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Solar flares are due to the catastrophic release of magnetic energy in the Suns corona, resulting in plasma heating, mass motions, particle acceleration, and radiation emitted from radio to $gamma$-ray wavelengths. They are associated with global coronal eruptions of plasma into the interplanetary medium---coronal mass ejections---that can result in a variety of space weather phenomena. Flares release energy over a vast range of energies, from $sim!10^{23}$ ergs (nanoflares) to more than $10^{32}$ ergs. Solar flares are a phenomenon of general astrophysical interest, allowing detailed study of magnetic energy release, eruptive processes, shock formation and propagation, particle acceleration and transport, and radiative processes. Observations at radio wavelengths offer unique diagnostics of the physics of flares. To fully exploit these diagnostics requires the means of performing time-resolved imaging spectropolarimetry. Recent observations with the Jansky Very Large Array (JVLA) and the Expanded Owens Valley Solar Array (EOVSA), supported by extensive development in forward modeling, have demonstrated the power of the approach. The ngVLA has the potential to bring our understanding of flare processes to a new level through its combination of high spatial resolution, broad frequency range, and imaging dynamic range---especially when used in concert with multi-wavelength observations and data at hard X-ray energies.
Energy stored in the magnetic field in the solar atmosphere above active regions is a key driver of all solar activity (e.g., solar flares and coronal mass ejections), some of which can affect life on Earth. Radio observations provide a unique diagno
Most massive galaxies are now thought to go through an Active Galactic Nucleus (AGN) phase one or more times. Yet, the cause of triggering and the variations in the intrinsic and observed properties of AGN population are still poorly understood. Youn
This chapter reviews some of the expected contributions of the ngVLA to the understanding of the late evolutionary stages of low-to-intermediate mass stars, including asymptotic giant branch (AGB) stars, post-AGB stars, and pre-planetary nebulae. Suc
The science case and associated science requirements for a next-generation Very Large Array (ngVLA) are described, highlighting the five key science goals developed out of a community-driven vision of the highest scientific priorities in the next dec
The next-generation Very Large Array (ngVLA) is an astronomical observatory planned to operate at centimeter wavelengths (25 to 0.26 centimeters, corresponding to a frequency range extending from 1.2 to 116 GHz). The observatory will be a synthesis r