692 research outputs found
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\,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 20% at an altitude of 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 8.210 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 1.810 cm.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
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