Search Publications
Acceleration of the solar wind as a result of the reconnection of open magnetic flux with coronal loops
Fisk, L. A.
There are compelling observations of a clear anticorrelation between solar wind flow speed and coronal electron temperature, as determined from solar wind ionic charge states. A simple theory is presented which can account for these observations, including the functional form of the correlation: Solar wind flow speed squared varies essentially lin…
Using an MHD simulation to interpret the global context of a coronal mass ejection observed by two spacecraft
Lario, D.; Odstrcil, D.; Riley, Pete +4 more
In late February 1999 the ACE spacecraft observed a coronal mass ejection (CME) at 1 AU, in the ecliptic plane. Thirteen days later, Ulysses observed a CME at 5 AU and 22°S. We present a detailed analysis of the plasma, magnetic field, and composition signatures of these two events. On the basis of this comparison alone, it is not clear that the t…
Implications of the observed anticorrelation between solar wind speed and coronal electron temperature
Gloeckler, George; Geiss, Johannes; Zurbuchen, Thomas H.
Electron temperatures at the source of the solar wind are now obtained routinely and continuously from measurements of charge states of solar wind ions with modern solar wind composition spectrometers over a wide range of solar wind speeds. While the general anticorrelation between solar wind speed and electron temperature was previously noted, th…
A tilted-dipole MHD model of the solar corona and solar wind
Goldstein, M. L.; Usmanov, A. V.
We simulate the three-dimensional structure of the heliosphere during solar activity minimum by specifying boundary conditions at the coronal base. We compare the output of the model with Ulysses observations obtained during the spacecraft's first fast latitude transition in 1994-1995. The polytropic MHD equations are solved for a steady coronal o…
Consequences of proton and alpha anisotropies in the solar wind: Hybrid simulations
Goldstein, Bruce E.; Neugebauer, Marcia; Gary, S. Peter +3 more
Alfvén fluctuations propagating away from the Sun in the solar corona and solar wind transfer energy via cyclotron resonances to ions of successively larger charge-to-mass ratios. This can yield T⟂/T∥ > 1 for each ion species, where the subscripts refer to directions relative to the background magnetic field. If these anis…
Twenty-three cycles of changing open solar magnetic flux
Lockwood, M.
This paper presents a comparison of various estimates of the open solar flux, deduced from measurements of the interplanetary magnetic field, from the aa geomagnetic index and from photospheric magnetic field observations. The first two of these estimates are made using the Ulysses discovery that the radial heliospheric field is approximately inde…
Cassini between Venus and Earth: Detection of interstellar dust
Dikarev, V.; Kempf, S.; Krüger, H. +5 more
We report the successful in situ measurement of interstellar dust particles inside the orbit of the Earth with the Cosmic Dust Analyzer (CDA) on the Cassini spacecraft. The impact ionization subsystem of the CDA is similar to the instruments on Ulysses and Galileo. As the heliocentric velocity and the direction of the interstellar dust flux are we…
Observations of the Sun's magnetic field during the recent solar maximum
Hoeksema, J. T.; Appourchaux, T.; Sanderson, T. R. +1 more
We present new observations and analyses of the Sun's magnetic field and coronal holes. Using magnetic field observations from the Wilcox Solar Observatory, we present a simple means whereby the tilt angle of the current sheet can be calculated. We use a data set covering the last 26 years, which shows for the first time how the dipole component r…
Penetration of the heliosphere by the interstellar dust stream during solar maximum
Krüger, H.; Grün, E.; Altobelli, N. +1 more
We analyze the Ulysses in situ measurements of interstellar dust in the solar system with respect to the temporal variation of the flux density. The data set that is used covers the time from after Ulysses' fly-by of Jupiter up to the most recent data taken end of November 2002. The decrease in interstellar dust flux observed in 1996 can be explai…
MHD tomography using interplanetary scintillation measurement
Hayashi, Keiji; Kojima, Masayoshi; Tokumaru, Munetoshi +1 more
The MHD tomography analysis, an advanced version of the computer-assisted tomography (CAT) analysis for interplanetary scintillation (IPS) observational data, is presented. When combined with a MHD simulation, the CAT analysis can reconstruct the MHD-based three-dimensional solar wind structure within 1 AU from the IPS line-of-sight integrated vel…