164 research outputs found
The first multi-wavelength campaign of AXP 4U 0142+61 from radio to hard X-rays
For the first time a quasi-simultaneous multi-wavelength campaign has been
performed on an Anomalous X-ray Pulsar from the radio to the hard X-ray band.
4U 0142+61 was an INTEGRAL target for 1 Ms in July 2005. During these
observations it was also observed in the X-ray band with Swift and RXTE, in the
optical and NIR with Gemini North and in the radio with the WSRT. In this paper
we present the source-energy distribution. The spectral results obtained in the
individual wave bands do not connect smoothly; apparently components of
different origin contribute to the total spectrum. Remarkable is that the
INTEGRAL hard X-ray spectrum (power-law index 0.79 +/- 0.10) is now measured up
to an energy of ~230 keV with no indication of a spectral break. Extrapolation
of the INTEGRAL power-law spectrum to lower energies passes orders of magnitude
underneath the NIR and optical fluxes, as well as the low ~30 microJy (2 sigma)
upper limit in the radio band.Comment: 6 pages, 1 figure. To be published in the proceedings of the
conference "Isolated Neutron Stars: from the Interior to the Surface" (April
24-28, 2006, London, UK), eds. S. Zane, R. Turolla and D. Pag
Radio Bursts Associated with Flare and Ejecta in the 13 July 2004 Event
We investigate coronal transients associated with a GOES M6.7 class flare and
a coronal mass ejection (CME) on 13 July 2004. During the rising phase of the
flare, a filament eruption, loop expansion, a Moreton wave, and an ejecta were
observed. An EIT wave was detected later on. The main features in the radio
dynamic spectrum were a frequency-drifting continuum and two type II bursts.
Our analysis shows that if the first type II burst was formed in the low
corona, the burst heights and speed are close to the projected distances and
speed of the Moreton wave (a chromospheric shock wave signature). The
frequency-drifting radio continuum, starting above 1 GHz, was formed almost two
minutes prior to any shock features becoming visible, and a fast-expanding
piston (visible as the continuum) could have launched another shock wave. A
possible scenario is that a flare blast overtook the earlier transient, and
ignited the first type II burst. The second type II burst may have been formed
by the same shock, but only if the shock was propagating at a constant speed.
This interpretation also requires that the shock-producing regions were located
at different parts of the propagating structure, or that the shock was passing
through regions with highly different atmospheric densities. This complex
event, with a multitude of radio features and transients at other wavelengths,
presents evidence for both blast-wave-related and CME-related radio emissions.Comment: 14 pages, 6 figures; Solar Physics Topical Issue, in pres
Coronal Shock Waves, EUV waves, and Their Relation to CMEs. I. Reconciliation of "EIT waves", Type II Radio Bursts, and Leading Edges of CMEs
We show examples of excitation of coronal waves by flare-related abrupt
eruptions of magnetic rope structures. The waves presumably rapidly steepened
into shocks and freely propagated afterwards like decelerating blast waves that
showed up as Moreton waves and EUV waves. We propose a simple quantitative
description for such shock waves to reconcile their observed propagation with
drift rates of metric type II bursts and kinematics of leading edges of coronal
mass ejections (CMEs). Taking account of different plasma density falloffs for
propagation of a wave up and along the solar surface, we demonstrate a close
correspondence between drift rates of type II bursts and speeds of EUV waves,
Moreton waves, and CMEs observed in a few known events.Comment: 30 pages, 15 figures. Solar Physics, published online. The final
publication is available at http://www.springerlink.co
Magnetic Flux of EUV Arcade and Dimming Regions as a Relevant Parameter for Early Diagnostics of Solar Eruptions - Sources of Non-Recurrent Geomagnetic Storms and Forbush Decreases
This study aims at the early diagnostics of geoeffectiveness of coronal mass
ejections (CMEs) from quantitative parameters of the accompanying EUV dimming
and arcade events. We study events of the 23th solar cycle, in which major
non-recurrent geomagnetic storms (GMS) with Dst <-100 nT are sufficiently
reliably identified with their solar sources in the central part of the disk.
Using the SOHO/EIT 195 A images and MDI magnetograms, we select significant
dimming and arcade areas and calculate summarized unsigned magnetic fluxes in
these regions at the photospheric level. The high relevance of this eruption
parameter is displayed by its pronounced correlation with the Forbush decrease
(FD) magnitude, which, unlike GMSs, does not depend on the sign of the Bz
component but is determined by global characteristics of ICMEs. Correlations
with the same magnetic flux in the solar source region are found for the GMS
intensity (at the first step, without taking into account factors determining
the Bz component near the Earth), as well as for the temporal intervals between
the solar eruptions and the GMS onset and peak times. The larger the magnetic
flux, the stronger the FD and GMS intensities are and the shorter the ICME
transit time is. The revealed correlations indicate that the main quantitative
characteristics of major non-recurrent space weather disturbances are largely
determined by measurable parameters of solar eruptions, in particular, by the
magnetic flux in dimming areas and arcades, and can be tentatively estimated in
advance with a lead time from 1 to 4 days. For GMS intensity, the revealed
dependencies allow one to estimate a possible value, which can be expected if
the Bz component is negative.Comment: 27 pages, 5 figures. Accepted for publication in Solar Physic
Electronic cigarettes: A position statement from the Thoracic Society of Australia and New Zealand*
The TSANZ develops position statements where insufficient data exist to write formal clinical guidelines. In 2018, the TSANZ addressed the question of potential benefits and health impacts of electronic cigarettes (EC). The working party included groups focused on health impacts, smoking cessation, youth issues and priority populations. The 2018 report on the Public Health Consequences of E-Cigarettes from the United States NASEM was accepted as reflective of evidence to mid-2017. A search for papers subsequently published in peer-reviewed journals was conducted in August 2018. A small number of robust and important papers published until March 2019 were also identified and included. Groups identified studies that extended, modified or contradicted the NASEM report. A total of 3793 papers were identified and reviewed, with summaries and draft position statements developed and presented to TSANZ membership in April 2019. After feedback from members and external reviewers, a collection of position statements was finalized in December 2019. EC have adverse lung effects and harmful effects of long-term use are unknown. EC are unsuitable consumer products for recreational use, part-substitution for smoking or long-term exclusive use by former smokers. Smokers who require support to quit smoking should be directed towards approved medication in conjunction with behavioural support as having the strongest evidence for efficacy and safety. No specific EC product can be recommended as effective and safe for smoking cessation. Smoking cessation claims in relation to EC should be assessed by established regulators
Context, Complexity and Contestation: Birmingham's Agreed Syllabuses for Religious Education since the 1970s
publication-status: AcceptedThis is an Author's Original Manuscript of an article whose final and definitive form, the Version of Record, has been published in the Journal of Beliefs and Values, September 2011. Available online at: http://www.tandfonline.com/ or DOI: 10.1080/13617672.2011.600823The present article offers an historical perspective on the 1975, 1995 and 2007 Birmingham Agreed Syllabuses for Religious Education. It draws upon historical evidence uncovered as part of ‘The hidden history of curriculum change in religious education in English schools, 1969–1979’ project, and curriculum history theories, especially David Labaree’s observations about the distance between the ‘rhetorical’ and ‘received’ curricula. We argue that, contrary to the existing historiography, curriculum change in religious education (RE) has been evolutionary not revolutionary. Multiple reasons are posited to explain this, not least among which is the capacity and agency of teachers. Furthermore, we argue that ongoing debates about the nature and purpose of RE, as exemplified in the Birmingham context, reflect the multiple expectations that religious educators and other stakeholders had, and continue to have, of the curriculum subject. These debates contribute to the inertia evident in the implementation of RE curriculum reforms. A consciousness of the history of RE enables curriculum contestations to be contextualised and understood, and, thereby, provides important insights which can be applied to ongoing and future debates and developments
The Physical Processes of CME/ICME Evolution
As observed in Thomson-scattered white light, coronal mass ejections (CMEs) are manifest as large-scale expulsions of plasma magnetically driven from the corona in the most energetic eruptions from the Sun. It remains a tantalizing mystery as to how these erupting magnetic fields evolve to form the complex structures we observe in the solar wind at Earth. Here, we strive to provide a fresh perspective on the post-eruption and interplanetary evolution of CMEs, focusing on the physical processes that define the many complex interactions of the ejected plasma with its surroundings as it departs the corona and propagates through the heliosphere. We summarize the ways CMEs and their interplanetary CMEs (ICMEs) are rotated, reconfigured, deformed, deflected, decelerated and disguised during their journey through the solar wind. This study then leads to consideration of how structures originating in coronal eruptions can be connected to their far removed interplanetary counterparts. Given that ICMEs are the drivers of most geomagnetic storms (and the sole driver of extreme storms), this work provides a guide to the processes that must be considered in making space weather forecasts from remote observations of the corona.Peer reviewe
An Observational Overview of Solar Flares
We present an overview of solar flares and associated phenomena, drawing upon
a wide range of observational data primarily from the RHESSI era. Following an
introductory discussion and overview of the status of observational
capabilities, the article is split into topical sections which deal with
different areas of flare phenomena (footpoints and ribbons, coronal sources,
relationship to coronal mass ejections) and their interconnections. We also
discuss flare soft X-ray spectroscopy and the energetics of the process. The
emphasis is to describe the observations from multiple points of view, while
bearing in mind the models that link them to each other and to theory. The
present theoretical and observational understanding of solar flares is far from
complete, so we conclude with a brief discussion of models, and a list of
missing but important observations.Comment: This is an article for a monograph on the physics of solar flares,
inspired by RHESSI observations. The individual articles are to appear in
Space Science Reviews (2011
Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples
Large amounts of nitrogen compounds, such as ammonium salts, may be stored in icy bodies and comets, but the transport of these nitrogen-bearing solids into the near-Earth region is not well understood. Here, we report the discovery of iron nitride on magnetite grains from the surface of the near-Earth C-type carbonaceous asteroid Ryugu, suggesting inorganic nitrogen fixation. Micrometeoroid impacts and solar wind irradiation may have caused the selective loss of volatile species from major iron-bearing minerals to form the metallic iron. Iron nitride is a product of nitridation of the iron metal by impacts of micrometeoroids that have higher nitrogen contents than the CI chondrites. The impactors are probably primitive materials with origins in the nitrogen-rich reservoirs in the outer Solar System. Our observation implies that the amount of nitrogen available for planetary formation and prebiotic reactions in the inner Solar System is greater than previously recognized
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