Magnetic-Island Contraction and Particle Acceleration in Simulated Eruptive Solar Flares

The mechanism that accelerates particles to the energies required to produce the observed high-energy impulsive emission in solar flares is not well understood. Drake et al. (2006) proposed a mechanism for accelerating electrons in contracting magnetic islands formed by kinetic reconnection in multi-layered current sheets. We apply these ideas to sunward-moving flux ropes (2.5D magnetic islands) formed during fast reconnection in a simulated eruptive flare. A simple analytic model is used to calculate the energy gain of particles orbiting the field lines of the contracting magnetic islands in our ultrahigh-resolution 2.5D numerical simulation. We find that the estimated energy gains in a single island range up to a factor of five. This is higher than that found by Drake et al. for islands in the terrestrial magnetosphere and at the heliopause, due to strong plasma compression that occurs at the flare current sheet. In order to increase their energy by two orders of magnitude and plausibly account for the observed high-energy flare emission, the electrons must visit multiple contracting islands. This mechanism should produce sporadic emission because island formation is intermittent. Moreover, a large number of particles could be accelerated in each magnetohydrodynamic-scale island, which may explain the inferred rates of energetic-electron production in flares. We conclude that island contraction in the flare current sheet is a promising candidate for electron acceleration in solar eruptions.Comment: Accepted for publication in The Astrophysical Journal (2016

DVD technology for educational purposes

This review of literature is about the technology of the Digital Versatile Disc (DVD). Provided is a brief overview of information in the area of DVD technology world, the evolution of DVD technology, areas that have enhanced educational advancement, and directions to be explored

Power-Law Statistics Of Driven Reconnection In The Magnetically Closed Corona

Numerous observations have revealed that power-law distributions are ubiquitous in energetic solar processes. Hard X-rays, soft X-rays, extreme ultraviolet radiation, and radio waves all display power-law frequency distributions. Since magnetic reconnection is the driving mechanism for many energetic solar phenomena, it is likely that reconnection events themselves display such power-law distributions. In this work, we perform numerical simulations of the solar corona driven by simple convective motions at the photospheric level. Using temperature changes, current distributions, and Poynting fluxes as proxies for heating, we demonstrate that energetic events occurring in our simulation display power-law frequency distributions, with slopes in good agreement with observations. We suggest that the braiding-associated reconnection in the corona can be understood in terms of a self-organized criticality model driven by convective rotational motions similar to those observed at the photosphere.Comment: Accepted by Ap

A model for straight and helical solar jets: II. Parametric study of the plasma beta

Jets are dynamic, impulsive, well-collimated plasma events that develop at many different scales and in different layers of the solar atmosphere. Jets are believed to be induced by magnetic reconnection, a process central to many astrophysical phenomena. Within the solar atmosphere, jet-like events develop in many different environments, e.g., in the vicinity of active regions as well as in coronal holes, and at various scales, from small photospheric spicules to large coronal jets. In all these events, signatures of helical structure and/or twisting/rotating motions are regularly observed. The present study aims to establish that a single model can generally reproduce the observed properties of these jet-like events. In this study, using our state-of-the-art numerical solver ARMS, we present a parametric study of a numerical tridimensional magnetohydrodynamic (MHD) model of solar jet-like events. Within the MHD paradigm, we study the impact of varying the atmospheric plasma $\beta$ on the generation and properties of solar-like jets. The parametric study validates our model of jets for plasma $\beta$ ranging from $10^{-3}$ to $1$, typical of the different layers and magnetic environments of the solar atmosphere. Our model of jets can robustly explain the generation of helical solar jet-like events at various $\beta \le 1$. This study introduces the new result that the plasma $\beta$ modifies the morphology of the helical jet, explaining the different observed shapes of jets at different scales and in different layers of the solar atmosphere. Our results allow us to understand the energisation, triggering, and driving processes of jet-like events. Our model allows us to make predictions of the impulsiveness and energetics of jets as determined by the surrounding environment, as well as the morphological properties of the resulting jets.Comment: Accepted in Astronomy and Astrophysic

Exploring Animal-like Images in NASA Photos of Mars Using de Bono’s CoRT Thinking Skills: Alternatives, Possibilities, and Choices, Compare, and Decisions

The use of de Bono’s CoRT Thinking Skills of “Alternatives, Possibilities, and Choices,” “Compare,” and “Decisions” create opportunities for students to critically think about ideas using a new lens of thinking. The lesson was designed to accommodate twice-exceptional students, gifted students with the disabilities of dyslexia and/or dyscalculia, through three of the de Bono’s strategies integrated with activities. Gifted graduate students in this lesson were presented with an opportunity to explore and analyze the animal-like images from Mars using the three CoRT thinking skills. The photographs used in this lesson were provided by the Jet Propulsion Laboratory (JPL) and the National Aeronautics and Space Administration (NASA). They compared the Martian object resembling a groundhog and a crablike object with animals from Earth, while generating creative ideas regarding what these images might represent. Additionally, students participated in an arts-integrated crayon-rubbing activity. This component of the lesson provided an opportunity to practice the Compare thinking skill while identifying similarities and differences between the artwork and the photograph of the Martian crablike object and to gather ideas to support a decision. After analyzing the artwork and the photograph of the object, students used Edward de Bono’s Decisions thinking skill to decide which image was more realistic, the student-created art image or the photo. The results of this lesson support the premise that the three de Bono CoRT Thinking Skills called “Alternatives, Possibilities, and Choices,” “Compare”, and “Decisions” help meet the needs of twice exceptional students and promote development of critical thinking skills