Search Publications
Spacecraft radial alignments for investigations of the evolution of solar wind turbulence: A review
Telloni, Daniele
With the launch of the Parker Solar Probe, BepiColombo, and Solar Orbiter missions in the three-year period 2018 - 2020 , the investigation of the evolution of solar wind turbulence, dynamics, and structures in the inner heliosphere has become more readily feasible, thanks to the increasing availability of orbital configurations suitable for multi…
Long-term solar activity studies using microwave imaging observations and prediction for cycle 25
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +1 more
We use microwave imaging observations from the Nobeyama Radioheliograph at 17 GHz for long-term studies of solar activity. In particular, we use the polar and low-latitude brightness temperatures as proxies to the polar and active-region magnetic fields, respectively. We also use the locations of prominence eruptions as a proxy to the filament loc…
Large-scale magnetic fields and anomalies of chemical composition of stellar coronae
Pipin, V. V.; Tomozov, V. M.
We present evidence that anomalies in abundance of the chemical admixtures with the low first ionization potential (FIP) in the low corona of the late-type stars can be related to a topology of the large-scale magnetic field. Observational data from Ulysses and the Stanford Solar Observatory reveal the high correlations between the FIP effect of t…
Underestimates of magnetic flux in coupled MHD model solar wind solutions
Riley, Pete; Stevens, Michael L.; Linker, Jon A. +1 more
When validated with spacecraft observations, one enduring characteristic of global MHD solar wind models is the tendency to underestimate the interplanetary magnetic flux. This study quantifies the “missing flux” problem for models used in the coordinated Center for Integrated Space Weather Modeling study of corotating interaction regions, and ide…
Solar cycle evolution of the heliospheric magnetic field: The Ulysses legacy
Smith, E. J.
Important contributions of Ulysses to understanding the solar cycle evolution of the heliospheric magnetic field (HMF) and solar wind are reviewed: a dramatic reorientation of the HMF as the solar dipole rotates between axial and equatorial orientations; solar cycle variation of the total heliospheric magnetic flux and its response to changes in s…
A computational study of nonresonant cross-field diffusion of energetic particles due to their interaction with interplanetary magnetic decreases
Costa, E.; Lakhina, G. S.; Tsurutani, B. T. +4 more
We present a new method of calculating cross-field diffusion of charged particles due to their interactions with interplanetary magnetic decreases (MDs) in high heliospheric latitudes. We use a geometric model that evaluates perpendicular diffusion to the ambient magnetic field as a function of particle's gyroradius, MD radius, ratio between field…
Observations of shock acceleration signatures by Ulysses: the 04:08:16, day147, 1991 UT shock
Sarris, E. T.; Anagnostopoulos, G. C.; Marhavilas, P. K.
We analyze the acceleration signatures of energetic ions (E>50keV) and electrons (E>30keV) observed on day 147, 1991 UT in the vicinity of the surface of a fast-mode hydromagnetic shock, using fine time resolution measurements by the HI-SCALE instrument onboard the Ulysses spacecraft. The observations present strong evidence for the accelera…