Helioseismology, Asteroseismology, and MHD Connections

ISBN-13: 9780387894812 / Angielski / Twarda / 2009 / 638 str.

Laurent Gizon; Paul S. Cally; J. Leibacher

Opis

Laurent Gizon.Paul Cally.John Leibacher Originally published in the journal Solar Physics, Volume 251, Nos 1-2, 1-2. DOI: 10. 1007/s11207-008-9248-y (c) The Author(s) 2008 The seismology of the Sun and stars has come a long way in a short time. The "original" Global Helioseismology has reached a level of maturity that allows many internal prop- ties of the Sun to be probed with exquisite precision, although it currently faces a severe challenge to reconcile interior models with helioseismic inversions near the base of the c- vection zone in the age of the new solar chemical abundances. Asteroseismology suffers in comparisonbybeingrestrictedtoverylowsphericalharmonicdegree( ), butitmakesupfor this by providing many more subjects for study (including solar-like stars) and many cases of well-identi ed g modes. Where once we were restricted to stellar spectra in studying in- vidual stars, asteroseismology now provides a crucial tool with which we may explore their deep structure. Its natural synergy with planet-search programs also invigorates it. Local Helioseismology has seen the development of an exciting array of techniques and insights over the two decades since observations of surface oscillations in and around active regions gave the rst clues that something different was happening there, and it has been parti- larly important in mapping ows of various types in shallow subsurface layer

Spis treści

The Current Status of Asteroseismology.- The Solar-Stellar Connection: Magneto-Acoustic Pulsations in 1.5M ? – 2M ? Peculiar A Stars.- Fourier Analysis of Gapped Time Series: Improved Estimates of Solar and Stellar Oscillation Parameters.- Perspectives in Global Helioseismology and the Road Ahead.- Meridional Circulation and Global Solar Oscillations.- Global Effects of Local Sound-Speed Perturbations in the Sun: A Theoretical Study.- Angular Momentum Transport in the Sun’s Radiative Zone by Gravito-Inertial Waves.- Influence of Low-Degree High-Order p-Mode Splittings on the Solar Rotation Profile.- Can We Constrain Solar Interior Physics by Studying the Gravity-Mode Asymptotic Signature?.- Zonal Velocity Bands and the Solar Activity Cycle.- Acoustic Radius Measurements from MDI and GONG.- Spatio-Temporal Analysis of Photospheric Turbulent Velocity Fields Using the Proper Orthogonal Decomposition.- Calculation of Spectral Darkening and Visibility Functions for Solar Oscillations.- Uncovering the Bias in Low-Degree p-Mode Linewidth Fitting.- Analysis of MDI High-Degree Mode Frequencies and their Rotational Splittings.- Recent Developments in Local Helioseismology.- Observation and Modeling of the Solar-Cycle Variation of the Meridional Flow.- Three-Dimensional MHD Wave Propagation and Conversion to Alfvén Waves near the Solar Surface. I. Direct Numerical Solution.- Surface-Focused Seismic Holography of Sunspots: I. Observations.- Helioseismology of Sunspots: Confronting Observations with Three-Dimensional MHD Simulations of Wave Propagation.- Time?–?Distance Modelling in a Simulated Sunspot Atmosphere.- Modelling the Coupling Role of Magnetic Fields in Helioseismology.- Physical Properties of Wave Motion in Inclined Magnetic Fields within Sunspot Penumbrae.- On Absorption and Scattering of P Modes by Small-Scale Magnetic Elements.- Time?–?Distance Analysis of the Emerging Active Region NOAA 10790.- High-Resolution Mapping of Flows in the Solar Interior: Fully Consistent OLA Inversion of Helioseismic Travel Times.- Structure and Evolution of Supergranulation from Local Helioseismology.- Probing the Subsurface Structures of Active Regions with Ring-Diagram Analysis.- Effects of Random Flows on the Solar f Mode: I. Horizontal Flow.- Effects of Random Flows on the Solar f Mode: II. Horizontal and Vertical Flow.- Instrumental Response Function for Filtergraph Instruments.- Seismology of a Sunspot Atmosphere.- Enhanced p-Mode Absorption Seen Near the Sunspot Umbral?–?Penumbral Boundary.- Global Acoustic Resonance in a Stratified Solar Atmosphere.- DOT Tomography of the Solar Atmosphere VII. Chromospheric Response to Acoustic Events.- Velocity and Intensity Power and Cross Spectra in Numerical Simulations of Solar Convection.- 3D MHD Coronal Oscillations about a Magnetic Null Point: Application of WKB Theory.- Nonlinear Numerical Simulations of Magneto-Acoustic Wave Propagation in Small-Scale Flux Tubes.- Seismic Emissions from a Highly Impulsive M6.7 Solar Flare.- Mechanics of Seismic Emission from Solar Flares.

Blurb

This volume presents a timely snapshot of the state of helio- and asteroseismology in the era when the SOHO/MDI instrument is about to be replaced by SDO/HMI and the CoRoT space mission is yielding its first long-duration light curves of thousands of stars. The articles and topics in this book are inspired by two seminal conferences, HELAS II and SOHO19/GONG 2007, but contributions from other experts have been commissioned as well. For example, three key papers were invited to describe the current status of asteroseismology, global helioseismology, and local helioseismology. These papers provide a framework for the other contributions and together they form a complete description of our understanding of pressure waves in the Sun and other stars.

This volume is aimed at solar physicists and astronomers specializing in helio- and asteroseismology.