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Flux conservation, radial scalings, Mach numbers, and critical distances in the solar wind: magnetohydrodynamics and Ulysses observations
DOI: 10.1093/mnras/stab2051 Bibcode: 2021MNRAS.506.4993V

Verscharen, Daniel; Velli, Marco; Bale, Stuart D.

One of the key challenges in solar and heliospheric physics is to understand the acceleration of the solar wind. As a super-sonic, super-Alfvénic plasma flow, the solar wind carries mass, momentum, energy, and angular momentum from the Sun into interplanetary space. We present a framework based on two-fluid magnetohydrodynamics to estimate the flu…

2021 Monthly Notices of the Royal Astronomical Society
SolarOrbiter Ulysses 20
Solar wind temperature-velocity relationship over the last five solar cycles and Forbush decreases associated with different types of interplanetary disturbance
DOI: 10.1093/mnras/staa3366 Bibcode: 2021MNRAS.500.2786M

Melkumyan, A. A.; Belov, A. V.; Abunina, M. A. +4 more

The behaviour of the solar wind (SW) proton temperature and velocity and their relationship during Forbush decreases (FDs) associated with various types of solar source - coronal mass ejections (CMEs) and coronal holes (CHs) - have been studied. Analysis of cosmic ray variations, SW temperature, velocity, density, plasma beta, and magnetic field (…

2021 Monthly Notices of the Royal Astronomical Society
SOHO Ulysses 11
Searching for gravitational waves via Doppler tracking by future missions to Uranus and Neptune
DOI: 10.1093/mnrasl/slab025 Bibcode: 2021MNRAS.503L..73S

Saha, Prasenjit; D'Orazio, Daniel J.; Soyuer, Deniz +1 more

The past year has seen numerous publications underlining the importance of a space mission to the ice giants in the upcoming decade. Proposed mission plans involve a ∼10 yr cruise time to the ice giants. This cruise time can be utilized to search for low-frequency gravitational waves (GWs) by observing the Doppler shift caused by them in the Earth…

2021 Monthly Notices of the Royal Astronomical Society
Ulysses 11
Generalized anisotropic κ-cookbook: 2D fitting of Ulysses electron data
DOI: 10.1093/mnras/staa3641 Bibcode: 2021MNRAS.501..606S

Fichtner, H.; Scherer, K.; Lazar, M. +1 more

Observations in space plasmas reveal particle velocity distributions out of thermal equilibrium, with anisotropies (e.g. parallel drifts and/or different temperatures, T - parallel and T - perpendicular, with respect to the background magnetic field), and multiple quasi-thermal and suprathermal populations with different pr…

2021 Monthly Notices of the Royal Astronomical Society
Ulysses 11
Charge-exchange soft X-ray emission of highly charged ions with inclusion of multiple-electron capture
DOI: 10.1093/mnras/stab2537 Bibcode: 2021MNRAS.508.2194L

Cui, W.; Zhao, G.; Wu, Y. +7 more

Charge exchange has been recognized as a primary source of soft X-ray emission in many astrophysical outflow environments, including cometary and planetary exospheres impacted by the solar wind. Some models have been set up by using different data collections of charge-exchange cross-sections. However, multiple-electron transfer has not been inclu…

2021 Monthly Notices of the Royal Astronomical Society
Ulysses 8