R. T. James McAteer
New Mexico State University, Astronomy, Faculty Member
- New Mexico State University, Office of the Provost, Faculty Memberadd
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ABSTRACT In order to understand Solar Prominences, we need to observe them at sub-arcsecond resolution, with a sub-second cadence. Present image reconstruction techniques, such as Speckle Interferometry, are capable of delivering high... more
ABSTRACT In order to understand Solar Prominences, we need to observe them at sub-arcsecond resolution, with a sub-second cadence. Present image reconstruction techniques, such as Speckle Interferometry, are capable of delivering high resolution images, but at a slow cadence. We propose the design for a Solar Limb Adaptive Optics system that would allow images to be captured at sub-second cadence with sub-arcsecond resolution. The challenge, with Solar Limb AO, is the use of faint Hα prominence structure near the limb, to derive wavefront measurements at hight speed. Regular, on-disk Solar Adaptive Optics have sufficient photon flux available, for the subaperture based wavefront sensor. In contrast, a Shack Hartmann wave- front sensor, which uses faint Hα prominence structure as its reference, is photon starved. Full aperture sensor concepts, such as Phase Diversity, may have to be considered. It is hoped that such a system, if successful, would be implemented on the upcoming Advanced Technology Solar Telescope.
ABSTRACT Solar active events are the source of many energetic and geo-effective events such as solar flares and coronal mass ejections (CMEs). Understanding how these complex source regions evolve and produce these events is of... more
ABSTRACT Solar active events are the source of many energetic and geo-effective events such as solar flares and coronal mass ejections (CMEs). Understanding how these complex source regions evolve and produce these events is of fundamental importance, not only to solar physics but also the demands of space weather forecasting. In this poster, we present preliminary results from our analysis of the physical properties of active region magnetic fields using fractal-, gradient-, neutral line-, emerging flux-, and wavelet-based techniques. These analyses look to use the defined physical measures to form a predictive model for flaring behavior in active regions.
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ABSTRACT Wavelets have been very successfully used as a tool for noise reduction and general processing of images. Despite this, wavelets have inherent limitations with 2-D data. Wavelets are well suited for describing point singularities... more
ABSTRACT Wavelets have been very successfully used as a tool for noise reduction and general processing of images. Despite this, wavelets have inherent limitations with 2-D data. Wavelets are well suited for describing point singularities but much of the interesting information in images is described by edges, lines or curves. Newly developed multiscale transforms address some of these issues. The ridgelet transform takes the multiscale concept of wavelets but applies it to 1-D objects (lines) instead of 0-D objects (points). The curvelet transform likewise applies to multiscale curves. We present a preliminary study of the use of these new multiscale transforms with solar image data. These data include TRACE EUV images and LASCO coronagraph images.
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ABSTRACT Two multi-resolution analyses are used to decompose active region magnetic fields into objects of different lengthscales, allowing one to examine the structure of the active region field at different lengthscales. Lines... more
ABSTRACT Two multi-resolution analyses are used to decompose active region magnetic fields into objects of different lengthscales, allowing one to examine the structure of the active region field at different lengthscales. Lines separating opposite polarity groupings of flux at different lengthscales are found (a generalization of the notion of a magnetic neutral line). It is shown that the average magnetic field gradient for alpha, beta, beta-gamma, and beta-gamma-delta active regions increases in the order listed, and that the order is maintained over all length-scales. Since magnetic field gradient is strongly linked to active region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all lengthscales in the active region, and not just those lengthscales at which the strongest field gradients are found. Properties of these generalized neutral lines are also correlated with GOES flare activity in a search for an indicator of flare activity.
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The authors of this report met on 28-30 March 2018 at the New Jersey Institute of Technology, Newark, New Jersey, for a 3-day workshop that brought together a group of data providers, expert modelers, and computer and data scientists, in... more
The authors of this report met on 28-30 March 2018 at the New Jersey Institute of Technology, Newark, New Jersey, for a 3-day workshop that brought together a group of data providers, expert modelers, and computer and data scientists, in the solar discipline. Their objective was to identify challenges in the path towards building an effective framework to achieve transformative advances in the understanding and forecasting of the Sun-Earth system from the upper convection zone of the Sun to the Earth's magnetosphere. The workshop aimed to develop a research roadmap that targets the scientific challenge of coupling observations and modeling with emerging data-science research to extract knowledge from the large volumes of data (observed and simulated) while stimulating computer science with new research applications. The desire among the attendees was to promote future trans-disciplinary collaborations and identify areas of convergence across disciplines. The workshop combined a ...
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In renal cystic disease, fluid accumulation within cyst lumens might stretch cyst walls and in this way stimulate cell proliferation. To test this idea, the effects of mechanical stretch on Madin-Darby canine kidney cells grown as cysts... more
In renal cystic disease, fluid accumulation within cyst lumens might stretch cyst walls and in this way stimulate cell proliferation. To test this idea, the effects of mechanical stretch on Madin-Darby canine kidney cells grown as cysts in a hydrated collagen gel or as monolayers on collagen-coated Flexcell membranes were examined. The percentage of cells synthesizing DNA (labeling index) was determined by measuring bromodeoxyuridine incorporation and counting cell numbers. The distension of single cysts for 1 h by the intraluminal injection of saline failed to produce a significant increase in labeling index. The exposure of cysts for 2.5 h to 1 mM dibutyryl cAMP + 0.1 mM isobutylmethylxanthine led to a 37% increase in luminal surface area (due to stimulated fluid secretion) and a 30% increase in labeling index. The stretch (25%) of Madin-Darby canine kidney monolayers approximately doubled the labeling index between 12 and 24 h after starting the stretch. After 48 h, the cell popu...
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ABSTRACT One of the main features of the quiet solar chromosphere is the Network Bright Points (NBP), formed by emerging magnetic flux at the boundaries of supergranular cells. Using SSW IDL routines and wavelet analysis of series of... more
ABSTRACT One of the main features of the quiet solar chromosphere is the Network Bright Points (NBP), formed by emerging magnetic flux at the boundaries of supergranular cells. Using SSW IDL routines and wavelet analysis of series of images in four bandpasses (CaIIK3, Mgb1, Mgb2 and Hα core) we have detected MHD wave modes in the Network Bright Points of the solar chromosphere. The observations have been analyzed using cross‐correlation techniques and we have drawn conclusions on wave propagation and mode‐coupling. © 2007 American Institute of Physics
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Oscillations in the solar corona are studied using data from Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA). We use a wavelet analysis to search for oscillatory signals in 3D datacubes (two spatial dimensions, one... more
Oscillations in the solar corona are studied using data from Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA). We use a wavelet analysis to search for oscillatory signals in 3D datacubes (two spatial dimensions, one temporal dimension) in each of the extreme ultraviolet passbands of AIA, and apply a pixel-grouping algorithm to enable us to study coherent patches of the solar corona. By looking at regions of the corona that oscillate at similar periodicity we are able to interpret the spatial behavior of oscillations through different heights in the solar corona and transversely across the corona. We propose a method to identify and extract flows, waves, and nanoflares and determine the contribution of each of these in heating coronal plasma.
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The solar corona is millions of degrees hotter than that of the surface of the Sun and we do not know why. We attempt to resolve this long standing coronal heating problem by looking at how waves transport energy to the corona. In each... more
The solar corona is millions of degrees hotter than that of the surface of the Sun and we do not know why. We attempt to resolve this long standing coronal heating problem by looking at how waves transport energy to the corona. In each region studied the 3-minute periodicity is more frequent than the 5- minute periodicity. The number of pixels exhibiting the 3- minute periodicity is between 10% - 20% and those pixels exhibiting 5- minute periodicity is between 3% - 7% of the total number of pixels observed. Our results show 3- minute oscillations along coronal loop structures but do not show 5- minute oscillations along these same loop structures. The variation in the number of pixels exhibit- ing 3- and 5- minute periodicity is roughly the same across all regions observed leading us to infer that the 3- and 5- minute oscillation is the result of a global mechanism.
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Compact chromospheric brightenings have a range of intensities, Doppler velocities, and magnetic field strength each giving clues to their physical origin. One type of compact brightening, sequential chromospheric brightening (SCB), has... more
Compact chromospheric brightenings have a range of intensities, Doppler velocities, and magnetic field strength each giving clues to their physical origin. One type of compact brightening, sequential chromospheric brightening (SCB), has several properties of small-scale chromospheric evaporation. SCBs appear adjacent to two ribbon flares with associated halo CMEs. This work presents a definition of SCBs constrained by a statistical analysis of several chromospheric flaring events. From this definition of SCBs, we extract physical qualities of SCBs and correlate these qualities with data gathered from additional layers of the solar atmosphere. Using these dynamic measurements, we suggest a connection between compact brightenings, the erupting flare, and overarching magnetic loops.
Research Interests: Physics and Chromosphere
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Solar active regions are the source of many energetic and geo-effective events such as solar flares and coronal mass ejections (CMEs). Understanding how these complex source regions evolve and produce these events is of fundamental... more
Solar active regions are the source of many energetic and geo-effective events such as solar flares and coronal mass ejections (CMEs). Understanding how these complex source regions evolve and produce these events is of fundamental importance, not only to solar physics, but also to the demands of space weather forecasting. We propose to investigate the physical properties of active region
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The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometers... more
The solar surface and atmosphere are highly dynamic plasma environments, which evolve over a wide range of temporal and spatial scales. Large-scale eruptions, such as coronal mass ejections, can be accelerated to millions of kilometers per hour in a matter of minutes, making their automated detection and characterisation challenging. Additionally, there are numerous faint solar features, such as coronal holes and coronal dimmings, which are important for space weather monitoring and forecasting, but their low intensity and sometimes transient nature makes them problematic to detect using traditional image processing techniques. These difficulties are compounded by advances in ground- and space- based instrumentation, which have increased the volume of data that solar physicists are confronted with on a minute-by-minute basis; NASA’s Solar Dynamics Observatory for example is returning many thousands of images per hour (~1.5 TB/day). This chapter reviews recent advances in the applica...
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In the standard flare/CME model, converging magnetic field lines in the corona reconnect to release vast amounts of energy. This liberated energy is used in heating plasma, accelerating particles, and driving coronal mass ejections... more
In the standard flare/CME model, converging magnetic field lines in the corona reconnect to release vast amounts of energy. This liberated energy is used in heating plasma, accelerating particles, and driving coronal mass ejections (CMEs). This work presents tentative observational evidence of converging magnetic field lines before the initiation of a CME using the SECCHI suite of instruments onboard STEREO.
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Research Interests: Endocrinology, Pathogenesis, Biology, Immunohistochemistry, Medicine, and 15 moreHumans, Internal Medicine, Kidney, Polymerase Chain Reaction, Connective tissue, Cyst, Clinical Sciences, Epithelium, Polycystic kidney disease, Base Sequence, Enzymatic Activity, Renal artery stenosis, DNA probes, Molecular Sequence Data, and Autosomal Dominant Polycystic Kidney Disease
... Title: Science Objectives for an X-Ray Microcalorimeter Observing the Sun Authors: Laming, J. Martin; Adams, J ... Title: On Detection of Cosmic Ray Streaks in MDI Magnetograms Authors: Keys, Dustin M.; Pevtsov, A ...
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One of the most powerful SOC tools - the wavelet transform modulus maxima approach to calculating multifractality - is connected to one of the most powerful equations in all of physics - Ampere's law. In doing so, the multifractal... more
One of the most powerful SOC tools - the wavelet transform modulus maxima approach to calculating multifractality - is connected to one of the most powerful equations in all of physics - Ampere's law. In doing so, the multifractal spectra can be expressed in terms of current density, and how current density can then be used for the prediction of future energy release from such a system.
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We report multi-wavelength and multi-viewpoint observations of a solar eruptive event that involves loop–loop interactions. During a C2.0 flare, motions associated with inflowing and outflowing plasma provide evidence for ongoing magnetic... more
We report multi-wavelength and multi-viewpoint observations of a solar eruptive event that involves loop–loop interactions. During a C2.0 flare, motions associated with inflowing and outflowing plasma provide evidence for ongoing magnetic reconnection. The flare loop top and a rising " concave-up " feature are connected by a current-sheet-like structure (CSLS). The physical properties (thickness, length, temperature, and density) of the CSLS are evaluated. In regions adjacent to the CSLS, the EUV emission (characteristic temperature at 1.6 MK) begins to increase more than 10 minutes prior to the onset of the flare, and steeply decreases during the decay phase. The reduction of the emission resembles that expected from coronal dimming. The dynamics of this event imply a magnetic reconnection rate in the range 0.01–0.05.
A wavelet analysis is used to decompose active region magnetic fields into regions of different lengthscales, allowing one to examine the structure of the active region field at different lengthscales. Linesseparating opposite polarity... more
A wavelet analysis is used to decompose active region magnetic fields into regions of different lengthscales, allowing one to examine the structure of the active region field at different lengthscales. Linesseparating opposite polarity groupings of flux at different lengthscales are found; these lines can be seen as a generalization of the notion of a magnetic neutral line. It is shown
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Two different multi-resolution analyses are used to decompose the structure of active region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are... more
Two different multi-resolution analyses are used to decompose the structure of active region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are found. These lines are used as a mask on a map of the magnetic field gradient to sample the local gradient between opposite polarity regions of given scale sizes. It is shown that the maximum, average and standard deviation of the magnetic flux gradient for alpha, beta, beta-gamma and beta-gamma-delta active regions increase in the order listed, and that the order is maintained over all length-scales. This study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all length-scales in the active region, and not just those length-scales at which the strongest flux gradients are found. Further, it is also shown that the average gradients in the field, and the average length-scale at which they occur, also increase in the same order. Finally, there are significant differences in the gradient distribution, between flaring and non-flaring active regions, which are maintained over all length-scales. It is also shown that the average gradient content of active regions that have large flares (GOES class 'M' and above) is larger than that for active regions containing flares of all flare sizes; this difference is also maintained at all length-scales.
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Solar sequential chromospheric brightenings (SCBs) are typically observed in conjunction with flares that have associated coronal mass ejections (CMEs). To characterize these ephemeral events, we developed automated procedures to identify... more
Solar sequential chromospheric brightenings (SCBs) are typically observed in conjunction with flares that have associated coronal mass ejections (CMEs). To characterize these ephemeral events, we developed automated procedures to identify and track subsections of large solar flares and the SCBs using the ISOON telescope's H-alpha data. This software package extracts physical quantities such as temporal variation of flare and SCB intensities, apparent proper motion of the moving ribbons, and the speed of SCB intensity propagation. Overlying the extracted features onto complementary datasets, we obtain underlying Doppler velocity and magnetic intensity measurements. We demonstrate that flare ribbons can be fully characterized by subdividing them into discrete flare kernels. We also present evidence that SCBs are a different class of brightening than the flare ribbons.
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ABSTRACT We identify trends and patterns that may be used in automated flare detection algorithms with real-time data from the Solar Dynamics Observatory (SDO). We analyzed the magnetic field intensities and areal dimensions of active... more
ABSTRACT We identify trends and patterns that may be used in automated flare detection algorithms with real-time data from the Solar Dynamics Observatory (SDO). We analyzed the magnetic field intensities and areal dimensions of active regions that produced the 30 strongest X-class flares during solar cycle 23 (1996-2007). The data were obtained through SoHO's Michelson Doppler Imager (MDI). The magnetograms underwent thresholds to identify positive and negative polarities, 1000 and -1000 Gauss respectively. Each active region was observed several days before and up to a few hours after the flare occurred. Based on preliminary results, about one third of the flares show a similar linear growth pattern in which the flare occurs near or at the peak of growth.
This paper investigates the possibility of automating the detection of propagating intensity perturbations in coronal loops using wavelet analysis. Two different sets of TRACE 171 Å images are studied using the automated wavelet routine... more
This paper investigates the possibility of automating the detection of propagating intensity perturbations in coronal loops using wavelet analysis. Two different sets of TRACE 171 Å images are studied using the automated wavelet routine presented by McAteer et al. (2004). Both localised, short-lived periodicities and sustained, periodic, oscillations are picked up by the routine, with the results dependent to a large extent on the signal-to-noise ratio of the dataset. At present, the automation is only partial; the relevance of the detected periodicity and the identification of the coronal structure supporting it still have to be determined by the user, as does the judging of the accuracy of the results. Care has to be taken when interpreting the results of the wavelet analysis, and a good knowledge of all possible factors that might influence or distort the results is a necessity. Despite these limitations, wavelet analysis can play an important role in automatically identifying a variety of phenomena and in the analysis of the ever-growing (observational or simulated) datasets.
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ABSTRACT Solar coronal mass ejections (CMEs) are the most significant drivers of adverse space weather on Earth, but the physics governing their propagation through the heliosphere is not well understood. Although stereoscopic imaging of... more
ABSTRACT Solar coronal mass ejections (CMEs) are the most significant drivers of adverse space weather on Earth, but the physics governing their propagation through the heliosphere is not well understood. Although stereoscopic imaging of CMEs with NASA's Solar Terrestrial Relations Observatory (STEREO) has provided some insight into their three-dimensional (3D) propagation, the mechanisms governing their evolution remain unclear because of difficulties in reconstructing their true 3D structure. In this talk I will describe the use of an elliptical tie-pointing technique to reconstruct a CME front in 3D, enabling us to quantify its deflected trajectory from high latitudes along the ecliptic, and measure its increasing angular width and propagation. At large distances from the Sun (>7 R_sun), I will describe how its motion is determined by drag effects in the solar wind, using ENLIL simulations of the inner heliosphere. By combining a 3D reconstruction with modelling of the solar wind, we predict an arrival time within 30 mins of the in-situ detection of the CME at ACE
The symbiotic relationship between time-series oscillatory power and waves in the chromosphere is studied using several novel wavelet techniques. Theses include automated wave-packet searching routines for large datasets, correlation of... more
The symbiotic relationship between time-series oscillatory power and waves in the chromosphere is studied using several novel wavelet techniques. Theses include automated wave-packet searching routines for large datasets, correlation of wave-packets at multiple heights in the atmosphere, and a full multi-wavelength wavelet-phase analysis (including the cross transform, phase difference and phase coherence). In each study we interpret oscillatory power as a signature of waves in the quiet-Sun chromosphere and relate these wave modes to the underlying photospheric magnetic field.
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A 2D wavelet transform modulus maxima (WTMM) method is used to characterise the complexity of the distribution of the photospheric magnetic field of active regions. The WTMM method offers increased accuracy and reliability over previous... more
A 2D wavelet transform modulus maxima (WTMM) method is used to characterise the complexity of the distribution of the photospheric magnetic field of active regions. The WTMM method offers increased accuracy and reliability over previous fractal and multifractal methods. The multifractal spectrum of both quiet Sun and active region magnetic features are presented. It is shown that the multifractal nature of the quiet Sun is significantly different from that of an active region. As such, a method is proposed to seperate the information corresponding to the multifractal spectrum of an active region from the surrounding quite Sun texture. The WTMM method and segmentation procedure are shown to detect the internal restructuring of active region magnetic features prior to flaring. We detect two thresholds (Haussdorf dimension > 1.2 and Holder Exponent > -0.7) as possible indicators for conditions favourable to flaring.