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Inamdar, Niraj K. "The formation and evolution of planetary systems". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107104.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (pages 299-311).
The Kepler space observatory and other surveys have revealed thousands of planets and planetary systems that look significantly different from our own. In particular, the preponderance of super-Earths and mini-Neptunes (planets with radii smaller than Neptune's but larger than Earth's) at short orbital radii has challenged planet formation theories developed in the context of our own Solar System. How and where these planets form remains an outstanding question. Given the large frequency with which such planets occur around other stars, understanding the formation pathways of these planets has the potential to reveal dominant mechanisms for planet formation and evolution and to place our own Solar System within a broader context. The purpose of this thesis is to address and develop frameworks by which these questions can be answered. The thesis is comprised of two parts. In Part I, we consider the question of how and where close-in exoplanets formed. We do this in two ways. First, we use that fact that many close-in super-Earths and mini-Neptunes possess gaseous envelopes that comprise several percent or more of the total planet mass in order to construct a self-consistent planet formation history that accounts for core accretion, thermal evolution, and dynamical interactions during the core assembly process via giant impacts. We find that envelope masses accreted from the gas disc by planetary embryos are typically much smaller than those inferred for many exoplanets, and that the envelope mass fraction is further reduced substantially during the assembly phase when embryos merge. Fully assembled planets can accrete observed envelope masses from the residual disc only if energy exchange between the envelope and the underlying core is totally inhibited. It is therefore very unlikely that such planets formed at their observed semimajor axes, but instead formed further out and migrated inwards. Second, we consider the late-stage evolution of exoplanets after gas disc dissipation in order to explain the bulk structural diversity of observed super-Earths and mini-Neptunes. Whereas naive application of core accretion models suggests a narrow mass-radius relationship for these exoplanets, the population possesses a great deal of diversity in mean density. While photoevaporative mass loss from the host star is the most-commonly invoked explanation for this diversity, we use the fact that many exoplanetary systems are in tightly packed orbital configurations to propose instead that late-stage collisions are at least in part responsible for the observed diversity. We infer envelope mass fractions for planets in the literature whose masses and radii have been measured, and on the basis of this, we identify multiplanet systems whose bulk structural diversity favors late-stage impacts as opposed to photoevaporative devolatilization. In Part II, we turn our attention to the formation and evolution of our own Solar System. We do this within the context of NASA's OSIRIS-REx asteroid sample return mission. OSIRIS-REx, which launches in September 2016, will arrive at the near-Earth asteroid 101955 Bennu in 2019 with the objective of constraining its composition, orbit, and other bulk properties. In order to better understand the composition of Bennu, an instrument designed to measure its elemental abundances via X-ray fluorescence spectroscopy called REXIS was developed and built at MIT. In this part of the thesis, we investigate the ability of REXIS to constrain the composition of Bennu via fluorescence spectroscopy, as well as its potential to place Bennu within an analogue meteorite class. We carry out our analysis by modeling Solar X-ray activity and the X-ray fluorescence from Bennu, as well as by simulating data product and analysis from the instrument in order to predict REXIS's ability to carry out its goal of contextualizing Bennu within the asteroid and meteorite population.
by Niraj K. Inamdar.
Ph. D. in Planetary Science
Payne, Matthew John. "On the formation and evolution of planetary systems". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611755.
Pełny tekst źródłaHands, Thomas Oliver. "The enthralling tale of the formation and evolution of compact planetary systems". Thesis, University of Leicester, 2016. http://hdl.handle.net/2381/38766.
Pełny tekst źródłaDavies, Claire L. "Revolution evolution : tracing angular momentum during star and planetary system formation". Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7557.
Pełny tekst źródłaMeng, Huan Y. A., George H. Rieke, Kate Y. L. Su i András Gáspár. "The First 40 Million Years of Circumstellar Disk Evolution: The Signature of Terrestrial Planet Formation". IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623246.
Pełny tekst źródłaTrilling, David Eric. "A theoretical and observational study of the formation and evolution of planetary systems and extrasolar planets". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/288998.
Pełny tekst źródłaNgo, Henry, Heather A. Knutson, Sasha Hinkley, Marta Bryan, Justin R. Crepp, Konstantin Batygin, Ian Crossfield i in. "FRIENDS OF HOT JUPITERS. IV. STELLAR COMPANIONS BEYOND 50 au MIGHT FACILITATE GIANT PLANET FORMATION, BUT MOST ARE UNLIKELY TO CAUSE KOZAI–LIDOV MIGRATION". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621385.
Pełny tekst źródłaPhilipot, Florian. "Vers une recherche exhaustive des planètes géantes autour des étoiles proches de type solaire". Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLO008.
Pełny tekst źródłaThe detection of the first exoplanets in the 1990s opened a new era in the study of planets. Today, thanks to increasingly powerful instruments, several hundred exoplanets (hot Jupiters, Super-Earths, multiple systems...) are discovered every year. Thanks to this wide variety of exoplanets, it is possible to study the distribution (distance, mass, eccentricity...) of these objects in order to better constrain the formation and evolution models of planetary system. Nevertheless, each detection method has its own limitations and detection biases. One aim of this thesis was to identify the limitations of the various detection methods, in particular those related to radial velocities (RV), and to improve the characterization of companions detected by RV.As a first step, I tested the robustness of studies aimed at determining the radial distribution of giant planets. Analysis of RV data from stars hosting long-period planets, the impact of stellar activity and the hypothesis made in completeness calculations, allowed us to demonstrate that statistical RV studies were not robust beyond 7-8 AU. Subsequently, I combined RV data with available absolute and relative astrometry measurements to improve the characterization of long-period sub-stellar companions. This study allowed us to precisely constrain the orbital parameters and, above all, the mass of seven companions detected in RV. It also highlighted the importance of coupling RV data with other measurements to accurately determine the nature of a companion. Finally, I used measurements of stars' proper motion anomalies (PMa), derived from Hipparcos and Gaia absolute astrometry, to search for new sub-stellar companions in the HARPS/VLT spectrograph archive. This analysis enabled me to improve the characterization of 14 sub-stellar companions, and to discover three new brown dwarfs and seven new exoplanets. I also demonstrated the effectiveness of using PMa measurements to optimize the search for sub-stellar companions
Tabera, Martin Luis. "Evolution and properties of planetary systems". Thesis, Uppsala universitet, Observationell astrofysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-438128.
Pełny tekst źródłaBonsor, Amy Hannah Clay. "Post-main sequence evolution of planetary systems". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609856.
Pełny tekst źródłaParai, Rita. "Volatiles in the Earth and Moon: Constraints on planetary formation and evolution". Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11652.
Pełny tekst źródłaEarth and Planetary Sciences
McCormick, David S. "Evolution of an early proterozoic alluvially-dominated foreland basis, Burnside Formation, Kilohigok Basin, N.W.T., Canada". Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/31033.
Pełny tekst źródłaVita.
Includes bibliographical references.
by David Speir McCormick.
Ph.D.
Comito, Carlo. "Numerical N-body approach to binary asteroid formation and evolution". Phd thesis, Université de Nice Sophia-Antipolis, 2012. http://tel.archives-ouvertes.fr/tel-00703696.
Pełny tekst źródłaGerškevitš, Jelena. "Formation and evolution of binary systems with compact objects /". Tartu : Tartu Univ. Press, 2002. http://www.gbv.de/dms/goettingen/389917176.pdf.
Pełny tekst źródłaRein, Hanno. "The effects of stochastic forces on the evolution of planetary systems and Saturn's rings". Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/237379.
Pełny tekst źródłaBecker, John Alex 1964. "Formation and evolution of hypernova progenitors in massive binary systems". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28373.
Pełny tekst źródłaIncludes bibliographical references (p. 159-170).
The massive stellar progenitor of a hypernova explosion and an associated gamma-ray burst must satisfy two primary constraints: (1) the outer layers of the stellar core must possess sufficient angular momentum to form a centrifugally supported torus about the collapsed central object (a Kerr black hole); and, (2) the envelope of the star must not be excessively massive or distended, so that the energetic, ultrarelativistic outflow generated by the central engine in the core of the star does not risk being smothered before it can escape from the star and expand outward to produce a gamma-ray burst. Physical processes which occur during the evolution of an isolated massive star will tend to diminish its initial angular momentum content, rendering it difficult for such a star to become a hypernova progenitor since its core will likely no longer spin rapidly enough to support a torus about its collapsed core. However, a substantial fraction of massive stars are members of binary systems. Tidal locking, mass transfer, or stellar merger in an evolved massive binary system could possibly lead to the transfer of orbital angular momentum to the core of one of the stars (or to the core of a merged star, if a common envelope develops), of sufficient magnitude to produce the core of a successful hypernova progenitor (constraint 1). Further interaction between the stars or their compact remnants could lead to the loss of the hydrogen and possibly helium envelopes of one of the stars (constraint 2). We have developed a new one-dimensional stellar evolution code that includes the effects of rotation on equilibrium stellar structure, and calculates the transport of angular momentum through the stellar interior due to convection, dynamical and secular shear instabilities, and gravity (buoyancy) waves.
(cont.) We have used this code to calculate a variety of evolutionary sequences involving the transfer of mass from one component of the binary system to the other. We have also calculated an evolutionary sequence ending in the merger of one component of the system with the core of the other, induced by a prior common-envelope phase. We find that over a wide range of initial binary system parameters, the initially less massive component of the system can accrete a substantial amount of mass and angular momentum from the initially more massive component. The accreted angular momentum is efficiently transported inward from the surface of the accreting star toward its core by a combination of convection and dynamical and secular shear instabilities. If accretion commences while the accretor is still on the main sequence, we find that the inward-progressing wave of angular momentum can penetrate the core of the mass-gaining star, contributing to its store of rotational angular momentum without the need for gravity wave transport of angular momentum across the core- envelope interface. These stars end their evolution (just prior to core carbon ignition) as red supergiants, with cores endowed with sufficient angular momentum to give rise to a hypernova explosion. We also find that a subsequent common-envelope phase with the compact remnant of the primary might result in the ejection of the accretor's red-giant envelope, leaving either a bare helium or carbon-oxygen star. Such a star would be expected to explode in a Type lb or Ic supernova/hypernova.
by John Alex Becker.
Ph.D.
Brown, David John Alexander. "The effects of tidal interactions on the properties and evolution of hot-Jupiter planetary systems". Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/4181.
Pełny tekst źródłaMagalhaes, Victor de Souza. "The protosolar nebula heritage : the nitrogen isotopic ratio from interstellar clouds to planetary systems". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY095/document.
Pełny tekst źródłaThe existence of interstellar molecules raises the question, are thesemolecules the same molecules we see on the Solar system today? Thisis still an open question with far reaching consequences. Some lightmay be shed on this issue if we are able to trace the heritage of agroup of chemically linked molecules, a so-called reservoir. The besttool to trace the heritage of reservoirs are isotopic ratios. The elementthat shows the largest isotopic ratio variations in the Solar system isnitrogen. For this is an indication that the isotopic ratio of nitrogen issensitive to the physical conditions during star formation.The main objective of this thesis is to identify the reservoirs of ni-trogen at different stages of star and planet formation. The first stepin this endeavour was to identify the isotopic ratio of the bulk of ni-trogen in the local ISM today. This was determined to be 323 ± 30from the CN/C 15 N ratio in the protoplanetary disk around TW Hya.Along with it we also measured the HCN/HC 15 N= 128 ± 36 in theprotoplanetary disk around MWC 480. This very distinct nitrogen iso-topic ratios on protoplanetary disks are a clear indication that thereare at least two reservoirs of nitrogen in protoplanetary disks. Howthese reservoirs get separated is however unknown. This could pos-sibly happen due to chemical fractionation reactions taking place inprestellar cores. We therefore aimed to obtain an accurate direct mea-surement of the nitrogen isotopic ratio of HCN in the prestellar coreL1498.To obtain this measurement the most important hurdle to overcomewere the hyperfine anomalies of HCN. These hyperfine anomaliesarise due to the overlap of hyperfine components. They are especiallysensitive to the column density of HCN, but also to the velocity fieldand line widths. Thus hyperfine anomalies are a tool to measure theabundance of HCN and to probe the kinematics of prestellar cores.To accurately reproduce the hyperfine anomalies, and thus mea-sure accurate column densities for HCN, we needed to explore adegenerate parameter space of 15 dimensions. To minimise the de-generacies we have derived a density profile based on continuummaps of L1498. This reduced the parameter space to 12 dimensions.The exploration of this parameter space was done through the useof a MCMC minimisation method. Through this exploration we ob-tained HCN/HC 15 N = 338 ± 28 and HCN/H 13 CN = 45 ± 3. Theuncertainties on these values are calibration limited and determinednon-arbitrarily by the MCMC method. Implications of these resultsare discussed in the concluding chapter, where we also present somefuture perspectives
Mark, Hannah F. "Seismic and numerical constraints on the formation and evolution of ocean lithosphere". Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/127722.
Pełny tekst źródłaCataloged from PDF of thesis.
Includes bibliographical references (pages 151-174).
This thesis explicates aspects of the basic structure of oceanic lithosphere that are shaped by the processes that form the lithosphere. The strength of lithospheric plates relative to the underlying mantle enables the surface plate motions and plate boundary processes that characterize plate tectonics on Earth. Surprisingly, we have a relatively poor understanding of the physical mechanisms that make the lithosphere strong relative to the asthenosphere, and we lack a reference model for ordinary lithospheric structure that can serve as a baseline for comparing geophysical observations across locations. Chapters 2 and 3 of this thesis investigate the seismic structure of a portion of the Pacific plate where the simple tectonic history of the plate suggests that its structure can be used as a reference model for oceanic lithosphere. We present measurements of shallow azimuthal seismic anisotropy, and of a seismic discontinuity in the upper mantle, that reflect the effects of shear deformation and melting processes involved in the formation of the lithosphere at mid-ocean ridges. Chapter 4 uses numerical models to explore factors controlling fault slip behavior on normal faults that accommodate tectonic extension during plate formation.
by Hannah F. Mark.
Ph. D.
Ph.D. Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution)
Roberts, Daniel Thomas. "A geomechanical analysis of the formation and evolution of Polygonal Fault Systems". Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/72000/.
Pełny tekst źródłaLyra, Wladimir. "Turbulence-Assisted Planetary Growth : Hydrodynamical Simulations of Accretion Disks and Planet Formation". Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9537.
Pełny tekst źródłaGaspar, Andras. "Observations and Models of Infrared Debris Disk Signatures and their Evolution". Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202982.
Pełny tekst źródłaWilson, Robert F., Johanna Teske, Steven R. Majewski, Katia Cunha, Verne Smith, Diogo Souto, Chad Bender i in. "Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances". IOP PUBLISHING LTD, 2018. http://hdl.handle.net/10150/626528.
Pełny tekst źródłaMulders, Gijs D., Ilaria Pascucci, Dániel Apai, Antonio Frasca i Joanna Molenda-Żakowicz. "A SUPER-SOLAR METALLICITY FOR STARS WITH HOT ROCKY EXOPLANETS". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622435.
Pełny tekst źródłaHorning, Gregory (Gregory William). "Geophysical and geochemical constraints on the evolution of oceanic lithosphere from formation to subduction". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108908.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (pages 104-115).
This thesis investigates the evolution of the oceanic lithosphere in a broad sense from formation to subduction, in a focused case at the ridge, and in a focused case proximal to subduction. In general, alteration of the oceanic lithosphere begins at the ridge through focused and diffuse hydrothermal flow, continues off axis through low temperature circulation, and may occur approaching subduction zones as bending related faulting provides fluid pathways. In Chapter 2 1 use a dataset of thousands of microearthquakes recorded at the Rainbow massif on the Mid-Atlantic Ridge to characterize the processes which are responsible for the long-term, high-temperature, hydrothermal discharge found hosted in this oceanic core complex. I find that the detachment fault responsible for the uplift of the massif is inactive and that the axial valleys show no evidence for faulting or active magma intrusion. I conclude that the continuous, low-magnitude seismicity located in diffuse pattern in a region with seismic velocities indicating ultramafic host rock suggests that serpentinization may play a role in microearthquake generation but the seismic network was not capable of providing robust focal mechanism solutions to constrain the source characteristics. In Chapter 3 I find that the Juan de Fuca plate, which represents the young/hot end-member of oceanic plates, is lightly hydrated at upper crustal levels except in regions affected by propagator wakes where hydration of lower crust and upper mantle is evident. I conclude that at the subduction zone the plate is nearly dry at upper mantle levels with the majority of water contained in the crust. Finally, in Chapter 4 I examine samples of cretaceous age serpentinite sampled just before subduction at the Puerto Rico Trench. I show that these upper mantle rocks were completely serpentinized under static conditions at the Mid-Atlantic Ridge. Further, they subsequently underwent 100 Ma of seafloor weathering wherein the alteration products of serpentinization themselves continue to be altered. I conclude that complete hydration of the upper mantle is not the end point in the evolution of oceanic lithosphere as it spreads from the axis to subduction.
by Gregory Horning.
Ph. D.
Pippin, Charles Everett. "Trust and reputation for formation and evolution of multi-robot teams". Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50376.
Pełny tekst źródłaRAGUSA, ENRICO. "THE EVOLUTION OF BINARY SYSTEMS IN GASEOUS ENVIRONMENTS". Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/604177.
Pełny tekst źródłaPetit, Antoine. "Architecture et stabilité des systèmes planétaires". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEO005.
Pełny tekst źródłaThe architecture of a planetary systems is a signpost of their formation and history.Moreover, the large number of recent and future exoplanets discoveries allows to study the exoplanet system population.Besides, the observations of exoplanet systems has enriched the diversity of planetary system architecture, revealing that the Solar System shape is far from being the norm.However, the organization of planetary systems is heavily affected by dynamical stability, making individual studies particularly challenging.Since planets dynamics are chaotic, a detailed stability analysis study is computationally expensive.In this thesis, I develop analytic stability criteria for planet dynamics.In the secular system, the conservation of the total angular momentum and semi-major axes imply the conservation of the Angular Momentum Deficit (AMD).The AMD is a measure of a system’s eccentricities and mutual inclinations and act as a dynamical temperature of the system.Based on this consideration, we make the simplifying assumption that the dynamics can be replaced by AMD exchanges between the planets.In the first chapter we define the concept of AMD-stability. The AMD-stability criterion allows to discriminate between a priori stable planetary systems and systems for which the stability is not granted and needs further investigations.We show how AMD-stability can be used to establish a classification of the multiplanet systems in order to exhibit theplanetary systems that are long-term stable because they are AMD-stable, and those that are AMD-unstable which then require someadditional dynamical studies to conclude on their stability. We classify 131 multiplanet systems from the exoplanet.eu database with sufficiently well-known orbital elements.While the AMD criterion is rigorous, AMD conservation is only granted in absence of mean-motion resonances (MMR).If the MMR islands overlap, the system experiences chaos leading to instability.In the second chapter, we extend the AMD-stability criterion to take into account the overlap of first-order MMR.I derive analytically a new overlap criterion for first-order MMR.This stability criterion unifies the previous criteria proposed in the literature and admits the criteria obtained for initially circular and eccentric orbits as limit cases.In the third chapter I explain how the Hill stability can be understood in the AMD framework.Widely used, the Hill stability is a topological stability criterion for the three body system.However, most studies only use the coplanar and circular orbit approximation.We show that the general Hill stability criterion can be expressed as a function of only semi-major axes, masses, and total AMD of the system.The proposed criterion is only expanded in the planets-to-star mass ratio and not in the orbital elements.When studying AMD-unstable system, numerical simulations are mandatory.However the long timescales in planet dynamics make necessary the use of symplectic methods.These methods provide very accurate and fast integration when a system is stable.Their downside is that they are limited to fixed time-step integration.For unstable systems, the integrator may fail to resolve a close encounter and become inaccurate.In the fourth chapter, I propose a time renormalization that allow to use high order symplectic integrator with adaptive time-step at close encounter.The algorithm is well-adapted to systems of few similar masses planets.In the final chapter, I revisit the planet formation toy model developed by J. Laskar.While the AMD is conserved in the secular dynamics, it decreases during planets collisions.Laskar's model can be solved analytically for the average outcome and numerical simulations are very quick allowing to build large system population.I show that this formation model is in good agreement with recent realistic planet formation simulations where the final architecture results from a giant impact phase
Bockelée-Morvan, Dominique, J. Crovisier, S. Erard, F. Capaccioni, C. Leyrat, G. Filacchione, P. Drossart i in. "Evolution of CO2, CH4, and OCS abundances relative to H2O in the coma of comet 67P around perihelion from Rosetta/VIRTIS-H observations". OXFORD UNIV PRESS, 2016. http://hdl.handle.net/10150/624745.
Pełny tekst źródłaZurlo, Alice. "Characterization of exoplanetary systems with the direct imaging technique : towards the first results of SPHERE at the Very Large Telescope". Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4721/document.
Pełny tekst źródłaIn the year of the 20th anniversary of the discovery of the first extrasolar planet we can count more than 1800 companions found with different techniques. The majority of them are indirect methods that infer the presence of an orbiting body by observing the parent star (radial velocity, transits, astrometry). In this work we explore the technique that permits to directly observe planets and retrieve their spectra, under the conditions that they are bright and far enough from their host star. Direct imaging is a new technique became possible thanks to a new generation of extreme adaptive optics instruments mounted on 8m class telescopes. On the Very Large Telescope two instruments dedicated to the research for exoplanets with direct imaging are now operative: NACO and SPHERE. This thesis will describe the development and results of SPHERE from its predecessor NACO to its integration in laboratory and the final on sky results
Allen, Christopher J. T. "Atmospheric mechanisms of central Saharan dust storm formation in boreal summer : observations from the Fennec campaign". Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:896c26f3-c7a5-4c93-9e53-69b69b28d1cb.
Pełny tekst źródłaMendes, Luana Liberato. "Estabilidade e formação de planetas terrestres em regiões coorbitais /". Guaratinguetá, 2019. http://hdl.handle.net/11449/181758.
Pełny tekst źródłaResumo: Encontrar um planeta como a Terra fora do Sistema Solar parece ser dificil. Quando olhamos para os dados dos quase 4000 exoplanetas descobertos até o momento vemos que nenhum deles é similar à Terra. Uma alternativa para encontrar um outro planeta como a Terra seria olhar para as regiões coorbitais dos exoplanetas gigantes, sendo que sistemas coorbitais podem ser descritos como os sistemas onde dois ou mais corpos compartilham uma mesma órbita média. Nosso objetivo neste trabalho é formar um planeta com a massa da Terra que seja coorbital a um corpo bastante massivo, como um planeta gigante ou uma anã marrom. Para isso nós fizemos várias simulações utilizando o pacote Mercury de integração numérica para o problema de N-corpos. Com os resultados analisamos como a razão de massa do sistema e a separação entre os corpos afetam a região de estabilidade coorbital, e então determinamos seus limites radial e angular. Tendo a região de estabilidade coorbital bem definida para cada um dos sistemas estudados, nós fizemos novas simulações numéricas distribuindo dentro da região de estabilidade coorbital 500 planetesimais que cujas massas somadas totalizam 2 ou 3M⊕. Nossos resultados mostraram que é possível formar planetas terrestres com massas iguais ou maiores que a da Terra nas regiões coorbitais. Esta formação é mais provável para os sistemas cujo corpo secundário possui uma órbita com semi-eixo maior menor que 1ua, sendo que os diferentes valores de razão de massa não afetam o proc... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Finding an Earth-like planet outside Solar System seems to be a difficult task. When we look at the data from the almost 4000 exoplanets discovered until now we see that none of them is similar to our Earth. An alternative to find other planet like Earth would be to look at the co-orbital regions of the giants exoplanets, being that co-orbital systems can be described as those systems where two or more bodies share the same mean orbit. Our main goal in this work is to form a planet co-orbiting with another massive body, like a giant planet, with the same mass of the Earth. To do that we have performed a series of numerical simulations with the package of computational integrators for the N-body problem called Mercury. With the results we have analyzed how the stable co-orbital region is affected by the system’s mass ratio and by the radial separation between bodies, and then we have determined the radial and angular limits of the stable co-orbital region. Having this region well determined for each one of the studied systems, we have performed new numerical simulations distributing 500 planetesimals within the stable co-orbital region, in which the sum of the planetesimals’s masses are equal to 2 or 3MEarth. Our results have shown that it is possible to form terrestrial planets with masses equals or bigger than the Earth’s inside the stable co-orbital regions. This formation is more likely to happen for the systems in which the secondary body has an orbit with semi-major axis... (Complete abstract click electronic access below)
Mestre
Romans, Brian William. "Controls on distribution, timing, and evolution of turbidite systems in tectonically active settings : the cretaceous Tres Pasos Formation, southern Chile, and the Holocene Santa Monica Basin, California /". May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Pełny tekst źródłaZurlo, Alice. "Characterization of exoplanetary systems with the direct imaging technique: towards the first results of SPHERE at the Very Large Telescope". Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424178.
Pełny tekst źródłaAl giorno d'oggi più di 1800 pianeti sono stati scoperti orbitare attorno a stelle al di fuori del sistema solare. Le tecniche utilizzate per la ricerca di pianeti extrasolari sono molteplici: alcune, dette metodi indiretti, si basano sull'osservazione della perturbazione indotta dal pianeta orbitante sulla stella ospite, mentre altre si basano sull'osservazione diretta del pianeta stesso. La maggior parte dei pianeti scoperti attualmente é stata rivelata grazie ai primi. Specialmente il metodo delle velocità radiali e dei transiti hanno fornito il più alto numero si scoperte. Lo svantaggio di questo tipo di tecniche é che la caratterizzazione del pianeta non può essere completa a meno che non vengano usate simultaneamente più tecniche. Inoltre, per ottenere lo spettro del pianeta, quest'ultimo deve transitare e anche in questo caso il segnale é difficilmente estrapolabile. L'osservazione diretta di questi oggetti, detta “direct imaging”, é oggi possibile grazie ad avanzati sistemi di ottica adattiva installati su telescopi della classe 8m. Il direct imaging permette l'osservazione diretta di pianeti sufficientemente luminosi e distanti dalla stella ospite grazie ad una maschera che oscura la luce di quest'ultima. Questa tecnica quindi é particolarmente efficiente su sistemi giovani e vicini, dato che la luminosità intrinseca del pianeta diminuisce con l'età e che la separazione effettiva del pianeta dipende dalla distanza del sistema stesso. Sul Very Large Telescope a Paranal (Chile) due strumenti sono dedicati a questo tipo di ricerca: NACO e SPHERE. NACO é stato pensato come predecessore e prototipo di SPHERE, ma viene mantenuto grazie alle sue performance ancora competitive ed ad alcune caratteristiche che non sono presenti in SPHERE. SPHERE ha visto la sua prima luce in Maggio 2014 ed é ora pronto per cominciare una survey dedicata alla scoperta di pianeti attorno a sistemi giovani e vicini, NISUR. Questo strumento é composto da tre sottosistemi: IRDIS, IFS e ZIMPOL. IRDIS é una camera infrarossa cui detector é suddiviso in due porzioni uguali per sfruttare l'immagine simultanea del target in due filtri adiacenti. IFS é lo spettrografo di SPHERE, permette di estrarre lo spettro del pianeta con risoluzioni di 30 e 50 a seconda della banda spettrale utilizzata. ZIMPOL é l'unico sottosistema che lavora nel visibile, viene utilizzato per osservare la polarizzazione dei sistemi planetari. In questo lavoro viene presentato lo strumento SPHERE e il suo predecessore NACO, focalizzando sui risultati e sulle performance nella caratterizzazione dei sistemi planetari.
Cossou, Christophe. "Effet de la structure du disque sur la formation et la migration des planètes". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00949904.
Pełny tekst źródłaMawet, Dimitri, Élodie Choquet, Olivier Absil, Elsa Huby, Michael Bottom, Eugene Serabyn, Bruno Femenia i in. "CHARACTERIZATION OF THE INNER DISK AROUND HD 141569 A FROM KECK/NIRC2 L-BAND VORTEX CORONAGRAPHY". IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625206.
Pełny tekst źródłaBenbakoura, Mansour. "Evolution des étoiles de faible masse en interaction : observations multi-techniques et modélisation des systèmes multiples". Thesis, Université de Paris (2019-....), 2019. http://www.theses.fr/2019UNIP7027.
Pełny tekst źródłaThis thesis is devoted to the study of low-mass stars having other stars or planets in their immediate environment. We focused on the influence of interactions with these companions on stellar evolution and their observable consequences.In the first part, we present the model of evolution of star–planet systems that we developed during this thesis, called ESPEM (French acronym for Evolution of Planetary Systems and Magnetism). This model incorporates ab-initio prescriptions to quantify the effects of magnetized stellar wind and tidal dissipation on stellar rotation and planetary orbit, simultaneously with the star's structural evolution. First, we use it to study the secular evolution of the rotation of planet-host stars and show that this evolution can be significantly different from that of isolated stars. Next, we examine the predictions of this model regarding the orbital architecture of star–planet systems. Our results suggest an interpretation to the observed distributions of orbital and stellar rotation periods.In the second part of the manuscript, we show how the observation of advanced binary stars allows us to test astrophysical theories, in particular asteroseismology and tidal interaction. First, we present the results of an observation program that we conducted for more than two years and that allowed us to characterize 16 eclipsing binary systems. Then, we compare these results with those obtained by analyzing this sample using asteroseismic tools to verify the accuracy of the latter. Finally, by extending the studied sample to 30 other advanced binary stars including an evolved primary, we test the theory of tidal evolution. This allows us both to validate the theory and to understand the evolution of the systems observed in this work.This work highlights two aspects of the specificity of multiple systems. First, it shows how the evolution of stars is affected by the presence of a stellar or planetary companion. Second, it emphasizes the interest of binary stars in testing astrophysical theories and reinforces the current understanding of stellar evolution
Neves, Vasco. "Étude sur les paramétres stellaires des naines M et leur lien à la formation planétaire". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY082/document.
Pełny tekst źródłaAt the time of writing of this Thesis more than 900 planets have been announced and about 2700 planets from the Kepler space telescope are waiting to be confirmed. The very precise spectra and light curves obtained in Doppler and transit surveys, allows the in-depth study of the parameters of the host stars, and opens the possibility to investigate the star-plant correlations. Also, determining the stellar parameters with precision is critical for more precise determinations of the planetary parameters, namely, mass, radius, and density.In the case of the FGK dwarfs, the determination of stellar parameters is well established and can be used with confidence to study the star-planet relation as well as to obtain precise planetary parameters. However, this is not the case for M dwarfs, the most common stars in the Galaxy. Compared to their hotter cousins, M dwarfs are smaller, colder, and fainter, and therefore harder to study. The biggest challenge regarding M dwarfs is related to the presence of billions of molecular lines that depress the continuum making a classical spectral analysis almost impossible. Finding new and innovative ways to overcome this obstacle in order to obtain precise stellar parameters is the goal of this Thesis.To achieve this goal I focused my research into two main avenues: photometric and spectroscopic methods. My initial work had the objective of establishing a precise photometric metallicity calibration, but I could not reach this goal, as I did not have enough FGK+M binaries with good photometric data. However, it was possible, with the available data, to compare the already established photometric calibrations and slightly improve the best one, as described in Chapter 3.Then, I focused on spectroscopic approaches with the aim of obtaining precise M dwarf parame- ters. To this end I used HARPS high-resolution spectra and developed a method to measure the spectral lines disregarding the continuum completely. Using this method I established a new visible calibration with a precision of 0.08 dex for [Fe/H] and 80 K for Te f f . This work is detailed in Chapter 4.Finally, I also participated in the refinement of the parameters of the star GJ3470 and its planet, where my expertise in stellar parameters of M dwarfs had an important role. The details regarding this investigation are shown in Chapter 5
No momento em que escrevo esta Tese, o número de planetas anunciados já ultrapassou os 900 e os cerca de 2700 candidatos detectados pelo telescópio espacial Kepler esperam por confirmação. Os espectros e as curvas de luz obtidos nos programas de procura de planetas permitem, também, o estudo em profundidade dos parâmetros das estrelas com planetas e abrem a possibilidade de investigar a relação estrela-planeta. Neste contexto, a determinação com precisão dos parâmetros estelares é crítica na determinação precisa dos parâmetros planetários, nomeadamente, a massa, o raio e a densidade.No caso das anãs FGK, os métodos de determinação dos parâmetros estelares estão bem estabelecidos e podem ser usados com confiança no estudo da relação estrela-planeta, assim como na obtenção de parâmetros planetários precisos. No entanto, não é esse o caso para as anãs M, as estrelas mais comuns da nossa Galáxia. Ao contrário das suas primas, as estrelas M são mais pequenas, frias e ténues e, assim sendo, mais difíceis de estudar. O grande entrave no estudo das estrelas M está relacionado com a presença de biliões de linhas moleculares que deprimem o contínuo espectral, fazendo com que uma análise espectral clássica se torne quase impossível. A procura de métodos inovadores que possibilitem ultrapassar este obstáculo, tendo em vista a obtenção de parâmetros precisos, é o objectivo desta Tese.Tendo em conta esse objetivo, foquei os meus esforços em duas linhas principais de pesquisa, baseadas em métodos fotométricos e métodos espectroscópicos. O meu trabalho inicial tinha como objetivo o estabelecimento de uma calibração fotométrica para a metalicidade, mas não me foi possível atingir esse objetivo, pois não tinha sistemas binários FGK+M suficientes com bons dados fotométricos. No entanto, foi possível, com os dados disponíveis, comparar as calibrações fotométricas existentes e refinar ligeiramente a melhor delas, como descrito no Capítulo 3.Após este trabalho passei a concentrar-me em técnicas espectroscópicas de obtenção de parâmetros estelares em estrelas M. Tendo em mente esse objetivo, usei espectros HARPS de alta resolução para desenvolver um novo método de medição de linhas espectrais independente do contínuo espectral. Seguidamente, usei este método no desenvolvimento de uma nova calibração de metalicidade e temperatura efectiva em estrelas M na região do visível, através da qual consegui atingir uma precisão de 0.08 dex para a [Fe/H] e de 80 K para a temperatura. Este trabalho está descrito no Capítulo 4.Ao mesmo tempo colaborei na determinação com precisão dos parâmetros da estrela GJ3470 e do seu planeta, onde a minha proficiência na determinação de parâmetros estelares em anãs M teve um papel importante. Os detalhes relacionados com este trabalho de investigação estão descritos no Capítulo 5
Lebreton, Jérémy. "Observations et modélisation des systèmes planétaires autour des étoiles proches". Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00952803.
Pełny tekst źródłaOrtiz, Mauricio, Sabine Reffert, Trifon Trifonov, Andreas Quirrenbach, David S. Mitchell, Grzegorz Nowak, Esther Buenzli i in. "Precise radial velocities of giant stars". EDP SCIENCES S A, 2016. http://hdl.handle.net/10150/622444.
Pełny tekst źródłaKollmeier, Juna Ariele. "The intergalactic medium absorption, emission, disruption /". Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1153856075.
Pełny tekst źródłaLaporte, Nicolas. "Recherche et étude des premières galaxies". Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00781144.
Pełny tekst źródłaGarcia, Thomas. "Déterminants évolutionnistes de la socialité : le rôle de la formation de groupe". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-01018209.
Pełny tekst źródłaSaker, Leila Yamila. "Material circunestelar en estrellas de tipo enanas blancas". Doctoral thesis, 2020. http://hdl.handle.net/11086/23533.
Pełny tekst źródłaSe han descubierto discos de gas en un grupo de enanas blancas con discos de polvo, a través de la detección en sus espectros de lineas de emisión inusuales del triplete de Ca II en 8600 Å. En este contexto, se han obtenido espectros ópticos GMOS/GEMINI para 13 enanas blancas con excesos IR, seleccionados de nuestra muestra de 29 estrellas con discos “debris”, con el objetivo de encontrar la contraparte gaseosa a los discos de polvo. Se presenta además un estudio comparativo de las principales propiedades físicas y de parámetros relacionados al disco de polvo de las enanas blancas con y sin discos de gas detectados. Adicionalmente, se aplicó la técnica de “Eclipse Timing Variation” en una muestra de 8 sistemas binarios eclipsantes formados por enana blanca+estrella de secuencia principal con el objetivo de detectar planetas circumbinarios. Para ello, se obtuvieron observaciones propias con los telescopios argentinos localizados en la Estación Astrofísica de Bosque Alegre y el telescopio Jorge Sahade en el Complejo Astronómico El Leoncito. Las curvas de luz obtenidas, fueron complementadas con las disponibles en las bases de datos del “Catalina Sky Survey” y Kepler+K2. Los tiempos de mínimo fueron obtenidos con el código Wilson & Devinney.
Gas disks have been discovered in a group of white dwarfs with dust disks, through the detection in their spectra of unusual emission lines of the triplet of Ca II at 8600 Å. In this context, GMOS/GEMINI optical spectra have been obtained for 13 white dwarfs with IR excesses, selected from our sample of 29 stars with debris disks, with the aim to find the gaseous counterpart to the dusty disks. We also present a comparative study of the main physical properties and parameters related to the dusty disk of white dwarfs with and without gas disks detected. Additionally, the Eclipse Timing Variation technique was applied in a sample of 8 eclipsing binary systems formed by white dwarf + main sequence star, with the aim to detect circumbinary planets. For this, own observations were obtained with the Argentine telescopes located in the Estación Astrofísica de Bosque Alegre and the Jorge Sahade telescope in the Complejo Astronómico El Leoncito. The light curves obtained were complemented with those available in the databases "Catalina Sky Survey" and Kepler+K2. Minimum times were obtained with the Wilson & Devinney code.
Fil: Saker, Leila Yamila. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.
Brugamyer, Erik John. "Silicon and oxygen abundances in planet-host stars". Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2303.
Pełny tekst źródłatext
SHERIDAN, EMILY. "Dynamical Evolution and Growth of Protoplanets Embedded in a Turbulent Gas Disk". Thesis, 2009. http://hdl.handle.net/1974/5163.
Pełny tekst źródłaThesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-17 14:41:52.607
Mudryk, Lawrence Russell. "Planetary system evolution: Planet-disk interactions and planet ejection from binary systems". 2007. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=742500&T=F.
Pełny tekst źródłaCarelli, Fabio. "Molecular anions in circumstellar envelopes, interstellar clouds and planetary atmospheres: quantum dynamics of formation and evolution". Doctoral thesis, 2011. http://hdl.handle.net/11573/918878.
Pełny tekst źródłaKratter, Kaitlin Michelle. "Accretion Disks and the Formation of Stellar Systems". Thesis, 2010. http://hdl.handle.net/1807/26283.
Pełny tekst źródła"The Diversity of Chemical Composition and the Effects on Stellar Evolution and Planetary Habitability". Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.45482.
Pełny tekst źródłaDissertation/Thesis
Doctoral Dissertation Astrophysics 2017