Search Publications
Helioseismic Constraints on the Gradient of Angular Velocity at the Base of the Solar Convection Zone
Kosovichev, A. G.
The layer of transition from the nearly rigid rotation of the radiative interior to the latitudinal differential rotation of the convection zone plays a significant role in the internal dynamics of the Sun. Using rotational splitting coefficients of the p-mode frequencies, obtained during 1986--1990 at the Big Bear Solar Observatory, we have found…
Volumetric heating in coronal streamers
Wu, S. T.; Suess, S. T.; Wang, A. -H.
The addition of a volumetric heat source to a coronal streamer model produces distinct, important changes in the model. Originally, such heating was added to meet the observational requirement for a thin current sheet above streamers. Here we report additional consequences of a volumetric heat source, together with the effects of redistribution of…
Intercombinations and Allowed Transitions in O IV
Judge, P. G.; Brekke, P.; Brage, Tomas
We report on large-scale ab initio multiconfiguration Hartree-Fock calculations for important multiplets including the UV 0.01 multiplet, 2s22p2PJ-2s2p2 4Pj', in O IV. The resulting transition probabilities should be accurate to ±5%-10% for intersystem lines and 1% or better for per…
Radiometric calibration of the telescope and ultraviolet spectrometer SUMER on SOHO
Wilhelm, Klaus; Schühle, Udo; Curdt, Werner +4 more
The prelaunch spectral-sensitivity calibration of the solar spectrometer SUMER (Solar Ultraviolet Measurements of Emitted Radiation) is described. SUMER is part of the payload of the Solar and Heliospheric Observatory (SOHO), which begins its scientific mission in 1996. The instrument consists of a telescope and a spectrometer capable of taking sp…
Perspectives in Helioseismology
Scherrer, P. H.; Toomre, J.; Gough, D. O. +1 more
Helioseismology is probing the interior structure and dynamics of the sun with ever-increasing precision, providing a well-calibrated laboratory in which physical processes can be studied under conditions that are unattainable on Earth. Nearly 10 million resonant modes of oscillation are observable in the solar atmosphere, and their frequencies ne…
The 1990 May 24 Solar Cosmic-Ray Event
Vainio, R.; Torsti, J.; Anttila, A. +2 more
This paper presents an integrated analysis of GOES 6, 7 and neutron monitor observations of solar cosmic-ray event following the 1990 May 24 solar flare. We have used a model which includes particle injection at the Sun and at the interplanetary shock front and particle propagation through the interplanetary medium. The model does not attempt to s…
Latitudinal dependence of the radial IMF component - interplanetary imprint.
Phillips, J.; Smith, E. J.; Goldstein, B. E. +2 more
Ulysses measurements have confirmed that there is no significant gradient with respect to heliomagnetic latitude in the radial component, B_r_, of the interplanetary magnetic field. There are two processes responsible for this observation. In the corona, the plasma β is <<1, except directly above streamers, so both longitudinal and latitudin…
Theoretical amplitudes of solar g-modes.
Andersen, B. N.
This work presents predictions on the amplitudes of solar g-modes. It is based on the assumption that convective overshoot into the convectively stable interior generates gravity waves. Based on this assumption it is possible to estimate values for the amplitude of the g-modes below the solar convection zone. Numerical simulations, giving the tran…
Propagation of three-dimensional Alfvén waves in a stratified, thermally conducting solar wind
Orlando, S.; Peres, G.; Rosner, R. +1 more
We model the propagation of three-dimensional, adiabatic, linear Alfvén waves in the solar atmosphere and wind, taking into account relevant physical effects, including gravity stratification, thermal conduction, radiative losses, and heating (via a phenomenological term). Our magnetohydrodynamic solar wind model also accounts for the momentum dep…
The Interstellar Gas Flow Through the Heliospheric Interface Region
Fahr, Hans J.
The relative motion of the solar system with respect to the ambient interstellar medium forms a plasma interface region where the eventually subsonic, interstellar and solar wind plasma flows adapt to each other. In this region ahead of the solar system magnetohydrodynamically perturbed plasma flows are formed which, however, can be penetrated by …