± 0:03 for the primary and secondary components. A transformation to the visible band provides H = 15:44 ± 0:05 and H = 16:69 ± 0:04. These two asteroids experienced a very close encounter, probably a formation event, some 7:4 ± 0:3 kyr ago. The formal extension of our numerical runs backward in time reveal that these close encounters may have continued, starting from ≃45 kyr ago. However, based on tests using synthetic fission events, we argue that the older age solutions might be the true solution only at ≃(10-15)% level, assuming their low initial separation velocity is of between 10-20 cm s-1. This means that 87887-415992 probably is the youngest known asteroid pair in our dataset with a reliable determined age. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
34. Our solar system’s 'shocking' origin story
- Published
- 2017
35. New insights into HOW THE SOLAR SYSTEM FORMED.
- Author
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Emspak, Jesse
- Subjects
- *
SOLAR system , *ORIGIN of planets ,ORIGIN of the solar system ,EVOLUTION - Abstract
The article offers information on the origin and formation of the solar system. The early solar system is known to be populated with tiny planetesimals, which led to the formation of planets around the Sun. NASA's Kepler spacecraft has found thousands of exoplanet systems existing the universe. Scott Kenyon, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, wrote that planets form in a few hundred thousand years.
- Published
- 2018
36. Diffuse gas in retired galaxies: nebular emission templates and constraints on the sources of ionization.
- Author
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Johansson, Jonas, Woods, Tyrone E., Gilfanov, Marat, Sarzi, Marc, Yan-Mei Chen, and Oh, Kyuseok
- Subjects
- *
TIDAL stripping (Astrophysics) , *NEBULAR hypothesis , *ACTIVE galactic nuclei ,ORIGIN of the solar system - Abstract
We present emission-line templates for passively-evolving ('retired') galaxies, useful for investigation of the evolution of the interstellar medium in these galaxies, and characterization of their high-temperature source populations. The templates are based on high signal-tonoise (>800) co-added spectra (3700-6800Å) of ~11 500 gas-rich Sloan Digital Sky Survey galaxies devoid of star formation and active galactic nuclei. Stacked spectra are provided for the entire sample and sub-samples binned by mean stellar age. In our previous paper, Johansson et al., these spectra provided the first measurements of the He II 4686Å line in passively-evolving galaxies, and the observed He II/Hβ ratio constrained the contribution of accreting white dwarfs (the 'single-degenerate' scenario) to the Type Ia supernova rate. In this paper, the full range of unambiguously detected emission lines are presented. Comparison of the observed [O I] 6300Å/Hα ratio with photoionization models further constrains any high-temperature single-degenerate scenario for Type Ia supernovae (with 1.5 ≲ T/105 K ≲ 10) to ≲3-6 per cent of the observed rate in the youngest age bin (i.e. highest SN Ia rate). Hence, for the same temperatures, in the presence of an ambient population of post-asymptotic giant branch stars, we exclude additional high-temperature sources with a combined ionizing luminosity of ≈1.35 × 1030 L☉/M☉,* for stellar populations with mean ages of 1-4 Gyr. Furthermore, we investigate the extinction affecting both the stellar and nebular continuum. The latter shows about five times higher values. This contradicts isotropically distributed dust and gas that renders similar extinction values for both cases. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
37. The Astrobiology Primer v2.0.
- Author
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Domagal-Goldman, Shawn D., Wright, Katherine E., Adamala, Katarzyna, Arina de la Rubia, Leigh, Bond, Jade, Dartnell, Lewis R., Goldman, Aaron D., Lynch, Kennda, Naud, Marie-Eve, Paulino-Lima, Ivan G., Singer, Kelsi, Walter-Antonio, Marina, Abrevaya, Ximena C., Anderson, Rika, Arney, Giada, Atri, Dimitra, Azúa-Bustos, Armando, Bowman, Jeff S., Brazelton, William J., and Brennecka, Gregory A.
- Subjects
- *
SPACE biology , *SOLAR system , *EVOLUTIONARY theories ,UNIVERSE ,EVOLUTION ,ORIGIN of the solar system - Abstract
The article presents a primer about astrobiology, which is a branch of science that studies the origin, evolution and the existence of life in the universe. Topics mentioned include the possibility of life discoveries elsewhere in the universe, understanding the definition of life as guide for scientific research and the common characteristics of life in planet earth.
- Published
- 2016
- Full Text
- View/download PDF
38. Portrait of the Polana–Eulalia family complex: Surface homogeneity revealed from near-infrared spectroscopy.
- Author
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Pinilla-Alonso, Noemí, de León, J., Walsh, K.J., Campins, H., Lorenzi, V., Delbo, M., DeMeo, F., Licandro, J., Landsman, Z., Lucas, M.P., Alí-Lagoa, V., and Burt, B.
- Subjects
- *
ASTEROID belt , *NEAR-earth asteroids , *NEAR infrared spectroscopy ,ORIGIN of the solar system - Abstract
The inner asteroid belt is an important source of near-Earth asteroids (NEAs). Dynamical studies of the inner asteroid belt have identified several families overlapping in proper orbital elements, including the Polana and Eulalia families that contain a large fraction of the low-albedo asteroids in this region. We present results from two coordinated observational campaigns to characterize this region through near-infrared (NIR) spectroscopy. These campaigns ran from August 2012 to May 2014 and used the NASA Infrared Telescope Facility and the Telescopio Nazionale Galileo. The observations focused on objects within these families or in the background, with low albedo ( p v ≤ 0.1) and low inclination ( i P ≤ 7°). We observed 63 asteroids (57 never before observed in the NIR): 61 low-albedo objects and two interlopers, both compatible with S- or E- taxonomical types. We found our sample to be spectrally homogeneous in the NIR. The sample shows a continuum of neutral to moderately-red concave-up spectra, very similar within the uncertainties. Only one object in the sample, asteroid (3429) Chuvaev , has a blue spectrum, with a slope ( S ′ = − 1.33 ± 0.21%/1000 Å) significantly different from the average spectrum ( S ′ = 0.68 ± 0.68%/1000 Å). This spectral homogeneity is independent of membership in families or the background population. Furthermore, we show that the Eulalia and Polana families cannot be distinguished using NIR data. We also searched for rotational variability on the surface of (495) Eulalia which we do not detect. (495) Eulalia shows a red concave-up spectrum with an average slope S ′ = 0.91 ± 0.60%/1000 Å, very similar to the average slope of our sample. The spectra of two targets of sample-return missions, (101955) Bennu, target of NASA’s OSIRIS-Rex and (162173) 1999 JU 3 target of the Japanese Space Agency’s Hayabusa-2, are very similar to our average spectrum, which would be compatible with an origin in this region of the inner belt. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
39. Gaps, rings, and non-axisymmetric structures in protoplanetary disks: Emission from large grains.
- Author
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Ruge, J. P., Flock, M., Wolf, S., Dzyurkevich, N., Fromang, S., Henning, Th., Klahr, H., and Meheut, H.
- Subjects
- *
PROTOPLANETARY disks , *ACCRETION (Astrophysics) , *SPATIAL distribution (Quantum optics) , *CIRCUMSTELLAR matter , *MAGNETOHYDRODYNAMICS ,ORIGIN of the solar system - Abstract
Aims. Dust grains with sizes around (sub)mm are expected to couple only weakly to the gas motion in regions beyond 10 au of circumstellar disks. In this work, we investigate the influence of the spatial distribution of these grains on the (sub)mm appearance of magnetized protoplanetary disks. Methods. We perform non-ideal global 3D magneto-hydrodynamic (MHD) stratified disk simulations, including particles of different sizes (50 μm to 1 cm), using a Lagrangian particle solver. Subsequently, we calculate the spatial dust temperature distribution, including the dynamically coupled submicron-sized dust grains, and derive ideal continuum re-emission maps of the disk through radiative transfer simulations. Finally, we investigate the feasibility of observing specific structures in the thermal re-emission maps with the Atacama Large Millimeter/submillimeter Array (ALMA). Results. Depending on the level of turbulence, the radial pressure gradient of the gas, and the grain size, particles settle to the midplane and/or drift radially inward. The pressure bump close to the outer edge of the dead-zone leads to particle-trapping in ring structures. More specifically, vortices in the disk concentrate the dust and create an inhomogeneous distribution of solid material in the azimuthal direction. The large-scale disk perturbations are preserved in the (sub)mm re-emission maps. The observable structures are very similar to those expected from planet-disk interaction. Additionally, the larger dust particles increase the brightness contrast between the gap and ring structures. We find that rings, gaps, and the dust accumulation in the vortex could be traced with ALMA down to a scale of a few astronomical units in circumstellar disks located in nearby star-forming regions. Finally, we present a brief comparison of these structures with those recently found with ALMA in the young circumstellar disks of HL Tau and Oph IRS 48. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
40. The Mars anomaly.
- Author
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Ornes, Stephen
- Subjects
- *
MARS (Planet) , *NEBULAR hypothesis , *PLANETS , *SPACE exploration ,ORIGIN of the solar system - Abstract
The article focuses on the conflicting ideas among researches modeling the solar system's formation when addressing the size of planet Mars. Topics discussed include the theory that the solar system began as an immense cloud of dust and gas called a nebula, the pebble accretion simulations, and a new simulation of the early solar system based on a wild ride, known as the Grand Tack theory.
- Published
- 2016
- Full Text
- View/download PDF
41. Generation of highly inclined protoplanetary discs through single stellar flybys.
- Author
-
Xiang-Gruess, M.
- Subjects
- *
PROTOPLANETARY disks , *ACCRETION (Astrophysics) , *HYDRODYNAMICS , *FLUID dynamics ,ORIGIN of the solar system - Abstract
We study the three-dimensional evolution of a viscous protoplanetary disc which is perturbed by a passing star on a parabolic orbit. The aim is to test whether a single stellar flyby is capable to excite significant disc inclinations which would favour the formation of so-called misaligned planets. We use smoothed particle hydrodynamics to study inclination, disc mass and angular momentum changes of the disc for passing stars with different masses. We explore different orbital configurations for the perturber's orbit to find the parameter spaces which allow significant disc inclination generation. Prograde inclined parabolic orbits aremost destructive leading to significant disc mass and angular momentum loss. In the remaining disc, the final disc inclination is only below 20°. This is due to the removal of disc particles which have experienced the strongest perturbing effects. Retrograde inclined parabolic orbits are less destructive and can generate disc inclinations up to 60°. The final disc orientation is determined by the precession of the disc angular momentum vector about the perturber's orbital angular momentum vector and by disc orbital inclination changes. We propose a sequence of stellar flybys for the generation of misalignment angles above 60°. The results taken together show that stellar flybys are promising and realistic for the explanation of misaligned Hot Jupiters with misalignment angles up to 60°. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
42. NGC 6778: strengthening the link between extreme abundance discrepancy factors and central star binarity in planetary nebulae.
- Author
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Jones, D., Wesson, R., García-Rojas, J., Corradi, R. L. M., and Boffin, H. M. J.
- Subjects
- *
PLANETARY nebulae , *INTERSTELLAR medium , *GALAXIES , *NEBULAR hypothesis ,ORIGIN of the solar system - Abstract
We present new optical spectra of the nearby, bright, planetary nebula NGC 6778. The nebula has been known to emit strong recombination lines for more than 40 years but this is the first detailed study of its abundances. Heavy element abundances derived from recombination lines are found to exceed those from collisionally excited lines by a factor of ~20 in an integrated spectrum of the nebula, which is among the largest known abundance discrepancy factors. Spatial analysis of the spectra shows that the abundance discrepancy factor is strongly, centrally peaked, reaching~40 close to the central star. The central star of NGC 6778 is known to be a short-period binary, further strengthening the link between high nebular abundance discrepancy factors and central star binarity. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
43. Distribution of mass of the protoplanetary disk HL Tau.
- Author
-
Buitrago Carreño, Nidia Yiseth, Poveda Tejada, Nicanor, and Vera-Villamizar, Nelson
- Subjects
- *
PROTOPLANETARY disks , *ORIGIN of planets ,ORIGIN of the solar system - Abstract
A recent image of ALMA, of the protoplanetary disk around the star HL Tau, shows that the disc consists of several bright concentric rings separated by gaps. There is a hypothesis that these gaps are due to the presence of planets, but there are some difficulties with this interpretation: The planets are too close, generating orbital instability and should not exist planetary formation processes so advanced because the star is too young. This paper shows that the gaps are an effect of the distribution of matter of the disk. In most models assume that the disc consists of a continuous distribution of materia and gas, however, by orbital resonance effect, the disc has an internal structure: It is a superposition of distribution functions that give rise to the characteristic shape of the disc. The mass distribution is obtained, and a preliminary study of the orbits is done, finding that they are stable. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
44. New Year's Day visit to a distant, tiny world.
- Author
-
Crane, Leah
- Subjects
- *
ROCKS , *NEW Year , *SPACE exploration , *SPACE photography ,ORIGIN of the solar system - Abstract
The article discusses how the U.S. National Aeronautics & Space Administration's New Horizons spacecraft was scheduled to fly past a space rock known as Ultima Thule on New Year's Day 2019 while traveling towards a tiny world called 2014 MU69, and it mentions how Ultima Thule is located 6.6 billion kilometres from Earth. The problems that are associated with photographing Ultima Thule are examined, along with research regarding the beginnings of the solar system.
- Published
- 2019
- Full Text
- View/download PDF
45. Evolution and dynamics of a solar active prominence.
- Author
-
Tetsuya MAGARA
- Subjects
- *
SOLAR system , *INTERPLANETARY medium , *SUN , *MAGNETOHYDRODYNAMICS ,EVOLUTION ,ORIGIN of the solar system - Abstract
The life of a solar active prominence, one of the most remarkable objects on the Sun, is full of dynamics; after first appearing on the Sun, the prominence continuously evolves with various internal motions and eventually produces a global eruption toward interplanetary space. Here we report that the whole life of an active prominence is successfully reproduced by performing as long-term amagnetohydrodynamic simulation of a magnetized prominence plasma as was ever done. The simulation reveals underlying dynamic processes that give rise to observed properties of an active prominence: invisible subsurface flows self-consistently produce the cancellation of magnetic flux observed in the photosphere, while observed but somewhat counterintuitive strong upflows are driven against gravity by enhanced gas pressure gradient force along a magnetic field line locally standing vertical. The most highlighted dynamic event, transition into an eruptive phase, occurs as a natural consequence of the self-consistent evolution of a prominence plasma interacting with a magnetic field, which is obtained by seamlessly reproducing dynamic processes involved in the formation and eruption of an active prominence. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
46. Hunting for Long-lived Protoplanetary Disks Observed with AKARI/FIS.
- Author
-
Qiong, LIU and Yao, LIU
- Subjects
- *
PROTOPLANETARY disks , *ACCRETION (Astrophysics) , *PARALLAX , *GEOMETRICAL optics ,ORIGIN of the solar system - Abstract
Twenty-one YSO (Young Stellar Object) candidates nearby the solar system have been identified through cross-correlating Hipparcos (High Precision Parallax Collecting Satellite) catalog with the AKARI/FIS YSO catalog, and the reliability is over 90%. The central objects cover the spectral types from B to M. The Hipparcos's accurate measurements of trigonometric parallaxes enable us to place these objects in the H-R diagram, which can be used to determine their ages by the isochrones of theoretical evolution trajectories. In this sample, two YSOs have been found to be older than 10 Myr. The spectral energy distributions (SEDs) from optical to infrared show that the two YSOs belong to the type II YSOs with protoplanetary disks. Furthermore, from the SED fitting, the ages of these two sources are constrained to be (14.1 ± 4.2) Myr and (16.8 ± 4.4) Myr, respectively. Therefore, two YSO candidates with long-lived protoplanetary disks have been detected in the AKARI/FIS data. The long-lived protoplanetary disks are closely related with the planet formation, and they are ideal birthplaces of protoplanets. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
47. Observations of Solids in Protoplanetary Disks.
- Author
-
ANDREWS, SEAN M.
- Subjects
- *
PROTOPLANETARY disks , *ASTRONOMICAL observations , *CIRCUMSTELLAR matter , *ORIGIN of planets ,ORIGIN of the solar system - Abstract
This review addresses the state of research that employs astronomical (remote sensing) observations of solids ("dust") in young circumstellar disks to learn about planet formation. The intention is for it to serve as an accessible, introductory, pedagogical resource for junior scientists interested in the subject. After some historical background and a basic observational primer, the focus is shifted to the three fundamental topics that broadly define the field: (1) demographics--the relationships between disk properties and the characteristics of their environments and hosts; (2) structure--the spatial distribution of disk material and its associated physical conditions and composition; and (3) evolution--the signposts of key changes in disk properties, including the growth and migration of solids and the impact of dynamical interactions with young planetary systems. Based on the state-of-the-art results in these areas, suggestions are made for potentially fruitful lines of work in the near future. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
48. Formation of terrestrial planets in disks evolving via disk winds and implications for the origin of the solar system's terrestrial planets.
- Author
-
Masahiro Ogihara, Hiroshi Kobayashi, Shu-ichiro Inutsuka, and Suzuki, Takeru K.
- Subjects
- *
INNER planets , *PROTOPLANETARY disks , *SOLAR wind ,SOLAR evolution ,ORIGIN of the solar system - Abstract
Context. Recent three-dimensional magnetohydrodynamical simulations have identified a disk wind by which gas materials are lost from the surface of a protoplanetary disk, which can significantly alter the evolution of the inner disk and the formation of terrestrial planets. A simultaneous description of the realistic evolution of the gaseous and solid components in a disk may provide a clue for solving the problem of the mass concentration of the terrestrial planets in the solar system. Aims. We simulate the formation of terrestrial planets from planetary embryos in a disk that evolves via magnetorotational instability and a disk wind. The aim is to examine the effects of a disk wind on the orbital evolution and final configuration of planetary systems. Methods. We perform N-body simulations of sixty 0.1 Earth-mass embryos in an evolving disk. The evolution of the gas surface density of the disk is tracked by solving a one-dimensional diffusion equation with a sink term that accounts for the disk wind. Results. We find that even in the case of a weak disk wind, the radial slope of the gas surface density of the inner disk becomes shallower, which slows or halts the Type I migration of embryos. If the effect of the disk wind is strong, the disk profile is significantly altered (e.g., positive surface density gradient, inside-out evacuation), leading to outward migration of embryos inside ∼1 AU. Conclusions. Disk winds play an essential role in terrestrial planet formation inside a few AU by changing the disk profile. In addition, embryos can undergo convergent migration to ∼1 AU in certainly probable conditions. In such a case, the characteristic features of the solar system's terrestrial planets (e.g., mass concentration around 1 AU, late giant impact) may be reproduced. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
49. SHAPEMOL: a 3D code for calculating CO line emission in planetary and protoplanetary nebulae.
- Author
-
Santander-García, M., Bujarrabal, V., Koning, N., and Steffen, W.
- Subjects
- *
NEBULAR hypothesis , *GALAXIES , *ACTIVE galaxies ,SOLAR evolution ,ORIGIN of the solar system - Abstract
Context. Modern instrumentation in radioastronomy constitutes a valuable tool for studying the Universe: ALMA has reached unprecedented sensitivities and spatial resolution, while Herschel/HIFI has opened a new window (most of the sub-mm and far-infrared ranges are only accessible from space) for probing molecular warm gas (~50-1000 K). On the other hand, the software SHAPE has emerged in the past few years as a standard tool for determining the morphology and velocity field of different kinds of gaseous emission nebulae via spatio-kinematical modelling. Standard SHAPE implements radiative transfer solving, but it is only available for atomic species and not for molecules. Aims. Being aware of the growing importance of the development of tools for simplifying the analyses of molecular data from new-era observatories, we introduce the computer code shapemol, a complement to SHAPE, with which we intend to fill the so-far under-developed molecular niche. Methods. shapemol enables user-friendly, spatio-kinematic modelling with accurate non-LTE calculations of excitation and radiative transfer in CO lines. Currently, it allows radiative transfer solving in the 12CO and 13CO J = 1-0 to J = 17-16 lines, but its implementation permits easily extending the code to different transitions and other molecular species, either by the code developers or by the user. Used along SHAPE, shapemol allows easily generating synthetic maps to test against interferometric observations, as well as synthetic line profiles to match single-dish observations. Results. We give a full description of how shapemol works, and we discuss its limitations and the sources of uncertainty to be expected in the final synthetic profiles or maps. As an example of the power and versatility of shapemol, we build a model of the molecular envelope of the planetary nebula NGC 6302 and compare it with 12CO and 13CO J = 2-1 interferometric maps from SMA and high-J transitions from Herschel/HIFI. We find the molecular envelope to have a complex, broken ring-like structure with an inner, hotter region and several "fingers" and high-velocity blobs, emerging outwards from the plane of the ring. We derive a mass of 0.11 M⊙ for the molecular envelope. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
50. Astroecology, cosmo-ecology, and the future of life.
- Author
-
Mautner, Michael N.
- Subjects
- *
ASTROBIOLOGY , *METAPHYSICAL cosmology , *ASTEROIDS , *AFTERLIFE , *BIOMASS ,ORIGIN of the solar system - Abstract
Astroecology concerns the relations between life and space resources, and cosmo-ecology extrapolates these relations to cosmological scales. Experimental astroecology can quantify the amounts of life that can be derived from space resources. For this purpose, soluble carbon and electrolyte nutrients were measured in asteroid/meteorite materials. Microorganisms and plant cultures were observed to grow on these materials, whose fertilities are similar to productive agricultural soils. Based on measured nutrient contents, the 1022 kg carbonaceous asteroids can yield 1018 kg biomass with N and P as limiting nutrients (compared with the estimated 1015 kg biomass on Earth). These data quantify the amounts of life that can be derived from asteroids in terms of time-integrated biomass [BIOTAint = biomass (kg) x lifetime (years)], as 1027 kg-years during the next billion years of the Solar System (a thousand times the 1024 kg-years to date). The 1026 kg cometary materials can yield biota 10 000 times still larger. In the galaxy, potential future life can be estimated based on stellar luminosities. For example, the Sun will develop into a white dwarf star whose 1015 W luminosity can sustain a BIOTAint of 1034 kg-years over 1020 years. The 1012 main sequence and white and red dwarf stars can sustain 1046 kg-years of BIOTAint in the galaxy and 1057 kg-years in the universe. Life has great potentials in space, but the probability of present extraterrestrial life may be incomputable because of biological and ecological complexities. However, we can establish and expand life in space with present technology, by seeding new young solar systems. Microbial representatives of our life-form can be launched by solar sails to new planetary systems, including extremophiles suited to diverse new environments, autotrophs and heterotrophs to continually form and recycle biomolecules, and simple multicellulars to jump-start higher evolution. These programs can be motivated by life-centered biotic ethics that seek to secure and propagate life. In space, life can develop immense populations and diverse new branches. Some may develop into intelligent species that can expand life further in the galaxy, giving our human endeavors a cosmic purpose. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
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