6 results on '"Y. Revaz"'
Search Results
2. Photometric survey of binary near-Earth asteroids
- Author
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J. Zhu, Z. Krzeminski, Štefan Gajdoš, Michael D. Hicks, A. Klotz, B. L. Knight, R. R. Dyvig, Peter Brown, M. Grenon, Yu. N. Krugly, Robert D. Stephens, Walter R. Cooney, Y. Revaz, Jozef Vilagi, P. Scheirich, A. Grauer, Raoul Behrend, Franck Marchis, Lenka Šarounová, Peter Kusnirak, Stefano Mottola, Robert J. Whiteley, Gianluca Masi, G. Burki, Alan W. Harris, Ellen S. Howell, V. Cotrez, C. Demeautis, Jean-Luc Margot, Petr Pravec, N. Waelchli, David J. Tholen, Stephen Larson, Donald P. Pray, Vishnu Reddy, L. Brunetto, S. Moore, P. Thierry, D. Matter, Michael C. Nolan, G. Esquerdo, K. Kirsch, G. M. Funkhouser, G. Kober, G. Hahn, W. Holliday, Brian D. Warner, D. R. Degraff, F. P. Velichko, Adrian Galad, David Higgins, M. Rieugné, Lance A. M. Benner, L. Snyder, R. Roy, S. M. Slivan, N. Kaiser, Astronomical Institute of the Czech Academy of Sciences (ASU / CAS), Czech Academy of Sciences [Prague] (CAS), DLR Institute of Planetary Research, Rutherfordstr. 2, D-12489 Berlin, Germany, Department of Physics and Astronomy, University of Western Ontario, Carbuncle Hill Observatory, Palmer Divide Observatory, Colorado Springs, Space Science Institute, La Canada, National Astronomy and Ionosphere Center / Arecibo Observatory, HC3 Box 53995, Arecibo (NAIC), Jet Propulsion Laboratory, California Institute of Technology (JPL), Department of Astronomy, Cornell University, Ithaca, NY 14853, USA, Modra Observatory, Department of Astronomy, Physics of the Earth and Meteorology, River Oaks Observatory, 1125 Isaac Creek Circle, New Braunfels, TX 78132, USA, Institute of Astronomy [Kharkiv], V.N. Karazin Kharkiv National University (KhNU), Institute for Astronomy, University of Hawaii, Lunar and Planetary Laboratory [University of Arizona] (LPL), University of Arizona, Department of Astronomy, University of California, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Groupe Astrométrie et Planétologie (GAP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Alfred University, Department of Physics and Astronomy, University of Arkansas, United States Naval Observatory (USNO), Beijing Astronomical Observatory, Chinese Academy of Sciences, Badlands Observatory, Keck Observatoires, University of North Dakota, Astronomy Department, California Institute of Technology, Pasadena, Università degli Studi di Roma Tor Vergata [Roma], Campo Catino Observatory, Hunters Hill Observatory, Department of Astronomy, Whitin Observatory, Wellesley College, Observatoire de Genève, Observatoire de Blauvac, 138 Village-Neuf, F.-X. Bagnoud Observatory, CH-3961 St-Luc, Switzerland, Observatoire d'astronomie de Saint-Caprais, Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Le Cres Observatory, and Observatoire N°139 d'Antibes
- Subjects
Physics ,Angular momentum ,education.field_of_study ,Near-Earth object ,photometry ,Population ,binary ,Astronomy ,Astronomy and Astrophysics ,Asteroids ,Space and Planetary Science ,Asteroid ,Total angular momentum quantum number ,Roche limit ,Orbital motion ,Terrestrial planet ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,education - Abstract
Photometric data on 17 binary near-Earth asteroids (15 of them are certain detections, two are probables) were analysed and characteristic properties of the near-Earth asteroid (NEA) binary population were inferred. We have found that binary systems with a secondary-to-primary mean diameter ratio D s / D p ⩾ 0.18 concentrate among NEAs smaller than 2 km in diameter; the abundance of such binaries decreases significantly among larger NEAs. Secondaries show an upper size limit of D s = 0.5 – 1 km . Systems with D s / D p ⩽ 0.5 are abundant but larger satellites are significantly less common. Primaries have spheroidal shapes and they rotate rapidly, with periods concentrating between 2.2 to 2.8 h and with a tail of the distribution up to ∼4 h. The fast rotators are close to the critical spin for rubble piles with bulk densities about 2 g/cm3. Orbital periods show an apparent cut-off at P orb ∼ 11 h ; closer systems with shorter orbital periods have not been discovered, which is consistent with the Roche limit for strengthless bodies. Secondaries are more elongated on average than primaries. Most, but not all, of their rotations appear to be synchronized with the orbital motion; nonsynchronous secondary rotations may occur especially among wider systems with P orb > 20 h. The specific total angular momentum of most of the binary systems is similar to within ±20% and close to the angular momentum of a sphere with the same total mass and density, rotating at the disruption limit; this suggests that the binaries were created by mechanism(s) related to rotation near the critical limit and that they neither gained nor lost significant amounts of angular momentum during or since formation. A comparison with six small asynchronous binaries detected in the main belt of asteroids suggests that the population extends beyond the region of terrestrial planets, but with characteristics shifted to larger sizes and longer periods. The estimated mean proportion of binaries with D s / D p ⩾ 0.18 among NEAs larger than 0.3 km is 15 ± 4 % . Among fastest rotating NEAs larger than 0.3 km with periods between 2.2 and 2.8 h, the mean proportion of such binaries is (66+10−12)%.
- Published
- 2006
3. Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution
- Author
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J. Hanuš, J. Ďurech, M. Brož, A. Marciniak, B. D. Warner, F. Pilcher, R. Stephens, R. Behrend, B. Carry, D. Čapek, P. Antonini, M. Audejean, K. Augustesen, E. Barbotin, P. Baudouin, A. Bayol, L. Bernasconi, W. Borczyk, J.-G. Bosch, E. Brochard, L. Brunetto, S. Casulli, A. Cazenave, S. Charbonnel, B. Christophe, F. Colas, J. Coloma, M. Conjat, W. Cooney, H. Correira, V. Cotrez, A. Coupier, R. Crippa, M. Cristofanelli, Ch. Dalmas, C. Danavaro, C. Demeautis, T. Droege, R. Durkee, N. Esseiva, M. Esteban, M. Fagas, G. Farroni, M. Fauvaud, S. Fauvaud, F. Del Freo, L. Garcia, S. Geier, C. Godon, K. Grangeon, H. Hamanowa, N. Heck, S. Hellmich, D. Higgins, R. Hirsch, M. Husarik, T. Itkonen, O. Jade, K. Kamiński, P. Kankiewicz, A. Klotz, R. A. Koff, A. Kryszczyńska, T. Kwiatkowski, A. Laffont, A. Leroy, J. Lecacheux, Y. Leonie, C. Leyrat, F. Manzini, A. Martin, G. Masi, D. Matter, J. Michałowski, M. J. Michałowski, T. Michałowski, J. Michelet, R. Michelsen, E. Morelle, S. Mottola, R. Naves, J. Nomen, J. Oey, W. Ogłoza, A. Oksanen, D. Oszkiewicz, P. Pääkkönen, M. Paiella, H. Pallares, J. Paulo, M. Pavic, B. Payet, M. Polińska, D. Polishook, R. Poncy, Y. Revaz, C. Rinner, M. Rocca, A. Roche, D. Romeuf, R. Roy, H. Saguin, P. A. Salom, S. Sanchez, G. Santacana, T. Santana-Ros, J.-P. Sareyan, K. Sobkowiak, S. Sposetti, D. Starkey, R. Stoss, J. Strajnic, J.-P. Teng, B. Trégon, A. Vagnozzi, F. P. Velichko, N. Waelchli, K. Wagrez, H. Wücher, Astronomical Institute of Charles University, Charles University [Prague] (CU), Astronomical Observatory [Poznan], Adam Mickiewicz University in Poznań (UAM), Palmer Divide Observatory, Organ Mesa Observatory, Goat Mountain Astronomical Research Station, Geneva Observatory, Université de Genève = University of Geneva (UNIGE), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Astronomical Institute of the Czech Academy of Sciences (ASU / CAS), Czech Academy of Sciences [Prague] (CAS), Observatoire de Bédoin, Observatoire de Chinon, Courbes de rotation d'astéroïdes, de comètes et d'étoiles variables (CdR & CdL group), CdR & CdL group, Association T60, Observatoire Midi-Pyrénées, Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Harfleur Observatory, Observatoire des Engarouines, Collonges Observatory, Chercheur indépendant, Observatoire N°139 d'Antibes, Osservatorio Colleverde di Guidonia, Observatoire de Saint-Sulpice N°947, DPHY, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Observatorio de San Gervasi, Observatoire de Cabris, Blackberry Observatory, Centre d'Astronomie de Saint-Michel l'Observatoire, Observatoire de Sainte-Hélène, Observatorio Astronómico de Tradate, 138 Village-Neuf, The Amateur Sky Survey (TASS), The Amateur Sky Survey, Shed of Science Observatory, Association AstroQueyras, Association des Utilisateurs de Détecteurs Electroniques (AUDE), Association des Utilisateurs de Détecteurs Electroniques, Observatoire du Bois de Bardon, Dark Cosmology Centre (DARK), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Nordic Optical Telescope (NOT), Instituto de Astrofisica de Canarias (IAC), Hamanowa Astronomical Observatory, DLR Institute of Planetary Research, German Aerospace Center (DLR), Hunters Hill Observatory, Skalnaté Pleso Observatory, A83 Jakokoski Observatory, Institute of Physics [Kielce], Jan Kochanowski University, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Antelope Hills Observatory, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Stazione Astronomica di Sozzago, Forte Software, Scottish Universities Physics Alliance, Institute for Astronomy (SUPA), University of Edinburgh, Club d'Astronomie Lyon Ampéré [Vaulx-en-Velin] (CALA), Nyrölä Observatory (NYTT), Observatorio Montcabre, Observatorio Astronómico de Mallorca (OAM), Observatorio Astronómico de Mallorca, Kingsgrove Observatory, Mt. Suhora Observatory, Pedagogical University, Astronomy Department, Department of Physics [Helsinki], Falculty of Science [Helsinki], Helsingin yliopisto = Helsingfors universitet = University of Helsinki-Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), François-Xavier Bagnoud Observatory, Blauvac Obsevatory, Blauvac Observatory, Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Gnosca Observatory, DeKalb Observatory, Observatoire astronomique des Makes, Laboratoire Kastler Brossel (LKB (Lhomond)), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Institute of Astronomy [Kharkiv], V.N. Karazin Kharkiv National University (KhNU), University of Geneva [Switzerland], European Space Agency (ESA), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), University of Helsinki-University of Helsinki, Université Pierre et Marie Curie - Paris 6 (UPMC)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
010504 meteorology & atmospheric sciences ,photometry ,[PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,media_common.quotation_subject ,Population ,[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP] ,FOS: Physical sciences ,Inverse transform sampling ,Astrophysics ,01 natural sciences ,Photometry (optics) ,models ,Observatory ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,education ,010303 astronomy & astrophysics ,Scaling ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,media_common ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,education.field_of_study ,Physical model ,Minor planets ,Astronomy and Astrophysics ,Asteroids: general ,13. Climate action ,Space and Planetary Science ,Sky ,Asteroid ,Physics::Space Physics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. We used classical dense photometric lightcurves from several sources and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetics and observed pole-latitude distributions, we were able to constrain the typical values of the cYORP parameter as between 0.05 and 0.6., Accepted for publication in A&A, January 15, 2013
- Published
- 2013
4. Stellar metallicity gradients of Local Group dwarf galaxies
- Author
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S. Taibi, G. Battaglia, R. Leaman, A. Brooks, C. Riggs, F. Munshi, Y. Revaz, and P. Jablonka
- Subjects
star-formation history ,globular-cluster ,polar ring galaxy ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,galaxies: dwarf ,satellite galaxies ,Astrophysics - Astrophysics of Galaxies ,local group ,ngc 147 ,ca ii triplet ,population gradients ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Astrophysics::Solar and Stellar Astrophysics ,galaxies: abundances ,Astrophysics::Earth and Planetary Astrophysics ,spheroidal galaxy ,chemical evolution ,Astrophysics::Galaxy Astrophysics ,techniques: spectroscopic ,spectroscopic survey - Abstract
Through a homogeneous analysis of spectroscopic literature data of red giant stars, we determine the radial metallicity profiles of 30 dwarf galaxies in the Local Group. We explore correlations between the calculated metallicity gradients and stellar mass, star formation history and environment, delivering the largest compilation to date of this type. The dwarf galaxies in our sample mostly show metallicity profiles decreasing with radius, with some exhibiting rather steep profiles. The derived metallicity gradients as a function of the half-light radius, $\nabla_{\rm [Fe/H]} (R/R_e)$, show no statistical differences when compared with the galaxies' morphological type, nor with their distance from the Milky Way or M31. No correlations are found with either stellar mass or star formation timescales. In particular, we do not find the linear relationship between $\nabla_{\rm [Fe/H]} (R/R_e)$ and the galaxies' median age $t_{50}$, as instead shown in the literature for a set of simulated systems. The presence of high angular momentum in some of our galaxies does not seem to have an impact on the gradient values. The strongest gradients in our sample are observed in systems that are likely to have experienced a past merger event. By excluding them, the analysed dwarf galaxies show mild gradients ($\sim -0.1$ dex $R_e^{-1}$) with little scatter between them, regardless of their stellar mass, dynamical state, and star formation history. These results are in good agreement with different sets of simulations presented in the literature and analysed using the same method as for the observed sample. The interplay between the multitude of factors that could drive the formation of metallicity gradients in dwarf galaxies likely combine in complex ways to produce in general comparable values., 27 pages, 9 figures, 2 tables (additional 10 figures and 2 tables in the appendix). Accepted for publication in A&A
5. A population of compact elliptical galaxies detected with the Virtual Observatory.
- Author
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Chilingarian I, Cayatte V, Revaz Y, Dodonov S, Durand D, Durret F, Micol A, and Slezak E
- Abstract
Compact elliptical galaxies are characterized by small sizes and high stellar densities. They are thought to form through tidal stripping of massive progenitors. However, only a handful of them were known, preventing us from understanding the role played by this mechanism in galaxy evolution. We present a population of 21 compact elliptical galaxies gathered with the Virtual Observatory. Follow-up spectroscopy and data mining, using high-resolution images and large databases, show that all the galaxies exhibit old metal-rich stellar populations different from those of dwarf elliptical galaxies of similar masses but similar to those of more massive early-type galaxies, supporting the tidal stripping scenario. Their internal properties are reproduced by numerical simulations, which result in compact, dynamically hot remnants resembling the galaxies in our sample.
- Published
- 2009
- Full Text
- View/download PDF
6. The basic dynamical mechanism in spiral galaxies.
- Author
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Pfenniger D and Revaz Y
- Abstract
This paper explicates the most fundamental mechanism that rules spiral galaxies. Although spiral galaxies are complex systems for which we do not yet have a complete understanding, the dark matter being the most severe unknown, it is possible to pinpoint the few physical factors that determine their most important properties, such as bars and spiral arms. Dynamics linked to the dissipative nature of gas and its transformation into stars provides clues that spiral galaxies are driven by dissipation close to a state of marginal stability with respect to the dynamics in the galaxy plane. Here, we present numerical evidence suggesting that warps play a similar role but in the transverse direction. N-body simulations show that typical galactic disks are also marginally stable with respect to a bending instability, leading to typical observed warps. The frequent occurrence of warps and asymmetries in the outer galactic disks, like bars in the inner disks, give new constraints on the dark matter, but this time in the outer disks.
- Published
- 2005
- Full Text
- View/download PDF
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