Search Publications
Testing theories of gravity with planetary ephemerides
Fienga, Agnès; Minazzoli, Olivier
We describe here how planetary ephemerides are built in the framework of General Relativity and how they can be used to test alternative theories. We focus on the definition of the reference frame (space and time) in which the planetary ephemeris is described, the equations of motion that govern the orbits of solar system bodies and electromagneti…
Proposed Resolution to the Solar Open Magnetic Flux Problem
Antiochos, Spiro K.; Wallace, Samantha; Henney, Carl J. +2 more
The solar magnetic fields emerging from the photosphere into the chromosphere and corona are comprised of a combination of closed (field lines with both ends rooted at the Sun) and open (field lines with only one end at the Sun) fields. Since the early 2000s, the magnitude of total unsigned open magnetic flux estimated by coronal models has been i…
Alfvénic fluctuations in the expanding solar wind: Formation and radial evolution of spherical polarization
Hellinger, P.; Matteini, L.; Horbury, T. S. +7 more
We investigate properties of large-scale solar wind Alfvénic fluctuations and their evolution during radial expansion. We assume a strictly radial background magnetic field B ∥ R, and we use two-dimensional hybrid (fluid electrons, kinetic ions) simulations of balanced Alfvénic turbulence in the plane orthogonal to B; the simulated plasma evolves …
New Horizons Venetia Burney Student Dust Counter Observes Higher than Expected Fluxes Approaching 60 au
Singer, Kelsi N.; Stern, S. Alan; Verbiscer, Anne +8 more
The NASA New Horizons Venetia Burney Student Dust Counter (SDC) measures dust particle impacts along the spacecraft's flight path for grains with mass ≥10‑12 g, mapping out their spatial density distribution. We present the latest SDC dust density, size distribution, and flux measurements through 55 au and compare them to numerical mode…
Radial evolution of the accuracy of ballistic solar wind backmapping
Maksimovic, M.; Démoulin, P.; Badman, S. T. +4 more
Context. Solar wind backmapping is a technique employed to connect in situ measurements of heliospheric plasma structures to their origin near the Sun. The most widely used method is ballistic mapping, which neglects the effects of solar wind acceleration and corotation and instead models the solar wind as a constant radial outflow whose speed is …
Comparative Analysis of Type III Radio Bursts and Solar Flares: Spatial Localization and Correlation with Solar Flare Intensity
Maksimovic, Milan; Szabo, Adam; Bale, Stuart D. +8 more
We present a comprehensive study of type III radio bursts and their association with solar flares of magnitude M1.0 and larger, as observed by four widely separated spacecraft (Parker Solar Probe, Solar Orbiter, STEREO-A, and Wind). Our main focus is the introduction and validation of two methods for localizing radio bursts using the available mul…
Parallel Diffusion Coefficient of Energetic Charged Particles in the Inner Heliosphere from the Turbulent Magnetic Fields Measured by Parker Solar Probe
Klein, Kristopher G.; Chen, Xiaohang; Giacalone, Joe +1 more
Diffusion coefficients of energetic charged particles in turbulent magnetic fields are a fundamental aspect of diffusive transport theory but remain incompletely understood. In this work, we use quasi-linear theory to evaluate the spatial variation of the parallel diffusion coefficient κ ∥ from the measured magnetic turbulence power spe…
Constraining the stochastic gravitational wave background using the future lunar seismometers
Zhang, Fan; Chen, Xian; Shao, Lijing +3 more
Motivated by the old idea of using the Moon as a resonant gravitational wave (GW) detector, as well as the recent updates in modeling the lunar response to GWs, we reevaluate the feasibility of using a network of lunar seismometers to constrain the stochastic GW background (SGWB). In particular, using the updated model of the lunar response, we de…
Radial Distribution of Electron Quasi-thermal Noise in the Outer Heliosphere
Chen, Ling; Li, Yi-Lun; Wu De, Jin
Voyager 1 and 2 are only the two spacecraft that have arrived and passed through the heliospheric boundaries. Based on the plasma data from the Voyager 2 spacecraft, the electron quasi-thermal noise (QTN) is investigated by using of the electron population model consisting of a core with Maxwellian distribution and a halo with kappa distribution. …
Solar wind ion charge state distributions and compound cross sections for solar wind charge exchange X-ray emission
Koutroumpa, Dimitra
Solar Wind Charge eXchange X-ray (SWCX) emission in the heliosphere and Earth's exosphere is a hard to avoid signal in soft X-ray observations of astrophysical targets. On the other hand, the X-ray imaging possibilities offered by the SWCX process has led to an increasing number of future dedicated space missions for investigating the solar wind-t…