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19 Result(s)

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  1. No Access

    Chapter and Conference Paper

    Chaos in Galaxies

    D. Pfenniger in Chaos in Astronomy (2009)

  2. No Access

    Article

    Equation of state and stability of the helium-hydrogen mixture at cryogenic temperature

    The equation of state and the stability of the helium-molecular hydrogen mixture at cryogenic temperature up to moderate pressure are studied by means of current molecular physics methods and statistical mecha...

    Y. Safa, D. Pfenniger in The European Physical Journal B (2008)

  3. No Access

    Chapter and Conference Paper

    Condensed Phases of H2 in the ISM

    Below a temperature of 33K molecular hydrogen can condense to liquid, and below 14 K to solid phase. These phase transitions require however a vapor pressure large enough that can be satisfied in the ISM only ...

    D. Pfenniger in The Dense Interstellar Medium in Galaxies (2004)

  4. No Access

    Article

    Sub-kpc stellar kinematics of AGN as revealed by ISAAC (VLT/ANTU) spectroscopy

    D. Greusard, E. Emsellem, F. Combes, D. Friedli… in Astrophysics and Space Science (2001)

  5. No Access

    Article

    Scaling Laws in Self-Gravitating Discs

    The interstellar medium (ISM) reveals strongly inhomogeneous structures on every scale. These structures do not seem completely random since they obey certain power laws. Larson's (1981)) law σ∝ Rδ and the plausi...

    D. Huber, D. Pfenniger in Astrophysics and Space Science (2001)

  6. No Access

    Article

    Formation of Massive Counter-Rotating Discs: An Alternative Scenario

    I. Puerari, D. Pfenniger in Astrophysics and Space Science (2001)

  7. No Access

    Chapter

    Sub-KPC Stellar Kinematics of AGN as Revealed by Isaac (VLT/ANTU) Spectroscopy

    This study is part of the ‘Dynamics of Embedded Bars and Connections with AGN’ (DEBCA) project whose main goal is to provide new insights on the fueling processes of AGN. For that purpose the DEBCA team plans to ...

    D. Greusard, E. Emsellem, F. Combes, D. Friedli, D. Pfenniger… in The Evolution of Galaxies (2001)

  8. No Access

    Article

    Distribution of Kolmogorov-Sinaï Entropy in Self-Consistent Models of Barred Galaxies

    The properties of chaos in 2D self-consistent models of barred galaxies are investigated using Kolmogorov-Sinai entropy hKS. These models are constructed with Schwarzschild's method which combines orbits as eleme...

    H. Wozniak, D. Pfenniger in Celestial Mechanics and Dynamical Astronomy (1999)

  9. No Access

    Chapter and Conference Paper

    Making Spirals with Counter-Rotating Disks

    A single merger scenario for making galaxies such as NGC 4550 possessing equal coplanar counter-rotating stellar disks is investigated by collisionless N-body technique. The scenario is successful in producing...

    D. Pfenniger in Galaxy Interactions at Low and High Redshift (1999)

  10. No Access

    Chapter and Conference Paper

    Distribution of Kolmogorov-Sinaï Entropy in Self-Consistent Models of Barred Galaxies

    The properties of chaos in 2D self-consistent models of barred galaxies are investigated using Kolmogorov-Sinai entropy h KS. These models are constructed with Schwarzschild’s method which combines ...

    H. Wozniak, D. Pfenniger in Impact of Modern Dynamics in Astronomy (1999)

  11. No Access

    Chapter

    3D N-Body Simulations of the Milky Way

    While the existence of a central bar in our Galaxy now seems to be well established, its parameters (such as position angle, extension, axis ratio, angular speed etc...) still remain controversial. The large a...

    R. Fux, L. Martinet, D. Pfenniger in Unsolved Problems of the Milky Way (1996)

  12. No Access

    Chapter and Conference Paper

    Fundamental Aspects of the ISM Fractality

    The ubiquitous clumpy state of the ISM raises a fundamental and open problem of physics, which is the correct statistical treatment of systems dominated by long range interactions. A simple solvable hierarchic...

    D. Pfenniger in New Extragalactic Perspectives in the New South Africa (1996)

  13. No Access

    Chapter and Conference Paper

    Very Cold Gas and Dark Matter

    We have recently proposed a new candidate for baryonic dark matter: very cold molecular gas, in near-isothermal equilibrium with the cosmic background radiation at 2.73 K. The cold gas, of quasi-primordial abu...

    F. Combes, D. Pfenniger in New Extragalactic Perspectives in the New South Africa (1996)

  14. No Access

    Chapter and Conference Paper

    Galactic Dynamics and Dark Matter with Sub-Milliarcsecond Astrometry

    Improving the astrometric accuracy by one or two orders of magnitude over ground-based techniques will not only change our raw knowledge about the Galaxy, but it will also modify 1) the fundamental questions t...

    D. Pfenniger in Astronomical and Astrophysical Objectives … (1995)

  15. No Access

    Book and Conference Proceedings

    Ergodic Concepts in Stellar Dynamics

    Proceedings of an International Workshop Held at Geneva Observatory University of Geneva, Switzerland, 1–3 March 1993

    V. G. Gurzadyan, D. Pfenniger in Lecture Notes in Physics (1994)

  16. No Access

    Chapter and Conference Paper

    Fourier Analysis of Barred Galaxies: A Convenient Alternative to the Component Decomposition

    In the traditional decomposition approach, a barred galaxy is assumed to be the superimposition of three components, the bulge, the bar, and the disk. The bulge and the disk are assumed to be axisymmetric; sin...

    P. Dubath, B. J. Jarvis, L. Martinet… in Morphological and Physical Classification … (1992)

  17. No Access

    Chapter and Conference Paper

    Slow Dissipation in Bars and the Fuelling of Nuclei

    The problem of multiphase gas flow in the central regions of barred galaxies, and the influence of a central mass on the rate of accretion are considered. In order to study the most essential factors, the comp...

    D. Pfenniger, C. Norman in Dynamics and Interactions of Galaxies (1990)

  18. No Access

    Chapter and Conference Paper

    The velocity fields of barred galaxies

    D. Pfenniger in New Aspects of Galaxy Photometry (1985)

  19. No Access

    Chapter

    Ordered and Semi-Ergodic Motions in Barred Galaxies

    A preliminary step towards the construction of self-consistent models for barred galaxies consists in understanding the stellar orbital behaviour in a given axisymmetrical + bar-like potential and, in particul...

    E. Athanassoula, O. Bienaymé, L. Martinet… in Internal Kinematics and Dynamics of Galaxi… (1983)