Tidal Evolution of Rubble Piles (2009)
Many small bodies in the solar system are believed to be rubble piles, a collection of smaller elements separated by voids.We propose a model for the structure of a self-gravitating rubble pile....
Tidal Evolution of Rubble Piles (2007)
Many small bodies in the solar system are believed to be rubble piles, a collection of smaller elements separated by voids. We propose a model for the structure of a self-gravitating rubble pile....
Constraints on Deep-seated Zonal Winds Inside Jupiter and Saturn (2007)
Liu, Junjun, Goldreich, Peter, Stevenson, David
The atmospheres of Jupiter and Saturn exhibit strong and stable zonal winds. How deep the winds penetrate unabated into each planet is unknown. Our investigation favors shallow winds. It consists of...
Spontaneous axisymmetry breaking of Saturn's external magnetic field (2006)
Goldreich, Peter, Farmer, Alison J.
Saturn's magnetic field is remarkably axisymmetric. Its dipole axis is inclined by less than 0.2 deg with respect to its rotation axis. Rotationally driven convection of magnetospheric plasma breaks...
Imbalanced Strong MHD Turbulence (2006)
Lithwick, Yoram, Goldreich, Peter, Sridhar, S.
We present a phenomenological model of imbalanced MHD turbulence in an incompressible magnetofluid. The steady-state cascades, of waves traveling in opposite directions along the mean magnetic field,...
We compare different examples of spherical accretion onto a gravitating mass. Limiting cases include the accretion of a collisionally dominated fluid and the accretion of collisionless particles. We...
We compare different examples of spherical accretion onto a gravitating mass. Limiting cases include the accretion of a collisionally dominated fluid and the accretion of collisionless particles. We...
Folded Fields as the Source of Extreme Radio-Wave Scattering in the Galactic Center (2006)
A strong case has been made that radio waves from sources within about half a degree of the Galactic Center undergo extreme diffractive scattering. However, problems arise when standard...
Understanding the Behavior of Prometheus and Pandora (2005)
Farmer, Alison J., Goldreich, Peter
We revisit the dynamics of Prometheus and Pandora, two small moons flanking Saturn's F ring. Departures of their orbits from freely precessing ellipses result from mutual interactions via their...
Understanding the behavior of Prometheus and Pandora (2005)
Farmer, Alison J., Goldreich, Peter
We revisit the dynamics of Prometheus and Pandora, two small moons flanking Saturn's F ring. Departures of their orbits from freely precessing ellipses result from mutual interactions via their...
Spoke formation under moving plasma clouds (2005)
Farmer, Alison J., Goldreich, Peter
Goertz and Morfill (1983) propose that spokes on Saturn's rings form under radially moving plasma clouds produced by meteoroid impacts. We demonstrate that the speed at which a plasma cloud can move...
Magnetospheric eclipses in the double pulsar system J0737-3039 (2004)
Rafikov, Roman R., Goldreich, Peter
We argue that eclipses of radio emission from the millisecond pulsar A in the double pulsar system J0737-3039 are due to synchrotron absorption by plasma in the closed field line region of the...
Planet formation by coagulation: A focus on Uranus and Neptune (2004)
Goldreich, Peter, Lithwick, Yoram, Sari, Re’em
Planets form in the circumstellar disks of young stars. We review the basic physical processes by which solid bodies accrete each other and alter each others' random velocities, and we provide...
Planet Formation by Coagulation: A Focus on Uranus and Neptune (2004)
Goldreich, Peter, Lithwick, Yoram, Sari, Re'em
Planets form in the circumstellar disks of young stars. We review the basic physical processes by which solid bodies accrete each other and alter each others' random velocities, and we provide...
Final Stages of Planet Formation (2004)
Goldreich, Peter, Lithwick, Yoram, Sari, Re'em
We address three questions regarding solar system planets. What determined their number? Why are their orbits nearly circular and coplanar? How long did they take to form? Runaway accretion in a disk...
Gauge symmetry of the N-body problem in the Hamilton–Jacobi approach (2003)
Efroimsky, Michael, Goldreich, Peter
In most books the Delaunay and Lagrange equations for the orbital elements are derived by the Hamilton–Jacobi method: one begins with the two-body Hamilton equations in spherical coordinates,...
Wave damping by MHD turbulence and its effect upon cosmic ray propagation in the ISM (2003)
Farmer, Alison J., Goldreich, Peter
Cosmic rays scatter off magnetic irregularities (Alfven waves) with which they are resonant, that is waves of wavelength comparable to their gyroradii. These waves may be generated either by the...
Chaotic motions of Prometheus and Pandora (2003)
Goldreich, Peter, Rappaport, Nicole
We demonstrate that the chaotic orbits of Prometheus and Pandora are due to interactions associated with the 121:118 mean motion resonance. Differential precession splits this resonance into a...
Origin of Chaos in the Prometheus-Pandora System (2003)
Goldreich, Peter, Rappaport, Nicole
We demonstrate that the chaotic orbits of Prometheus and Pandora are due to interactions associated with the 121:118 mean motion resonance. Differential precession splits this resonance into a...
Gauge Freedom in the N-body problem of Celestial Mechanics (2003)
Efroimsky, Michael, Goldreich, Peter
We summarise research reported in (Efroimsky 2002, 2003; Efroimsky and Goldreich 2003a,b) and develop its application to planetary equations in non-inertial frames. We provide a practical example...
Planet - Disk Symbiosis (2003)
Planets form in disks around young stars. Interactions with these disks cause them to migrate and thus affect their final orbital periods. We suggest that the connection between planets and disks may...
Gauge Symmetry of the N-body Problem in the Hamilton-Jacobi Approach (2003)
Efroimsky, Michael, Goldreich, Peter
In most books the Delaunay and Lagrange equations for the orbital elements are derived by the Hamilton-Jacobi method: one begins with the 2-body Hamilton equations, performs a canonical...
Formation of Kuiper Belt Binaries (2002)
Goldreich, Peter, Lithwick, Yoram, Sari, Re'em
It appears that at least several percent of large Kuiper belt objects are members of wide binaries. Physical collisions are too infrequent to account for their formation. Collisionless gravitational...
Imbalanced Weak MHD Turbulence (2002)
Lithwick, Yoram, Goldreich, Peter
MHD turbulence consists of waves that propagate along magnetic fieldlines, in both directions. When two oppositely directed waves collide, they distort each other, without changing their respective...
Chaotic motions of [F-Ring Shepherds] Prometheus and Pandora (2002)
Goldreich, Peter, Rappaport, Nicole
Recent HST images of the Saturnian satellites Prometheus and Pandora show that their longitudes deviate from predictions of ephemerides based on Voyager images. Currently Prometheus is lagging and...
Chaotic Motions of F-Ring Shepherds (2002)
Goldreich, Peter, Rappaport, Nicole
Recent HST images of the Saturnian satellites Prometheus and Pandora show that their longitudes deviate from predictions of ephemerides based on Voyager images. Currently Prometheus is lagging and...
Eccentricity Evolution for Planets in Gaseous Disks (2002)
We investigate the hypothesis that interactions between a giant planet and the disk from which it forms promote eccentricity growth. These interactions are concentrated at discrete Lindblad and...
Tidal Evolution Of the Planetary System around HD 83443 (2001)
Two planets with orbital period ratio approximately 10:1 have been discovered around the star HD 83443. The inner and more massive planet, HD 83443b, has the smallest semi-major axis among all...
Compressible MHD Turbulence in Interstellar Plasmas (2001)
Lithwick, Yoram, Goldreich, Peter
Radio-wave scintillation observations reveal a nearly Kolmogorov spectrum of density fluctuations in the ionized interstellar medium. Although this density spectrum is suggestive of turbulence, no...
Simulations of Incompressible MHD Turbulence (2000)
Maron, Jason, Goldreich, Peter
We simulate incompressible MHD turbulence in the presence of a strong background magnetic field. Our major conclusions are: 1) MHD turbulence is most conveniently described in terms of counter...
Gravity-Modes in ZZ Ceti Stars: IV. Amplitude Saturation by Parametric Instability (2000)
ZZ Ceti stars exhibit small amplitude photometric pulsations in multiple gravity-modes. We demonstrate that parametric instability, a form of resonant 3-mode coupling, limits overstable modes to...
Growth of Perturbation in Gravitational Collapse and Accretion (1999)
When a self-gravitating spherical gas cloud collapses or accretes onto a central mass, the inner region of the cloud develops a density profile $\rho\propto r^{-3/2}$ and the velocity approaches...
A Model for the 1612 MHz Masers in OH-IR Stars (13), (1999)
Elitzur,Moshe, Goldreich,Peter, Scoville,Nick
Shklovsky (1966) first suggested that OH masers might be pumped by the absorption of infrared radiation. Subsequently, the physics of the pump process was investigated by Litvak (1969) and by Litvak...
Gravity-Modes in ZZ Ceti Stars III. Eigenvalues and Eigenfuctions (1998)
We report on numerical calculations of nonadiabatic eigenvalues and eigenfunctions for g-modes in ZZ Ceti variables. The spectrum of overstable $l=1$ modes delineates the instability strip. Its blue...
Gauge Symmetry of the N-body Problem in the Hamilton-Jacobi Approach (1998)
Efroimsky, Michael, Goldreich, Peter
In most books the Delannay and Lagrange equations for the orbital elements are derived by the Hamilton-Jacobi method: one begins with the two-body Hamilton equations in spherical coordinates,...
Gauge Freedom in the N-body Problem of Celestial Mechanics (1998)
Efroimsky, Michael, Goldreich, Peter
Whenever a standard system of six planetary equations(in the Lagrange, Delaunay, or other form) is employed, the trajectory resides on a 9(N-1)-dimensional submanifold of the 12(N-1)-dimensional...
Gravity-Modes in ZZ Ceti Stars: I.Quasiadiabatic Analysis of Overstability (1998)
We analyze the stability of g-modes in variable white dwarfs with hydrogen envelopes. In these stars, the radiative layer contributes to mode damping because its opacity decreases upon compression...