An overview of HMI off-disk flare observations

Context: White-light continuum observations of solar flares often have coronal counterparts, including the classical ``white-light prominence'' (WLP) phenomenon. Aims: Coronal emissions by flares, seen in white-light continuum, have only rarely been reported previously. We seek to use modern data to understand the morphology of WLP events. Methods: We have identified a set of 14 examples of WLP detected by the HMI (Heliospheric and Magnetic Imager) experiment on board SDO (the Solar Dynamics Observatory satellite), using a new on-line catalogue covering 2011-2017. These invariably accompanied white-light flares (WLF) emission from the lower atmosphere by flares near the limb, as identified by hard X-ray images from RHESSI (the Reuven Ramaty High Energy Spectroscopic Imager). HMI provides full Stokes information, and we have used the linear polarisations (Q~and~U) to distinguish Thomson scattering from cool material. Results: The event morphologies fit roughly into three categories: Ejection, Loop, and Spike, but many events show multiple phenomena. Conclusions: The coronal white-light continuum, observed by HMI analogously to the observations made by a coronagraph, detects many examples of coronal emission and dynamics. Using the Stokes linear polarisation, we estimate the masses of hot coronal plasma in 11 of the 14 events and find them to be similar to typical CME masses, but not exceeding 10$^{15}$\,g. We note that the HMI observations do not occult the bright solar disk and were not designed for coronal observations, resulting in relatively low signal-to-noise ratios. We therefore believe that future such observations with better optimisation will be even more fruitful.Comment: 6 pages, 6 figures, 2 tables, Accepted for publication in A&

Helioseismic and Magnetic Imager observations of linear polarization from a loop prominence system

White-light observations by the Solar Dynamics Observatory's Helioseismic and Magnetic Imager of a loop-prominence system occurring in the aftermath of an X-class flare on 2013 May 13 near the eastern solar limb show a linearly polarized component, reaching up to $\sim$20% at an altitude of $\sim$33 Mm, about the maximal amount expected if the emission were due solely to Thomson scattering of photospheric light by the coronal material. The mass associated with the polarized component was 8.2$\times$10$^{14}$ g. At 15 Mm altitude, the brightest part of the loop was 3(+/-0.5)% linearly polarized, only about 20% of that expected from pure Thomson scattering, indicating the presence of an additional unpolarized component at wavelengths near Fe I (617.33 nm), probably thermal emission. We estimated the free electron density of the white-light loop system to possibly be as high as 1.8$\times$10$^{12}$ cm$^{-3}$.Comment: 9 pages, 5 figure

The 2010 August 01 type II burst: A CME-CME Interaction, and its radio and white-light manifestations

We present observational results of a type II burst associated with a CME-CME interaction observed in the radio and white-light wavelength range. We applied radio direction-finding techniques to observations from the STEREO and Wind spacecraft, the results of which were interpreted using white-light coronagraphic measurements for context. The results of the multiple radio-direction finding techniques applied were found to be consistent both with each other and with those derived from the white-light observations of coronal mass ejections (CMEs). The results suggest that the Type II burst radio emission is causally related to the CMEs interaction.Comment: 7 pages, 6 figures, Accepted to ApJ: January 16, 201

Observations of Thomson scattering from a loop-prominence system

We describe observations of the white-light structures in the low corona following the X8.2 flare SOL 2017-09-10, as observed in full Stokes parameters by the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. These data show both bright loops and a diffuse emission region above them. We interpret the loops as the white-light counterpart of a classical loop-prominence system, intermediate between the hot X-ray loops and coronal rain. The diffuse emission external to the loops is linearly polarized and has a natural interpretation in terms of Thomson scattering from the hot plasma seen prior to its cooling and recombination. The polarimetric data from HMI enable us to distinguish this contribution of scattering from the HMI pseudocontinuum measurement, and to make a direct estimation of the coronal mass in the polarized source. For a snapshot at 16:19 UT, we estimate a mass 8 × 1014 g. We further conclude that the volumetric filling factor of this source is near unity

Periodicities in an active region correlated with Type III radio bursts observed by Parker Solar Probe

Context. Periodicities have frequently been reported across many wavelengths in the solar corona. Correlated periods of ~5 minutes, comparable to solar p-modes, are suggestive of coupling between the photosphere and the corona. Aims. Our study investigates whether there are correlations in the periodic behavior of Type III radio bursts, indicative of non-thermal electron acceleration processes, and coronal EUV emission, assessing heating and cooling, in an active region when there are no large flares. Methods. We use coordinated observations of Type III radio bursts from the FIELDS instrument on Parker Solar Probe (PSP), of extreme ultraviolet emissions by the Solar Dynamics Observatory (SDO)/AIA and white light observations by SDO/HMI, and of solar flare x-rays by Nuclear Spectroscopic Telescope Array (NuSTAR) on April 12, 2019. Several methods for assessing periodicities are utilized and compared to validate periods obtained. Results. Periodicities of about 5 minutes in the EUV in several areas of an active region are well correlated with the repetition rate of the Type III radio bursts observed on both PSP and Wind. Detrended 211A and 171A light curves show periodic profiles in multiple locations, with 171A peaks lagging those seen in 211A. This is suggestive of impulsive events that result in heating and then cooling in the lower corona. NuSTAR x-rays provide evidence for at least one microflare during the interval of Type III bursts, but there is not a one-to-one correspondence between the x-rays and the Type-III bursts. Our study provides evidence for periodic acceleration of non-thermal electrons (required to generate Type III radio bursts) when there were no observable flares either in the x-ray data or the EUV. The acceleration process, therefore, must be associated with small impulsive events, perhaps nanoflares

The need for focused, hard X-ray investigations of the Sun

Understanding the nature of energetic particles in the solar atmosphere is one of the most important outstanding problems in heliophysics. Flare-accelerated particles compose a huge fraction of the flare energy budget; they have large influences on how events develop; they are an important source of high-energy particles found in the heliosphere; and they are the single most important corollary to other areas of high-energy astrophysics. Despite the importance of this area of study, this topic has in the past decade received only a small fraction of the resources necessary for a full investigation. For example, NASA has selected no new Explorer-class instrument in the past two decades that is capable of examining this topic. The advances that are currently being made in understanding flare-accelerated electrons are largely undertaken with data from EOVSA (NSF), STIX (ESA), and NuSTAR (NASA Astrophysics). This is despite the inclusion in the previous Heliophysics decadal survey of the FOXSI concept as part of the SEE2020 mission, and also despite NASA's having invested heavily in readying the technology for such an instrument via four flights of the FOXSI sounding rocket experiment. Due to that investment, the instrumentation stands ready to implement a hard X-ray mission to investigate flare-accelerated electrons. This white paper describes the scientific motivation for why this venture should be undertaken soon.Comment: White paper submitted to the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033; 15 pages, 5 figure

To the public space of quality: a look from Barranquilla

Barranquilla en la búsqueda de su Re-conceptualización como ciudad integral y en apuesta a el mejoramiento de su infraestructura urbana, ha propuesto impulsar el potencial que representan los escenarios públicos en la cotidianidad de la ciudadanía, elementos dinamizadores como los parques y plazas, son tomados como piezas fundamentales para el estudio, análisis y critica de su funcionalidad como ente estructurante del urbanismo en el presente artículo. Logrando de esta forma un comparativo entre la cantidad, calidad y eficiencia de los espacios públicos que posee la ciudad, teniendo en cuenta características de su estado, apreciación e importancia que representa para la población y el impacto de este elemento en el ámbito urbano. Obteniendo a raíz de esto, aspectos subjetivos y objetivos que permiten una valoración completa, un abordaje sistémico del concepto de espacio público. Las variantes que se encuentran al analizar el espacio público en la ciudad dependen de su ubicación o contexto, área, componentes y población o área de influencia que es beneficiada con este, esto pone en una disyuntiva de como realmente ser objetivos a la hora de comparar las muestras, en qué criterios se puede basar para lograr una concepción de un espacio público eficiente, pero que al mismo tiempo se rija por las necesidades y requerimientos de quienes lo habitan, el cual es concebido como todo aquel espacio o área exterior que es de interés público; de todos y para todos, donde puedes ser libre de hacer lo que desees pero respetando el derecho de los demás ciudadanos.Barranquilla in the search of its Re-conceptualization as integral city and in bet to the improvement of its urban infrastructure, has proposed to promote the potential that represent the public scenarios in the daily life of the citizens, dynamic elements such as parks and squares, are taken as fundamental pieces for the study, analysis and critique of its functionality as structuring entity of urbanism in this article. Achieving in this way a comparison between the quantity, quality and efficiency of the public spaces that the city possesses, taking into account characteristics of its state, appreciation and importance that it represents for the population and the impact of this element in the urban environment. Obtaining as a result of this, subjective and objective aspects that allow a complete evaluation, a systemic approach of the concept of public space. The variants found when analyzing the public space in the city depend on its location or context, area, components and population or area of influence that is benefited with it, this puts in a dilemma of how to really be objective when comparing the samples, on what criteria can be based to achieve a conception of an efficient public space, but at the same time governed by the needs and requirements of those who inhabit it, which is conceived as all that space or exterior area that is public interest; of all and for all, where you can be free to do what you want but respecting the rights of other citizens

Desarrollo de herramientas metodológicas para incorporar contenidos de ciencia al aula y su valoración económica

La ciencia y la tecnología juegan un papel fundamental en nuestra sociedad. En este sentido, la ciudadanía parece necesitar unos conocimientos básicos que le permitan responder de manera autónoma a multitud de situaciones, tanto a nivel personal como social (Kolstø et al., 2006). Este requisito, conocido en la literatura como alfabetización científica, lleva siendo uno de los objetivos de la educación en las últimas décadas (Hodson, 2003; Feinstein, 2011). Sin embargo, parece que su consecución presenta algunos problemas. Una de las causas de estas dificultades parece ser la falta de conexión entre los contenidos que se trabajan en las clases y el día a día del ciudadano. Respecto a esto, una solución ampliamente citada en la literatura es contextualizar el aprendizaje, relacionando los contenidos trabajados en clase con escenarios cotidianos y familiares para el alumnado (Clegg & Kolodner, 2014). El proyecto pretendía que nuestros estudiantes llevasen a cabo un análisis de los contextos con contenidos científico-económicos y promovieran su utilización en el aula y en su futuro profesional. Es decir, formar a nuestros profesionales para que pudieran detectar e incorporar entre sus competencias la capacidad de conectar lo aprendido en las asignaturas con las necesidades sociales. En concreto, el proyecto tenía, en base a los problemas detectados en la percepción de la ciencia y en la formación de los ciudadanos, dos grandes tipos de objetivos: Objetivos relacionados con la percepción de los conocimientos científico-tecnológicos y su valoración económica (Ezquerra, Fernández-Sánchez, Cabezas, 2013; Ezquerra, Fernandez-Sanchez, 2014; Ezquerra, Fernandez-Sanchez, Magaña, 2015; 2016; Ezquerra, Fernandez-Sanchez, Magaña & Mingo, 2017): • Identificar en qué situaciones los ciudadanos, en su vida cotidiana, están en presencia de contenidos científicos o tecnológicos. • Determinar de qué modo llegan al ciudadano estos contenidos, con qué intensidad, cómo son propuestos, cómo son percibidos... • Analizar el modo en que podemos otorgar a estos contenidos una valoración económica. Objetivos educativos que se integran dentro de las asignaturas: • Analizar las correspondencias entre los currículos oficiales y los contenidos presentes en el entorno del ciudadano (Ezquerra, Fernandez-Sanchez, Magaña Ramos, 2015; Ezquerra y Magaña, 2016). • Introducir a los estudiantes en una propuesta de aprendizaje basada en la indagación (Rivero et al., 2013; Ezquerra, De Juanas, Martín del Pozo, 2015). • Valorar las estrategias y competencias de los futuros docentes para vincular sus conocimientos con la realidad circundante (De Juanas et al., 2012). • Analizar las actividades que los estudiantes propongan para identificar los contenidos de ciencia y estudiar su valoración económica