Most of this mass is in the form of plasma. Its mass, M ⊙ = 1.99 × 10 33 g, constitutes approximately 99.8% of the total mass of the system. The Sun is the most dominant object in the solar system. The present paper reviews the latest advances in observational and theoretical understanding of CMEs with the emphasis on quantitative comparisons of theory and observation. The key physics in CME dynamics is the Lorentz hoop force acting on toroidal “flux ropes,” scalable from tokamaks and similar laboratory plasma structures. Thus, a new theoretical framework with testable predictions is emerging to model eruptions and the coupling of CME ejecta to geomagnetic disturbances. Recent work has demonstrated that theoretical results can simultaneously replicate the observed CME position-time data, temporal profiles of associated solar flare soft X-ray emissions, and the magnetic field and plasma parameters of CME ejecta measured at 1 AU. New observations of CME dynamics and associated eruptive phenomena are now providing more stringent constraints on models, and quantitative theory-data comparisons are helping to establish the correct mechanism of solar eruptions, particularly the driving force of CMEs and the evolution of their magnetic fields in three dimensions. Until recently, the physical mechanisms responsible for eruptions were major unanswered questions in solar and by extension stellar physics. This has culminated in the ability to continuously observe CMEs expanding from the Sun to 1 AU, where the magnetic fields and plasma parameters of the evolved structures (“ejecta”) can be measured in situ. The scientific and practical importance of CMEs has led to numerous satellite missions observing the Sun and SW. If they reach the Earth, their magnetic fields can drive strong disturbances in the ionosphere, causing deleterious effects on terrestrial technological systems. CMEs are the central component of solar eruptions and are detected as coherent magnetized plasma structures expanding in the solar wind (SW). The solar exposure builds approximately linearly with time except for a visible modulation caused by seasonal variations.Solar eruptions, observed as flares and coronal mass ejections (CMEs), are the most energetic visible plasma phenomena in the solar system. The Earth albedo was determined from Nimbus 7 radiometer measurements reported by Smith et al.
Both form factors when averaged over a complete orbit are defined by the angle that the spacecraft's orbit plane makes with the Sun's rays and the orientation of the exposed surface with respect to the spacecraft's heading. The Earth albedo form factor for a surface on a spacecraft is a function of the position of the spacecraft relative to the Earth's illuminated hemisphere and to the orientation of the surface with respect to the local vertical direction.
The solar form factor for a surface on an orbiting spacecraft is a function of its orientation with respect to the Sun's rays. This depends upon the solar form factor for direct solar radiation and upon the Earth's albedo form factor which is then combined with an appropriate value of albedo for reflected radiation from the Earth. The rate of accumulation of solar exposure is calculated in terms of the equivalent number sun hours. Heat due to energy emitted from the planet Heat due to the portion of the solar incident energy reflected from the planet onto the LDEF Heat due to direct illumination from the sun Figure 3, Variation of the Sun's illumination with the plane of the LDEF orbit ß-angleĪngle between the plane of the orbit and the sun illumination
0 kommentar(er)
