90 research outputs found
STBadman/PSP-E10-Sources: Initial-Submission
No full textThis release is for the initial iteration of this repository and the figures it creates to support submission of the associated manuscript "Prediction and Verification of Parker Solar Probe Solar Wind Sources at 13.3 R⊙" by Badman et al., submitted to JGR Space Physics on 1/31/202
Can We Recover 3D Magnetic Topology in Sunspots Directly from Observation?
No full text<p>Poster presented by Summer Undergraduate Research Experience (SURE) student Samuel Badman (Oxford) at the Irish National Astronomy Meeting in TCD (www.inam2014.com). </p>
<p>Abstract: We use Hα 656.28nm data of the upper chromosphere from the CRISP spectropolarimeter at the SST of Active Region 11856. For the sunspot, we produce:</p>
<p>• Dominant Period maps at unprecedented resolution from iterative polynomial fitting of pixel time-series power spectra.</p>
<p>• Resultant B-field inclination maps. (See Background)</p>
<p>• Magnetograms of the lower solar photospheric surface show compelling similarity.</p
STBadman/ParkerSolarWind: Release to Zenodo
No full text<p>As with prior release, now with Zenodo enabled for archiving.</p>
STBadman/Radio-Public: Initial Release
No full text<p>Initial release of a jupyter notebook and conda environment demonstrating how to reconstruct the apparent trajectory of a solar type III radio burst using time delay of arrival (TDOA) analysis of interplanetary radio spectra from WAVES instruments on STEREO A, STEREO B and Wind</p>
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Revealing the Magnetic Structure of the Solar Corona and Inner Heliosphere in the Era of Parker Solar Probe
No full textThe Sun’s atmosphere is a complex and dynamic magnetized plasma and extends all theway from its visible surface out into interplanetary space, carving out a bubble in the inter-
stellar medium which is called the heliosphere. All interactions between the Sun and life on
Earth are channelled through this medium. Of particular importance to making Sun-Earth
connections are the regions called the corona and the inner heliosphere. These two regimes
are strongly coupled together but their mutual boundary may be regarded as the location
where the dynamic pressure of the outflowing solar wind overcomes the magnetic pressure of
the Sun’s intrinsic field. By inner heliosphere, we focus on the portion of the Sun’s sphere of
influence which extends out to 1 au and therefore is most relevant to the Earth and humanity.Our most complete understanding of the corona and heliosphere comes from large scalephysical models which can fill in information about a plasma on a 3D grid. In 2018, Parker
Solar Probe (PSP) was launched into an orbit taking it closer to the Sun than any human-
made object in history. This has presented an opportunity to directly probe regions of the
heliosphere which had hitherto could only be accessed with global modelling. In this body
of work we use new data from PSP to improve our knowledge and understanding of this
global structure and further derive novel constraints on plasma models of the corona and
heliosphere.Specifically, we first introduce a framework for evaluating models of the coronal magneticfield, which sets how the solar wind emerges and shapes the inner heliosphere. In addition
to new PSP data which provides direct boundary conditions on the magnetic skeleton of the
corona, we show how it is important to make use of pre-existing observational capabilities
to constrain the sizes of coronal holes and the locations of high plasma density indicating
the topology of the coronal streamer belt. We illustrate how models must be constrained
at multiple boundaries to give an accurate representation and that focusing on individual
specific metrics can lead to different conclusions about optimum model parameters.Next, we use the full data set of the heliospheric magnetic field taken by Parker Solar Probein its first four years on orbit to directly measure the heliospheric magnetic field down to
0.13 au and compare directly to the large scale expectations of the Parker magnetic field.
We present evidence that at 0.13 au the heliospheric magnetic field remains latitudinally
isotropic, indicating the coronal field has already relaxed to this state within this radius.
We measure the open magnetic flux and confirm it is conserved between 1 au and PSP’s
closest approach to date. This conservation implies a deficit in open magnetic flux according
to coronal models with typically accepted model parameters. We also compare the mean
direction of the heliospheric magnetic field to the expectation of the Parker spiral model,
finding very good agreement which is tending to improve with closing distance from the sun
as the ratio of average field strength to random fluctuations increases.Third, we present a study in which we determine Parker Solar Probe’s magnetic connectivityback to specific coronal sources for its first solar encounter. This exercise allows determi-
nation of specific locations on the Sun which emit solar wind plasma later measured by
PSP, and therefore contextualises its measurements. This application of combining coronal
modelling and PSP data shows how making these connections is a vital building block for
understanding other peculiar plasma physics observed as PSP as it has explored new re-
gions of the inner heliosphere. Further, it allows disambiguation of spatial and temporal
phenomena.Finally, we present recent work using observations by Parker Solar Probe and other 1 auspacecraft to localise type III radio bursts, an impulsive solar ejection of electron beams,
from emission at the solar surface out into the inner heliosphere. These events have the
potential to act as passive tracers of coronal and heliospheric structure. We comment on
the future prospects of using this localisation to constrain magnetic connectivity and density
structure.We close with a summary of these results and the outlook for further improvement of ourunderstanding of the coupled corona and inner heliosphere ans PSP continues to approach
the Sun and as other advances in space based instrumentation are made, such as the gradual
escape of the Solar Orbiter to higher latitudes.The individual investigations, which are briefly introduced above, are united in highlightingseveral specific advances in our understanding of the Sun’s atmosphere facilitated by the ad-
dition of Parker Solar Probe to humanity’s suite of heliospheric instrumentation. Specifically,
we exemplify how multi-point, multi-spacecraft and multi-messenger observations at differ-
ent heliographic locations are vital in making progress in constraining our physical models;
using just one vantage point or one physical observable can lead to false conclusions about
model optimisation. We also observe an underlying thread of the surprising utility of the
very simplest model representations of the corona and heliosphere, for example a current-
free corona and essentially hydrodynamic heliosphere can accurately predict the magnetic
polarity structure, and even the velocity stream structure measured in situ by PSP. Lastly,
we verify that as one would expect from sending an instrument to never-before explored
regions of interplanetary space, new gaps in our understanding are identified. For example,
confirming that coronal models do not open enough magnetic flux to the inner heliosphere,
or showing at several points that while we make substantial progress exploring closer to the
Sun, a lack of far-side and high latitude remote sensing (most critically of the photospheric
magnetic field), remains a big limitation to accurately reproducing the physical structure of
the heliosphere
Simplified CME and SA Stream Model for the March 16, 2023 SA Stream
No full text<p>Comparison of spacecraft trajectory and the SA stream with CME propagation based on a simplistic ice cream cone model (Na et al. 2017) in the inertial coordinate frame. The CME trajectory is shown in pink, the SA stream is in purple, and spacecraft trajectories at in black (Parker), blue (Solar Orbiter), and green (1AU). </p>
Care as an alternative to killing? Reconceptualising veterinary end of life care for animals
No full textThis is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Palliative care is routinely offered to humans in the UK, while euthanasia remains illegal. The converse is true for nonhuman animals (henceforth animals). Indeed, euthanasia is widely accepted as the appropriate course of action for “suffering” animals, and for those whose behaviours or suspected ill health are thought to pose a threat to others. This article details examples of nonhuman death at a multi-faith ashram whose members vehemently oppose all forms of killing on religious grounds. Through exploring their efforts in palliative care for animals, and their emphasis on natural death as a means of respecting the sanctity of life, the practical, emotional and theoretical viability of caring for, instead of killing, other animals at the ends of their lives is considered. In the process, normative distinctions between different categories of animals, (including humans), and different approaches to end of life care (palliative care, euthanasia, natural death) are called into question. Indeed, paying mindful attention to the diverse ways in which individual animals are cared for as they die reveals the potential violence inherent in both palliative care leading to natural death, and euthanasia, blurring perceptions of good and bad death in both veterinary and human medicine
pfsspy: A Python package for potential field source surface modelling
No full textMagnetic fields play a crucial role in the dynamics and evolution of our Sun and other stars.
A common method used to model the magnetic fields in solar and stellar atmospheres is the
potential field source surface (PFSS) model (Altschuler & Newkirk, 1969; Schatten, Wilcox,
& Ness, 1969). The PFSS equations assume that there is zero electrical current in the domain
of interest, leading to the equations //
∇ · B = 0; ∇ × B = 0 (1) //
These are solved in a spherical shell between the surface of the star and a configurable outer
radius called the ‘source surface’. Boundary conditions are given by the user specified radial
component of B on the inner boundary and the imposed condition of a purely radial field on
the source surface, which mimics the effect of the escaping stellar wind.
Historically, either custom implementations or the pfsspack1
IDL library have been used to
perform PFSS extrapolations. As Python has become a major programming language within
the solar physics and wider astronomy community (Bobra et al., 2020), there is a need to
provide well documented and tested functionality to perform PFSS extrapolations within the
Python ecosystem, a niche that pfsspy fills
"The people's champion" : folk heroism and the oral artistry of Muhammad Ali, 2000
No full textLong after a career that was as much marred by criticism as marked by accomplishment, Muhammad Au receives considerable public acclaim for his athletic accomplishments and his humanitarianism. However, no scholarly attention has been given to this man as a literary force who, through the power of his word, impacted the consciousness of this nation and world. This dissertation examines Ali as an artist operating within the context of African and African American oral literary traditions and will explore the impact of his oratory on the sociopolitical consciousness of this country. The analysis of the oral literature of Muhammad Ali, which consists of his lectures, interviews, and poetry, will involve an assessment of those aspects that make it a manifestation of the verbal culture of Africa and African America. Moreover, the study illustrates the degree to which the rhetoric and verse reflects both African-American national consciousness (i.e., black nationalism) and African folkloric tradition. In his creation of himself Ali utilizes traditional African and African American mythoforms like the trickster, the Badman, and the culture hero. In this respect, Muhammad Ali is the only athlete to emerge as an Afrocentric cultural hero. This subject encompasses matter of literature, African American studies, speech communications, and popular culture
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