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Warmer Local Interstellar Medium: A Possible Resolution of the Ulysses-IBEX Enigma
McComas, D. J.; Fuselier, S. A.; Kucharek, H. +9 more
Interstellar Boundary Explorer (IBEX) measurements from 2009-2010 identified a set of possible solutions with very tight coupling between the interstellar He inflow longitude, latitude, speed, and temperature. The center of this allowable parameter space suggested that the heliosphere could be moving more slowly and in a slightly different directi…
Revisiting Ulysses Observations of Interstellar Helium
Wood, Brian E.; Müller, Hans-Reinhard; Witte, Manfred
We report the results of a comprehensive reanalysis of Ulysses observations of interstellar He atoms flowing through the solar system, the goal being to reassess the interstellar He flow vector and to search for evidence of variability in this vector. We find no evidence that the He beam seen by Ulysses changes at all from 1994-2007. The direction…
On the Origin of Mid-latitude Fast Wind: Challenging the Two-state Solar Wind Paradigm
Landi, Enrico; Zurbuchen, Thomas H.; Lepri, Susan T. +2 more
The bimodal paradigm of solar wind describes a slow solar wind situated near the heliospheric current sheet while a fast wind overexpands from the poles to fill in the remainder of the heliosphere. In this paper, we challenge this paradigm and focus here on mid-latitude wind using three fast-latitude passes completed by the Ulysses spacecraft. Bas…
Sixteen Years of Ulysses Interstellar Dust Measurements in the Solar System. I. Mass Distribution and Gas-to-dust Mass Ratio
Krüger, Harald; Grün, Eberhard; Sterken, Veerle J. +1 more
In the early 1990s, contemporary interstellar dust penetrating deep into the heliosphere was identified with the in situ dust detector on board the Ulysses spacecraft. Between 1992 and the end of 2007 Ulysses monitored the interstellar dust stream. The interstellar grains act as tracers of the physical conditions in the local interstellar medium (…
A Steady-state Picture of Solar Wind Acceleration and Charge State Composition Derived from a Global Wave-driven MHD Model
Gombosi, T. I.; Lepri, S. T.; Landi, E. +7 more
The higher charge states found in slow (<400 km s-1) solar wind streams compared to fast streams have supported the hypothesis that the slow wind originates in closed coronal loops and is released intermittently through reconnection. Here we examine whether a highly ionized slow wind can also form along steady and open magnetic field…
Revisiting the ISN Flow Parameters, Using a Variable IBEX Pointing Strategy
Wurz, P.; McComas, D. J.; Fuselier, S. A. +8 more
The Interstellar Boundary Explorer (IBEX) has observed the interstellar neutral (ISN) gas flow over the past 6 yr during winter/spring when the Earth’s motion opposes the ISN flow. Since IBEX observes the interstellar atom trajectories near their perihelion, we can use an analytical model based upon orbital mechanics to determine the interstellar …
Sixteen Years of Ulysses Interstellar Dust Measurements in the Solar System. III. Simulations and Data Unveil New Insights into Local Interstellar Dust
Krüger, Harald; Sterken, Veerle J.; von Steiger, Rudolf +2 more
Interstellar dust (ISD) in the solar system was detected in situ for the first time in 1993 by the Ulysses dust detector. The study of ISD is important for understanding its role in star and solar system formation. The goal of this paper is to understand the variability in the ISD observations from the Ulysses mission by using a Monte Carlo simula…
Sixteen Years of Ulysses Interstellar Dust Measurements in the Solar System. II. Fluctuations in the Dust Flow from the Data
Krüger, Harald; Sterken, Veerle J.; Strub, Peter
The Ulysses spacecraft provided the first opportunity to identify and study interstellar dust (ISD) in situ in the solar system between 1992 and 2007. Here we present the first comprehensive analysis of the ISD component in the entire Ulysses dust data set. We analyzed several parameters of the ISD flow in a time-resolved fashion: flux, flow direc…
Deceleration of Alpha Particles in the Solar Wind by Instabilities and the Rotational Force: Implications for Heating, Azimuthal Flow, and the Parker Spiral Magnetic Field
Verscharen, Daniel; Hollweg, Joseph V.; Bourouaine, Sofiane +1 more
Protons and alpha particles in the fast solar wind are only weakly collisional and exhibit a number of non-equilibrium features, including relative drifts between particle species. Two non-collisional mechanisms have been proposed for limiting differential flow between alpha particles and protons: plasma instabilities and the rotational force. Bot…
Self-consistent Castaing Distribution of Solar Wind Turbulent Fluctuations
Perri, S.; Carbone, V.; Sorriso-Valvo, L. +2 more
The intermittent behavior of solar wind turbulent fluctuations has often been investigated through the modeling of their probability distribution functions (PDFs). Among others, the Castaing model has successfully been used in the past. In this paper, the energy dissipation field of solar wind turbulence has been studied for fast, slow, and polar …