A Discussion on the physics of the solar atmosphere - The energy and pressure balance in the corona

1976 ◽  
Vol 281 (1304) ◽  
pp. 331-337 ◽  
Keyword(s):  
Solar Wind ◽  
Energy Balance ◽  
Solar Corona ◽  
Power Loss ◽  
Thermal Conduction ◽  
Theoretical Models ◽  
Pressure Balance ◽  
Radiated Power ◽  
Mechanical Waves ◽  
Outer Corona

This paper reviews theoretical models for the solar corona based on energy and pressure calculations. Processes included in these calculations are: ( a ) heating of the outer corona by mechanical waves; ( b ) convective out-flow of gas giving rise to the solar wind; ( c ) thermal conduction; ( d ) radiated power loss. Possible observations to help answer some of the outstanding questions about the energy balance are suggested.

Mechanisms of Heating and Heat Transfer in the Outer Solar Atmosphere

1977 ◽  
Vol 36 ◽  
pp. 223-254 ◽  
Author(s):  
M. Kuperus ◽  
C. Chiuderi
Keyword(s):  
Heat Transfer ◽  
Solar Wind ◽  
Energy Loss ◽  
Electromagnetic Radiation ◽  
Solar Atmosphere ◽  
Thermal Conduction ◽  
Interstellar Space ◽  
Outer Corona

The amount of heat required to maintain the chromosphere and corona can be found from an estimate of the losses. The two processes that transport energy from the corona into interstellar space are electromagnetic radiation and the solar wind. In the Inner corona thermal conduction constitutes the dominant means of energy loss, but convection by the solar wind gradually takes over in the outer corona.

Solar Wind Interaction and Pressure Balance at the Dayside Ionopause of Mars

2021 ◽  
Author(s):  
Feng Chu ◽  
Firdevs Duru ◽  
Zachary Girazian ◽  
Robin Ramstad ◽  
Jasper S. Halekas ◽  
...  
Keyword(s):  
Solar Wind ◽  
Pressure Balance ◽  
Solar Wind Interaction

scholarly journals Dynamics of nanodust particles emitted from elongated initial orbits

2018 ◽  
Vol 617 ◽  
pp. A43 ◽  
Author(s):  
A. Czechowski ◽  
I. Mann
Keyword(s):  
Solar Wind ◽  
Numerical Solutions ◽  
Equations Of Motion ◽  
Dust Cloud ◽  
Theoretical Models ◽  
Ecliptic Plane ◽  
Parent Body ◽  
The Sun ◽  
Trapping Region ◽  
Eccentric Orbits

Context. Because of high charge-to-mass ratio, the nanodust dynamics near the Sun is determined by interplay between the gravity and the electromagnetic forces. Depending on the point where it was created, a nanodust particle can either be trapped in a non-Keplerian orbit, or escape away from the Sun, reaching large velocity. The main source of nanodust is collisional fragmentation of larger dust grains, moving in approximately circular orbits inside the circumsolar dust cloud. Nanodust can also be released from cometary bodies, with highly elongated orbits. Aims. We use numerical simulations and theoretical models to study the dynamics of nanodust particles released from the parent bodies moving in elongated orbits around the Sun. We attempt to find out whether these particles can contribute to the trapped nanodust population. Methods. We use two methods: the motion of nanodust is described either by numerical solutions of full equations of motion, or by a two-dimensional (heliocentric distance vs. radial velocity) model based on the guiding-center approximation. Three models of the solar wind are employed, with different velocity profiles. Poynting–Robertson and the ion drag are included. Results. We find that the nanodust emitted from highly eccentric orbits with large aphelium distance, like those of sungrazing comets, is unlikely to be trapped. Some nanodust particles emitted from the inbound branch of such orbits can approach the Sun to within much shorter distances than the perihelium of the parent body. Unless destroyed by sublimation or other processes, these particles ultimately escape away from the Sun. Nanodust from highly eccentric orbits can be trapped if the orbits are contained within the boundary of the trapping region (for orbits close to ecliptic plane, within ~0.16 AU from the Sun). Particles that avoid trapping escape to large distances, gaining velocities comparable to that of the solar wind.

scholarly journals Self-Similar Theory of Thermal Conduction and Application to the Solar Wind

2015 ◽  
Vol 114 (24) ◽  
Author(s):  
K. Horaites ◽  
S. Boldyrev ◽  
S. I. Krasheninnikov ◽  
C. Salem ◽  
S. D. Bale ◽  
...  
Keyword(s):  
Solar Wind ◽  
Thermal Conduction ◽  
Self Similar ◽  
Similar Theory

scholarly journals A magnetodisc model service for planetary space weather studies

2019 ◽  
Vol 9 ◽  
pp. A24
Author(s):  
Nicholas Achilleos ◽  
Patrick Guio ◽  
Nicolas André ◽  
Arianna M. Sorba
Keyword(s):  
Solar Wind ◽  
Space Weather ◽  
Theoretical Models ◽  
Plasma Pressure ◽  
Space Environment ◽  
Solar Wind Flow ◽  
Physical Response ◽  
Global Magnetic Field ◽  
Upstream Solar Wind ◽  
Azimuthal Current

Theoretical models play an important role in the Planetary Space Weather Services (PSWS) of the European Planetary Network (“Europlanet”), due to their ability to predict the physical response of magnetospheric environments to compressions or rarefactions in the upstream solar wind flow. We illustrate this aspect by presenting examples of some calculations done with the UCL Magnetodisc Model in both “Jupiter” and “Saturn” mode. Similar model outputs can now be provided via the PSWS MAGNETODISC service. For each planet’s space environment, we present example model outputs showing the effect of compressions and rarefactions on the global magnetic field, plasma pressure and azimuthal current density. As a simple illustration of the physics underlying these reference models, we quantify solar wind effects by comparing the “compressed” and “expanded” outputs to a nominal “average-state” model, reflecting more typical solar wind dynamic pressures. We also describe the implementation of the corresponding PSWS MAGNETODISC Service, through which similar outputs may be obtained by potential users.

scholarly journals Helioseismology from space, the SOHO project

1988 ◽  
Vol 123 ◽  
pp. 545-548
Author(s):  
V. Domingo
Keyword(s):  
Solar Wind ◽  
Solar Corona ◽  
European Space Agency ◽  
Science Research ◽  
Small Scale ◽  
Heliospheric Observatory ◽  
Space Agency ◽  
Cluster A ◽  
Physics Programme

As a cornerstone of its long term plan for space science research, the European Space Agency (ESA) is developing the Solar Terrestrial Physics Programme that consists of two parts: one, the Solar and Heliospheric Observatory (SOHO) for the study of the solar internal structure and the physics of the solar corona and the solar wind, and another, CLUSTER, a series of four spacecraft flying in formation to study small scale plasma phenomena in several regions of the magnetosphere and in the near Earth solar wind. The feasibility of the missions was demonstrated in Phase A studies carried out by industrial consortia under the supervision of ESA (1,2). According to the current plans an announcement of opportunity calling for instrument proposals will be issued by ESA during the first quarter of 1987. It is foreseen that the spacecraft will be launched by the end of 1994.

scholarly journals A new formulation for the ionospheric cross polar cap potential including saturation effects

2005 ◽  
Vol 23 (11) ◽  
pp. 3533-3547 ◽  
Author(s):  
A. J. Ridley
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Mach Number ◽  
Interplanetary Magnetic Field ◽  
Polar Cap ◽  
Pressure Balance ◽  
Simple Modification ◽  
Post Shock ◽  
Cross Polar Cap Potential ◽  
New Formulation

Abstract. It is known that the ionospheric cross polar cap potential (CPCP) saturates when the interplanetary magnetic field (IMF) Bz becomes very large. Few studies have offered physical explanations as to why the polar cap potential saturates. We present 13 events in which the reconnection electric field (REF) goes above 12mV/m at some time. When these events are examined as typically done in previous studies, all of them show some signs of saturation (i.e., over-prediction of the CPCP based on a linear relationship between the IMF and the CPCP). We show that by taking into account the size of the magnetosphere and the fact that the post-shock magnetic field strength is strongly dependent upon the solar wind Mach number, we can better specify the ionospheric CPCP. The CPCP (Φ) can be expressed as Φ=(10-4v2+11.7B(1-e-Ma/3)sin3(θ/2)) {rms/9 (where v is the solar wind velocity, B is the combined Y and Z components of the interplanetary magnetic field, Ma is the solar wind Mach number, θ=acos(Bz/B), and rms is the stand-off distance to the magnetopause, assuming pressure-balance between the solar wind and the magnetosphere). This is a simple modification of the original Boyle et al. (1997) formulation.

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