Author name code: mihalas-weibel ADS astronomy entries on 2022-09-14 author:Mihalas, Barbara ------------------------------------------------------------------------ Title: How may seismological measurements constrain parameters of stellar structure? Authors: Brown, T. M.; Christensen-Dalsgaard, J.; Mihalas, B. W. Bibcode: 1993ASPC...40..554B Altcode: 1993IAUCo.137..554B; 1993ist..proc..554B No abstract at ADS Title: The Equation of State for Stellar Envelopes. IV. Thermodynamic Quantities and Selected Ionization Fractions for Six Elemental Mixes Authors: Mihalas, Dimitri; Hummer, D. G.; Mihalas, Barbara Weibel; Daeppen, Werner Bibcode: 1990ApJ...350..300M Altcode: The free-energy minimization technique in the form developed in the preceding papers in this series is employed to evaluate thermodynamic quantities and ionization fractions on a fine temperature and density grid for six astrophysical mixtures of 15 elements. The mixtures range from that appropriate to super-metal-rich stars, through solar abundance, to that for extreme Population II objects. In this paper, the results for solar abundances are summarized in a form that is illustrative and which facilitates comparison with the results from other equation of state calculations. Title: The Equation of State for Stellar Envelopes. III. Thermodynamic Quantities Authors: Daeppen, Werner; Mihalas, Dimitri; Hummer, D. G.; Mihalas, Barbara Weibel Bibcode: 1988ApJ...332..261D Altcode: The authors derive general formulae for the computation of the thermodynamic properties of a partially ionized (and/or dissociated) multicomponent gas in terms of second derivatives of the free energy with respect to temperature, volume, and occupation numbers. For the free energy used in previous work the authors give explicit analytical expressions for all derivatives required to construct the thermodynamic quantities. Representative results for several different thermodynamic properties of a hydrogen-helium plasma with N(He)/N(H) = 0.10 are presented as color plots. Title: Book-Review - Foundations of Radiation Hydrodynamics Authors: Michalas, D.; Mihalas, B.; Kampfer, B. Bibcode: 1988AN....309..381M Altcode: No abstract at ADS Title: Book-Review - Foundations of Radiation Hydrodynamics Authors: Mihalas, D.; Mihalas, B. W.; Machado, M. E. Bibcode: 1986SoPh..103..409M Altcode: No abstract at ADS Title: Solar waves and oscillations. Authors: Brown, T. M.; Mihalas, B. W.; Rhodes, E. J., Jr. Bibcode: 1986psun....1..177B Altcode: Contents: Theory of waves and oscillations (basic equations: full hydromagnetic equations, linearized equations; waves: nonmagnetic waves, magnetohydrodynamic waves; general properties of solar oscillations: equations and spheroidal mode solutions, Cowling approximation, asymptotic behavior of p- and g-mode frequencies, radial oscillations, properties of nonadiabatic solutions, toroidal oscillations; excitation and damping of solar pulsations: excitation and damping mechanisms, mode lifetimes, stability of solar pulsation modes; detailed solutions for frequencies and frequency splitting: effects of structure on unperturbed frequencies, effects of rotation, effects of internal magnetic fields; future theoretical needs). Observations (observational techniques: diagnostics of spectrum lines, techniques for observing oscillations and trapped waves; oscillations observed: observations of 5 minute period p-mode oscillations, the 160 minute oscillation, torsional oscillations, localized brightness oscillations; wave observations; waves and oscillations in sunspots; future observational needs). Oscillations as probes of the solar interior (direct method: technique and results; inversion methods: technique and applications). Title: Book-Review - Foundations of Radiation Hydrodynamics Authors: Mihalas, D.; Mihalas, B. W.; King, A. Bibcode: 1985Obs...105..238M Altcode: No abstract at ADS Title: Book-Review - Foundations of Radiation Hydrodynamics Authors: Mihalas, D.; Mihalas, B. Bibcode: 1985S&T....70..231M Altcode: No abstract at ADS Title: Analysis and interpretation of synthetic time strings of oscillation data. Authors: Mihalas, B. W.; Christensen-Dalsgaard, J.; Brown, T. M. Bibcode: 1984sses.nasa..279M Altcode: 1984sss..conf..279M Artificial strings of solar oscillation data with gaps and noise, corresponding to the output of different spatial filter functions, were analyzed. Peaks in the power spectrum are identified for values of the degree l from 0 to 18, and rotational splitting is estimated. The filters prove effective in facilitating identification of essentially all the real peaks in the power spectrum. Estimates of peak frequencies and amplitudes and rotational splitting frequencies are in reasonably good agreement with the input values. Spurious peaks in autocorrelation spectra correspond to the frequency spacing between power peaks with the same order n, differing by one or two in the degree l. Title: Self-consistent radiation-hydrodynamic equations for stellar oscillations. I - Nonlinear form Authors: Mihalas, B. W. Bibcode: 1984ApJ...284..299M Altcode: Using the correct comoving frame, or Lagrangian, equations of radiation hydrodynamics derived by Castor and Buchler, earlier discussions of radiation hydrodynamics in the nonequilibrium diffusion regime are critically examined. Comparison of corresponding equations reveals a fundamental conceptual error in previous treatments of the interaction between stellar oscillations and the radiation field. Title: Wave Propagation in a Radiating Medium Authors: Mihalas, B. W. Bibcode: 1984BAAS...16..947M Altcode: No abstract at ADS Title: On the Propagation of Acoustic Waves in a Radiative Fluid Authors: Mihalas, D.; Mihalas, B. W. Bibcode: 1984ApJ...283..469M Altcode: No abstract at ADS Title: Foundations of radiation hydrodynamics Authors: Mihalas, D.; Mihalas, B. W. Bibcode: 1984oup..book.....M Altcode: This book is the result of an attempt, over the past few years, to gather the basic tools required to do research on radiating flows in astrophysics. The microphysics of gases is discussed, taking into account the equation of state of a perfect gas, the first and second law of thermodynamics, the thermal properties of a perfect gas, the distribution function and Boltzmann's equation, the collision integral, the Maxwellian velocity distribution, Boltzmann's H-theorem, the time of relaxation, and aspects of classical statistical mechanics. Other subjects explored are related to the dynamics of ideal fluids, the dynamics of viscous and heat-conducting fluids, relativistic fluid flow, waves, shocks, winds, radiation and radiative transfer, the equations of radiation hydrodynamics, and radiating flows. Attention is given to small-amplitude disturbances, nonlinear flows, the interaction of radiation and matter, the solution of the transfer equation, acoustic waves, acoustic-gravity waves, basic concepts of special relativity, and equations of motion and energy. Title: Inferring Wave Motions: A Non-BOTE Problem Authors: Mihalas, B. W. Bibcode: 1984ssdp.conf..235M Altcode: Inferred phases are probably reliable for a very limited range of physical situations. In other situations, the uncertainties in phase arise from many effects, which the author tries to portray. Deducing phases of propagating waves, and estimating uncertainties in those phases, is a non-Back-Of-The-Envelope (non-BOTE) problem; "reasonable" approximations can easily lead to incorrect conclusions. Title: On the propagation of acoustic waves in a radiating fluid Authors: Mihalas, D.; Mihalas, B. W. Bibcode: 1983ApJ...273..355M Altcode: The linearized Lagrangian radiation equations of Castor (1972) are used in order to obtain a virtually complete and physically satisfying view of acoustic wave dynamics in a radiating fluid. It is assumed that the radiation field is quasi-static, all dynamical radiation terms are ignored, and the Eddington approximation is applied. It is noted that it would be useful to proceed with the complementary study of the time evolution of initial disturbances. Title: Internal gravity waves in the solar atmosphere. II - Effects of radiative damping Authors: Mihalas, B. W.; Toomre, J. Bibcode: 1982ApJ...263..386M Altcode: In the solar photosphere, temperature fluctuations associated with acoustic-gravity waves may be rapidly smoothed by the transfer mechanism of radiation between hotter and cooler regions. The present investigation of the radiative effects on internal gravity waves takes into account the parameterization of the radiative energy, employing the Newtonian cooling approximation. A linear analysis of the propagation of internal gravity waves is carried out in a model of the solar atmosphere which is taken to be homogeneous in the horizontal coordinates. Linear wave properties both with and without radiative cooling are summarized, and the variation with height of energy fluxes and of nonlinearities in the waves is discussed. Attention is given to the significance of the obtained results in terms of energy balance in the chromosphere and in relation to spectral line observations. Title: Internal gravity waves in the solar atmosphere. I - Adiabatic waves in the chromosphere Authors: Mihalas, B. W.; Toomre, J. Bibcode: 1981ApJ...249..349M Altcode: The properties of adiabatic and linear internal gravity waves propagating in a solar wind model are discussed, using nonlinearity criteria unique to gravity waves to estimate wave-breaking heights. The results are used to deduce information on the possible role of gravity waves in the chromospheric energy balance. Maximum vertical velocity amplitudes for gravity waves are estimated to be on the order of 2 km/sec or less, and maximum horizontal velocity amplitudes are less than 6 km/sec, with temperature perturbations as large as 1000-2000 K. It is also estimated that gravity waves with an incident energy flux of one million ergs/sq cm-sec can propagate upward to a maximum height of 900-1000 km above the visible surface before nonlinearities lead to wave breaking, while those with an energy flux of 100,000 ergs/sq cm-sec can reach maximum heights of 1400-1600 km. Title: Internal Gravity Waves? Authors: Mihalas, B. Bibcode: 1981siwn.conf...82M Altcode: No abstract at ADS Title: Internal gravity waves in the solar atmosphere Authors: Mihalas, Barbara Ruth Weibel Bibcode: 1979PhDT.......235M Altcode: No abstract at ADS Title: Internal Gravity Waves in the Solar Atmosphere. Authors: Mihalas, B. R. Bibcode: 1979PhDT.........9M Altcode: Three aspects of the behavior of gravity waves in the solar atmosphere are considered adiabatic propagation in the photosphere and chromosphere; photospheric radiative damping of waves generated by convection; and the effects of waves on spectral line profiles. The wave propagation studies are carried out with linearized fluid equations in a standard solar model. The fluid equations are reduced to a single Schroedinger-type equation in the vertical velocity, which is solved as a two-point boundary-value problem. Wave perturbations derived from this solution are used in a line transfer code to study effects of waves with varying parameters on spectra line profiles. Title: Two-dimensional radiative transfer. I. Planar geometry. Authors: Mihalas, D.; Auer, L. H.; Mihalas, B. R. Bibcode: 1978ApJ...220.1001M Altcode: Differential-equation methods for solving the transfer equation in two-dimensional planar geometries are developed. One method, which uses a Hermitian integration formula on ray segments through grid points, proves to be extremely well suited to velocity-dependent problems. An efficient elimination scheme is developed for which the computing time scales linearly with the number of angles and frequencies; problems with large velocity amplitudes can thus be treated accurately. A very accurate and efficient method for performing a formal solution is also presented. A discussion is given of several examples of periodic media and free-standing slabs, both in static cases and with velocity fields. For the free-standing slabs, two-dimensional transport effects are significant near boundaries, but no important effects were found in any of the periodic cases studied.