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Sankalp Srivastava

Publications and source records attributed to Sankalp Srivastava.

2 recordsLinked to original sources

On the Relationship between Solar Spicules and Propagating Coronal Disturbances: The Role of Shocks

Spicules and propagating coronal disturbances (PCDs) are ubiquitous dynamic features of the solar atmosphere, yet their physical connection remains an open question of paramount importance to the mass and energy transport in the solar atmosphere. Using concurrent multiwavelength high-resolution observations from the Swedish 1-m Solar Telescope and the Solar Dynamics Observatory, supported with two-dimensional radiative magnetohydrodynamic (MHD) simulations, we find that i) shock waves in the chromosphere generated from non-linear wave steepening drive some spicules, ii) in the corona, these shock waves may transition into large amplitude non-linear compressive MHD waves depending on the magnetic field strength and the ambient coronal conditions. In either case, the shocks or the large-amplitude compressive waves in the corona, also transport upward mass flux and produce intensity variations in the form of PCDs in coronal passbands. Further a multi-height wavelet analysis shows dominant $\sim$5 minute periods in the lower chromosphere that evolve into longer periods ($\ge$10 minutes) at higher atmospheric layers, consistent with dispersive propagation in a stratified medium. The observational characteristics together with the numerical simulations, demonstrate that a shock-driven MHD mechanism links spicule formation to coronal disturbances. Finally, mass flux estimates from both the observations and the simulations indicate that these PCDs can also aid in supplying mass to the solar wind.

astro-ph.SR↗

The Relation between Solar Spicules and Magnetohydrodynamic Shocks

Spicules are thin, elongated jet-like features seen in observations of the solar atmosphere, at the interface between the solar photosphere and the corona. These features exhibit highly complex dynamics and are a necessary connecting link between the cooler, denser solar chromosphere and the extremely hot, tenuous corona. In this work, we explore the spatial and temporal relation between solar spicules and magneto-hydrodynamic (MHD) shocks using data from a 2D radiative MHD (rMHD) simulation of the solar atmosphere driven by solar convection. Here, we demonstrate, through direct identification, that slow MHD shocks, which propagate along magnetic field lines, are regions of strong positive vertical acceleration of the plasma that forms the tip of the spicule material during its rise phase. We quantify the effect of pressure and Lorentz forces on the acceleration of the plasma inside the shocks during the rise of spicules. The causality between spicule and shock propagation in the atmosphere of the model is also investigated. It is further shown that the strength of these shocks may play a vital role in determining the height of the spicules, supporting the idea that shocks act as drivers of some spicules. In addition, we also find the presence of structures similar to propagating coronal disturbances (PCDs) in the simulation, linked with the spicules. Here, PCDs appear to be associated with the shock waves driving the spicules that subsequently propagate into the corona and have similar speeds to those reported in observations.

astro-ph.SR↗