Tuesday, 17 November
Disk-outflow coupling: Energetics around spinning black holes
http://www.arxiv.org/abs/0911.3049Debbijoy Bhattacharya, Shubhrangshu Ghosh, Banibrata Mukhopadhyay
26 pages including 7 figures; submitted in ApJ
The mechanism by which outflows and plausible jets are driven from black hole systems, still remains observationally elusive.
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17 11 09 - 17:34 |
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Acceleration and collimation of relativistic MHD disk winds
http://www.arxiv.org/abs/0911.3001O. Porth, C. Fendt
submitted to ApJ
We perform axisymmetric relativistic magnetohydrodynamic (MHD) simulations to investigate the acceleration and collimation of jets and outflows from disks around compact objects.
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17 11 09 - 17:33 |
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Thermal instability in ionized plasma
http://www.arxiv.org/abs/0911.2986Mohsen Shadmehri, Mohsen Nejad-Asghar, Alireza Khesali
Accepted for publication in Astrophysics & Space Science
We study magnetothermal instability in the ionized plasmas including the effects of Ohmic, ambipolar and Hall diffusion. Magnetic field in the single fluid approximation does not allow transverse thermal condensations, however, non-ideal effects highly diminish the stabilizing role of the magnetic field in thermally unstable plasmas. Therefore, enhanced growth rate of thermal condensation modes in the presence of the diffusion mechanisms speed up the rate of structure formation.
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17 11 09 - 17:31 |
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Towards a MHD theory of SASI: toy model of the advective-acoustic cycle in a magnetized flow
http://www.arxiv.org/abs/0911.2795Jerome Guilet, Thierry Foglizzo
13 pages, 9 figures, submitted to ApJ
The effect of a magnetic field on the linear phase of the advective-acoustic instability is investigated, as a first step toward a MHD theory of the Stationary Accretion Shock Instability taking place during stellar core collapse.
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17 11 09 - 17:29 |
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Oscillations and instabilities of fast and differentially rotating relativistic stars
http://www.arxiv.org/abs/0911.2764Christian Krüger, Erich Gaertig, Kostas D. Kokkotas
15 pages, 9 figures
We study non-axisymmetric oscillations of rapidly and differentially rotating relativistic stars in the Cowling approximation.
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17 11 09 - 17:27 |
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An association between anisotropic plasma heating and instabilities in the solar wind
http://www.arxiv.org/abs/0911.2715J. C. Kasper, B. A. Maruca, S. D. Bale
four pages, four figures, submitted to PRL
We present an analysis of the components of solar wind proton temperature perpendicular and parallel to the local magnetic field as a function of proximity to plasma instability thresholds.
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17 11 09 - 17:26 |
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Monday, 16 November
A turbulence model for smoothed particle hydrodynamics
http://www.arxiv.org/abs/0911.2523J. J. Monaghan
34 pages, 11 figures
The aim of this paper is to devise a turbulence model for the particle method Smoothed Particle Hydrodynamics (SPH) which makes few assumptions, conserves linear and angular momentum, satisfies a discrete version of Kelvin's circulation theorem, and is computationally efficient.
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16 11 09 - 13:17 |
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Sunday, 15 November
Turbulence modeling and the physics of the intra-cluster medium
http://www.arxiv.org/abs/0911.2629L. Iapichino (1), A. Maier (2), W. Schmidt (3), J. C. Niemeyer (3) ((1) ZAH/ITA, Univ. Heidelberg; (2) Lehrstuhl für Astronomie, Univ. Würzburg; (3) Institut für Astrophysik, Univ. Göttingen)
To appear in the proceedings of the "Invisible Universe International Conference"
FEARLESS (Fluid mEchanics with Adaptively Refined Large Eddy SimulationS) is a new numerical scheme arising from the combined use of subgrid scale (SGS) model for turbulence at the unresolved length scales and adaptive mesh refinement (AMR) for resolving the large scales.
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15 11 09 - 21:14 |
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Magnetohydrodynamic turbulence in a strongly magnetised plasma
http://www.arxiv.org/abs/0911.2581S. Sridhar (RRI, India)
invited review, submitted to Astronomische Nachrichten
I present a review of incompressible magnetohydrodynamic (MHD) turbulence in a strongly magnetised plasma.
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15 11 09 - 21:13 |
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Detecting the orientation of magnetic fields in galaxy clusters
http://www.arxiv.org/abs/0911.2476Christoph Pfrommer (1), L. Jonathan Dursi (2, 1), ((1) CITA, (2) SciNet)
this http URL
Clusters of galaxies, filled with hot, magnetised plasma, are the largest bound objects in existence and an important touchstone in understanding the formation of structures in our Universe.
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15 11 09 - 21:00 |
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Interactions between a massive planet and a disc
http://www.arxiv.org/abs/0911.2468Pau Amaro-Seoane, Ignasi Ribas, Ulf Loeckmann, Holger Baumgardt
Two-page contribution to "Pathways towards habitable planets". An extended version of this note will be soon published in ApJ (needs asp2006.sty, psfig.sty and picins.sty, included)
We analyse the potential migration of massive planets forming far away from an inner planetary system.
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15 11 09 - 20:59 |
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Friday, 13 November
Self-consistent Simulations of Plasma-Neutral in a Partially Ionized Astrophysical Turbulent Plasma
http://www.arxiv.org/abs/0911.2192Dastgeer Shaikh, G. P. Zank
To appear in the Proceedings of Solar Wind 12
A local turbulence model is developed to study energy cascades in the heliosheath and outer heliosphere (OH) based on self-consistent two-dimensional fluid simulations.
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13 11 09 - 20:06 |
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Destabilizing Taylor-Couette flow with suction
http://www.arxiv.org/abs/0911.2403Basile Gallet, Charles R. Doering, Edward A. Spiegel
33 pages, 9 figures
We consider the effect of radial fluid injection and suction on Taylor-Couette flow.
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13 11 09 - 09:06 |
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Thursday, 12 November
Simulations of momentum feedback by black hole winds
http://www.arxiv.org/abs/0911.2434Sergei Nayakshin, Chris Power (Leicester)
17 pages, to appear in MNRAS
The observed super-massive black hole (SMBH) mass -- galaxy velocity dispersion ($M_{\rm bh} - \sigma$) correlation may be established when winds/outflows from the SMBH drive gas out of the potential wells of classical bulges.
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12 11 09 - 22:40 |
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Comparisons and Connections between Mean Field Dynamo Theory and Accretion Disc Theory
http://www.arxiv.org/abs/0911.2315Eric G. Blackman (U. Rochester)
9 pages, to appear in Astron. Nachr., Vol. 331, Issue 1, 2010
The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi-analytic mean field theories that distill the essential physics.
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12 11 09 - 22:39 |
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The structure of thin accretion discs around magnetised stars
http://www.arxiv.org/abs/0911.2084Solomon Belay Tessema, Ulf Torkelsson
9 pages, 10 figures. The paper is accepted for publication in Astronomy & Astrophysics
Aims: We determine the steady-state of an axisymmetric thin accretion disc with an internal dynamo around a magnetised star.
Methods: Starting from the vertically integrated equations of magnetohydrodynamics we derive a single ordinary differential equation for a thin accretion disc around a massive magnetic dipole and integrate this equation numerically from the outside inwards.
Results: Our numerical solution shows that the torque between the star and the accretion disc is dominated by the contribution from the dynamo in the disc.
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12 11 09 - 22:35 |
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Helioseismic detection of deep meridional flow
http://www.arxiv.org/abs/0911.2013Douglas Gough, Bradley W. Hindman
23 pages, 9 color figures, submitted to the Astrophysical Journal
Steady meridional flow makes no first-order perturbation to the frequencies of helioseismic normal modes.
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12 11 09 - 22:34 |
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Gas Accretion from a Circumbinary Disk
http://www.arxiv.org/abs/0911.2032Tomoyuki Hanawa, Yasuhiro Ochi, Koichi Ando
41 pages, 25 PostScript figures, uses AASTeX, to appear in ApJ
A new computational scheme is developed to study gas accretion from a circumbinary disk.
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12 11 09 - 22:33 |
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The physics of strong magnetic fields and activity of magnetars
http://www.arxiv.org/abs/0911.2066Qiu He Peng, Hao Tong
Proceedings of the 10th Symposium on Nuclei in the Cosmos (NIC X). July 27 - August 1, 2008 Mackinac Island, Michigan, USA
A phase transition from paramagnetism to ferromagnetism in neutron star interior is explored.
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12 11 09 - 22:32 |
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Tuesday, 10 November
Solar-Terrestrial Simulations of CMEs with a Realistic Initiation Mechanism: Case Study for Active Region 10069
http://www.arxiv.org/abs/0911.1895N. Lugaz, I. I. Roussev, I. V. Sokolov, C. Jacobs
4 pages, 2 figures, refereed proceedings for Solar Wind 12
Most simulations of coronal mass ejections (CMEs) to date either focus on the interplanetary propagation of a giant plasma "blob" without paying too much attention to its origin and to the formation process or they focus on the complex evolution of the coronal magnetic field due to (sub-)photospheric motions which result in an eruption.
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10 11 09 - 22:20 |
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Exploring the $P_{cyc}$ vs $P_{rot}$ relation with flux transport dynamo models of solar-like stars
http://www.arxiv.org/abs/0911.1947L. Jouve (1,2), B.P. Brown (3), A.S. Brun (1,3)
12 pages, 8 figures, accepted for publication by A&A 1: AIM, CEA/DSM-CNRS-Univ. Paris 7, IRFU/SAp, France, 2: D.A.M.T.P., Centre for Mathematical Sciences, Univ. of Cambridge, UK, 3: JILA and Department of Astrophysical and Planetary Sciences, Univ. of Colorado, USA
Aims: To understand stellar magnetism and to test the validity of the Babcock-Leighton flux transport mean field dynamo models with stellar activity observations Methods: 2-D mean field dynamo models at various rotation rates are computed with the STELEM code to study the sensitivity of the activity cycle period and butterfly diagram to parameter changes and are compared to observational data.
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10 11 09 - 22:20 |
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Revisiting 2D Numerical Models for the 19th century outbursts of $\eta$ Carinae
http://www.arxiv.org/abs/0911.1808R.F. González, A.M. Villa, G.C. Gómez, E.M. de Gouveia Dal Pino, A.C. Raga, J. Cantó, P.F. Velázquez, E. de la Fuente
accepted for publication in MNRAS
We present here new results of two-dimensional hydrodynamical simulations of the eruptive events of the 1840s (the great) and the 1890s (the minor) eruptions suffered by the massive star $\eta$ Car.
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10 11 09 - 22:19 |
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Structure, Kinematics, and Chemical Enrichment Patterns after Major Gas-Rich Disc-Disc Mergers
http://www.arxiv.org/abs/0911.1801Simon Richard, Chris B. Brook, Hugo Martel, Daisuke Kawata, Brad K. Gibson, Patricia Sanchez-Blazquez
17 pages, 20 figures, to be published in MNRAS
We used an N-body smoothed particle hydrodynamics algorithm, with a detailed treatment of star formation, supernovae feedback, and chemical enrichment, to perform eight simulations of mergers between gas-rich disc galaxies.
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10 11 09 - 22:18 |
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Dependence of the Star Formation Efficiency on the Parameters of Molecular Cloud Formation Simulations
http://www.arxiv.org/abs/0911.1795Yetli Rosas-Guevara, Enrique Vazquez-Semadeni, Gilberto C. Gomez, A.-Katharina Jappsen
19 pages, submitted to MNRAS
We investigate the response of the star formation efficiency (SFE) to the main parameters of simulations of molecular cloud formation by the collision of warm diffuse medium (WNM) cylindrical streams, neglecting stellar feedback and magnetic fields.
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10 11 09 - 22:17 |
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Monday, 09 November
Dust Transport in Protostellar Disks Through Turbulence and Settling
http://www.arxiv.org/abs/0911.1533N. J. Turner, A. Carballido, T. Sano
ApJ in press
We apply ionization balance and MHD calculations to investigate whether magnetic activity moderated by recombination on dust can account for the mass accretion rates and the mid-infrared spectra and variability of protostellar disks.
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