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Mysteres De La Formation Des Galaxies
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Book Synopsis Mystères de la formation des galaxies by : Françoise Combes
Download or read book Mystères de la formation des galaxies written by Françoise Combes and published by Dunod. This book was released on 2008-04-02 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Une galaxie est un ensemble d'étoiles (environ une centaine de milliards), cohabitant avec du gaz et de la poussière. L'ensemble des galaxies (plusieurs milliards) et la nature de leur rayonnement témoignent de l'expansion de l'Univers. Selon les dernières recherches, les galaxies n'auraient pas toujours eu la même morphologie. En effet, l'Univers au tout début de sa formation, était très différent de l'Univers que les astronomes observent actuellement. C'est à cette époque que de nombreuses petites galaxies se sont formées, les «bébés-galaxies». L'auteur nous explique la naissance, l'histoire et l'évolution de ces bébés-galaxies. Des paradoxes apparaissent car les observations ne sont pas toujours en accord avec les modèles simulés. Plusieurs scénarios sont envisagés pour expliquer ces paradoxes, parmi lesquelles un changement des lois de la gravitation.
Download or read book Les galaxies written by Danielle Alloin and published by FeniXX. This book was released on 1998-01-01T00:00:00+01:00 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cent milliards de galaxies environ peuplent l’Univers. Depuis le début des années 60, les astrophysiciens tentent de percer le mystère de leur formation. Danielle Alloin, directeur de recherches au CNRS, fait l’état des connaissances disponibles sur le sujet : leurs composants (étoiles, matière interstellaire, trous noirs), leurs formes diverses, leur interaction gravitationnelle. Mais l’homme considère déjà les galaxies comme des objets familiers. Aurait-il dès aujourd’hui modifié la conception de sa place dans l’espace et le temps ?
Book Synopsis Finding Our Place in the Universe by : Helene Courtois
Download or read book Finding Our Place in the Universe written by Helene Courtois and published by MIT Press. This book was released on 2019-05-28 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: How a team of researchers, led by the author, discovered our home galaxy's location in the universe. You are here: on Earth, which is part of the solar system, which is in the Milky Way galaxy, which itself is within the extragalactic supercluster Laniakea. And how can we pinpoint our location so precisely? For twenty years, astrophysicist Hélène Courtois surfed the cosmos with international teams of researchers, working to map our local universe. In this book, Courtois describes this quest and the discovery of our home supercluster. Courtois explains that Laniakea (which means “immense heaven” in Hawaiian) is the largest galaxy structure known to which we belong; it is huge, almost too large to comprehend—about five hundred million light-years in diameter. It contains about 100,000 large galaxies like our own, and a million smaller ones. Writing accessibly for nonspecialists, Courtois describes the visualization and analysis that allowed her team to map such large structures of the universe. She highlights the work of individual researchers, including portraits of several exceptional women astrophysicists—presenting another side of astronomy. Key ideas are highlighted in text insets; illustrations accompany the main text. The French edition of this book was named the Best Astronomy Book of 2017 by the astronomy magazine Ciel et espace. For this MIT Press English-language edition, Courtois has added descriptions of discoveries made after Laniakea: the cosmic velocity web and the Dipole and Cold Spot repellers. An engaging account of one of the most important discoveries in astrophysics in recent years, her story is a tribute to teamwork and international collaboration.
Book Synopsis Les mystères de l’espace by : Khalid Jerrari
Download or read book Les mystères de l’espace written by Khalid Jerrari and published by Khalid Jerrari. This book was released on 2015-02-02 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: De nombreuses recherches restées infructueuses tentent d’expliquer l’univers qui nous entoure par la présence de matières inconnues et d’énergies mystérieuses toujours introuvables. Mais alors ne serait-il pas temps de considérer d’autres hypothèses ? Dans cet ouvrage pédagogique et à la portée d’un large public visant à expliquer la « Théorie spatiale », l’auteur présente une réflexion philosophique suivie d’une explication scientifique sur l’influence de l’espace sur notre univers, l’espace étant considéré ici comme une substance physique. Pour son premier ouvrage scientifique, Khalid Jerrari s’affiche sans doute comme le premier auteur à « vulgariser » ses propres recherches scientifiques dans le but de les rendre accessibles à un public non scientifique. En reprenant pas-à-pas quelques lois de la physique et en expliquant certains grands principes universels, son livre propose une théorie qui unifie les lois de la cosmologie.
Download or read book Les galaxies written by Danielle Alloin and published by . This book was released on 1998 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cent milliards de galaxies environ peuplent l'univers. Depuis le début des années 60, les astrophysiciens tentent de percer le mystère de leur formation. Danielle Alloin, directeur e recherches au CNRS, fait l'état des connaissances disponibles sur le sujet : leurs composantes (étoiles, matière interstellaire, trous noirs), leurs formes diverses, leur interaction gravitationnelle. Mais l'homme considère déjà les galaxies comme des objets familiers. Aurait-il dès aujourd'hui modifié la conception de sa place dans l'espace et le temps ?
Book Synopsis The Birth of the Universe by : J. AUDOUZE (Ed)
Download or read book The Birth of the Universe written by J. AUDOUZE (Ed) and published by Atlantica Séguier Frontières. This book was released on 1982 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Origine et formation des mondes by : abbé Théophile Moreaux
Download or read book Origine et formation des mondes written by abbé Théophile Moreaux and published by . This book was released on 1925 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Les galaxies written by Sophie Koechlin and published by Deux Coqs d'or. This book was released on 2022-03-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Retrouve tout ce que tu as toujours voulu savoir sur les galaxies : leur formation, leurs secrets et leur évolution ... sans oublier de quoi est constitué la Voie lactée. Découvre la carte du ciel et l'évolution des connaissances scientifiques, de la niassance du Big Bang à la mission Gaia !
Book Synopsis Formation Des Galaxies by : Marie Martig
Download or read book Formation Des Galaxies written by Marie Martig and published by . This book was released on 2010 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is devoted to galaxy formation and evolution in a cosmological context. Cosmological simulations have unveiled two main modes of galaxy growth: hierarchical growth by mergers and accretion of cold gas from cosmic filaments. However, these simulations rarely take into account small scale mechanisms, that govern internal evolution and that are a key ingredient to understand galaxy formation and evolution. Thanks to a new simulation technique that I have developed, I first studied the colors of galaxies, and in particular the reddening of elliptical galaxies. I showed that the gas disk in an elliptical galaxy could be stabilized against star formation because of the galaxy's stellar component being within a spheroid instead of a disk. This mechanism can explain the red colors of some elliptical galaxies that contain a gas disk. I also studied the formation of spiral galaxies: most cosmological simulations cannot explain the formation of Milky Way-like galaxies, i.e. with a large disk and a small bulge. I showed that this issue could be partly solved by taking into account in the simulations the mass loss from evolved stars through stellar winds, planetary nebulae and supernovae explosions.
Book Synopsis Formation de galaxies elliptiques et structures des amas de galaxies by : Gastão Bierrenbach Lima Neto
Download or read book Formation de galaxies elliptiques et structures des amas de galaxies written by Gastão Bierrenbach Lima Neto and published by . This book was released on 1993 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Origine du champ magnétique en cosmologie et formation des galaxies by : Matej Langer
Download or read book Origine du champ magnétique en cosmologie et formation des galaxies written by Matej Langer and published by . This book was released on 2002 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis FORMATION DE GALAXIES ELLIPTIQUES ET STRUCTURE DES AMAS DE GALAXIES by : GASTAO.. BIERRENBACH LIMA-NETO
Download or read book FORMATION DE GALAXIES ELLIPTIQUES ET STRUCTURE DES AMAS DE GALAXIES written by GASTAO.. BIERRENBACH LIMA-NETO and published by . This book was released on 1993 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: LE THEME DE CETTE THESE EST L'ETUDE DE LA FORMATION ET DE LA STRUCTURE DE GALAXIES ELLIPTIQUES AU SEIN DE GROUPES ET AMAS DE GALAXIES. CETTE ETUDE SE DIVISE SELON DEUX APPROCHES PRINCIPALES: L'ANALYSE DES PROPRIETES PHYSIQUES ET MORPHOLOGIQUES DE DEUX AMAS DE GALAXIES, ABELL 85 ET 2199 ; ET L'ETUDE NUMERIQUE DE LA FORMATION DE GALAXIES ELLIPTIQUES PAR COALESCENCE DE GALAXIES SPIRALES. LES AMAS DE GALAXIES ONT ETE ANALYSES A PARTIR DE CLICHES PRIS PAR LE DETECTEUR IPC A BORD DU SATELLITE EINSTEIN DANS LE DOMAINE DE RAYONNEMENT X. LE GAZ INTRA-AMAS RESPONSABLE DE L'EMISSION X EST SUPPOSE ETRE EN EQUILIBRE AVEC LE POTENTIEL DE L'AMAS ET SERT DE TRACEUR DE CE DERNIER. EN UTILISANT UNE TECHNIQUE D'AJUSTEMENT DES CLICHES PAR DES IMAGES DE SYNTHESE, IL EST POSSIBLE DE DETERMINER LE PROFIL RADIAL DE DENSITE DU GAZ EMETTEUR AINSI QUE SA MORPHOLOGIE ET LA PRESENCE DES SOUS-STRUCTURES. EN TIRANT PROFIT DES PROPRIETES SPECTRALES DU DETECTEUR, LE PROFIL DE TEMPERATURE DU GAZ EST ESTIME. L'ETUDE DE LA FORMATION DE GALAXIES ELLIPTIQUES SE FAIT PAR LE BIAIS DE SIMULATIONS A N-CORPS, EN UTILISANT UN CODE EN ARBRE ET UN CODE DE SOMME DIRECTE SUR UN ORDINATEUR MASSIVEMENT PARALLELE. TROIS CLASSES DE CONDITIONS INITIALES ONT ETE REALISEES: DEUX GALAXIES SPIRALES DE MASSE SEMBLABLE PLACEES SOIT EN ORBITE CIRCULAIRE, SOIT SUR UNE TRAJECTOIRE DE COLLISION DE PLEIN FOUET ; DES GROUPES DE GALAXIES SPIRALES EN EQUILIBRE DU VIRIEL ; UN EFFONDREMENT SANS COLLISION D'UN GAZ FROID. LES GALAXIES SPIRALES SUIVENT LE MODELE DE MIYAMOTO & NAGAI A TROIS COMPOSANTES BULBE, DISQUE ET HALO. LES SIMULATIONS ONT ETE SUIVIES JUSQU'A LA FORMATION D'UN OBJET ELLIPTIQUE CENTRAL EN EQUILIBRE QUASI-STATIONNAIRE. LES PROPRIETES PHYSIQUES ET MORPHOLOGIQUES DE L'OBJET FINAL DES SIMULATIONS SONT CONFRONTEES A DES MODELES ISSUS DE LA PHYSIQUE STATISTIQUE APPLIQUEE A DES SYSTEMES GRAVITATIONNELS EN EQUILIBRE. LES STRUCTURES FINES, VARIATION DE L'ELLIPTICITE, DEFORMATION ET ROTATION DES ISOCONTOURS, ONT ETE COMPAREES A DES DONNEES OBSERVATIONNELLES. UNE MODIFICATION DE LA MECANIQUE NEWTONIENNE A ETE AUSSI CONSIDEREE DANS LE CADRE DE L'ETUDE DE LA STRUCTURE DU GAZ INTRA-AMAS
Book Synopsis Formation Des Galaxies by : Benjamin L'Huillier
Download or read book Formation Des Galaxies written by Benjamin L'Huillier and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Formation D'étoiles Et D'amas Stellaires Dans Les Collisions de Galaxies by : Pierre-Emmanuel Belles
Download or read book Formation D'étoiles Et D'amas Stellaires Dans Les Collisions de Galaxies written by Pierre-Emmanuel Belles and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mergers are known to be essential in the formation of large-scale structures and to have a significant role in the history of galaxy formation and evolution. Besides a morphological transformation, mergers induce important bursts of star formation. These starburst are characterised by high Star Formation Efficiencies (SFEs) and Specific Star Formation Rates, i.e., high Star Formation Rates (SFR) per unit of gas mass and high SFR per unit of stellar mass, respectively, compared to spiral galaxies. At all redshifts, starburst galaxies are outliers of the sequence of star-forming galaxies defined by spiral galaxies. We have investigated the origin of the starburst-mode of star formation, in three local interacting systems: Arp 245, Arp 105 and NGC 7252. We combined high-resolution JVLA observations of the 21-cm line, tracing the HI diffuse gas, with UV GALEX observations, tracing the young star-forming regions. We probe the local physical conditions of the Inter-Stellar Medium (ISM) for independent star-forming regions and explore the atomic-to-dense gas transformation in different environments. The SFR/HI ratio is found to be much higher in central regions, compared to outer regions, showing a higher dense gas fraction (or lower HI gas fraction) in these regions. In the outer regions of the systems, i.e., the tidal tails, where the gas phase is mostly atomic, we find SFR/HI ratios higher than in standard HI-dominated environments, i.e., outer discs of spiral galaxies and dwarf galaxies. Thus, our analysis reveals that the outer regions of mergers are characterised by high SFEs, compared to the standard mode of star formation. The observation of high dense gas fractions in interacting systems is consistent with the predictions of numerical simulations; it results from the increase of the gas turbulence during a merger. The merger is likely to affect the star-forming properties of the system at all spatial scales, from large scales, with a globally enhanced turbulence, to small scales, with possible modifications of the initial mass function. From a high-resolution numerical simulation of the major merger of two spiral galaxies, we analyse the effects of the galaxy interaction on the star forming properties of the ISM at the scale of star clusters. The increase of the gas turbulence is likely able to explain the formation of Super Star Clusters in the system. Our investigation of the SFR-HI relation in galaxy mergers will be complemented by high-resolution HI data for additional systems, and pushed to yet smaller spatial scales.
Download or read book Origines written by Xuan Thuan Trinh and published by Gallimard Education. This book was released on 2006-01 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: Retrace l'histoire de l'univers et de la vie en présentant le big bang, la formation du système solaire, ainsi que l'origine des galaxies, des étoiles, des planètes, de la vie, de l'espèce humaine et de la conscience.
Download or read book Mercury written by and published by . This book was released on 2000 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mercury gives informed perspectives on salient issues in research, education, history, and public policy relating to astronomy.
Book Synopsis Galaxies and Cosmology by : Francoise COMBES
Download or read book Galaxies and Cosmology written by Francoise COMBES and published by Springer Science & Business Media. This book was released on 2004-08-11 with total page 468 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unique in its breadth of coverage and level of presentation, this revised textbook provides more on the nature of galaxies, extragalactic objects, the large-scale structure of the Universe, and cosmology than is available in general textbooks on astronomy. It remains, however, accessible to advanced undergraduate students. One or more chapters are devoted to each of the following: the classification and morphology of galaxies; the galactic interstellar medium; galactic kinematics; elliptical, spiral, and barred spiral galaxies; the interactions between galaxies; extragalactic radio sources, quasars and their line spectra, and other active galactic nuclei; the formation of galaxies; the Universe as a whole; and cosmology.
