A5049141219- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Stellar, planetary, and galactic studies
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Solar Radiation and Photovoltaics
- Gamma-ray bursts and supernovae
- Magnetic confinement fusion research
- Earthquake Detection and Analysis
- Spacecraft Design and Technology
- Spacecraft and Cryogenic Technologies
- Oil, Gas, and Environmental Issues
- Advanced Thermodynamics and Statistical Mechanics
- Calibration and Measurement Techniques
- Laser-induced spectroscopy and plasma
- Computational Physics and Python Applications
- Statistical and numerical algorithms
- Plasma Diagnostics and Applications
- Spectroscopy and Chemometric Analyses
- Magnetic Properties and Applications
- Spectroscopy Techniques in Biomedical and Chemical Research
- Planetary Science and Exploration
- Characterization and Applications of Magnetic Nanoparticles
- Water Quality Monitoring and Analysis
Goddard Space Flight Center
2015-2024
Heliophysics
2014-2024
Heliophysics Science Division
2020-2023
Catholic University of America
2023
Marshall Space Flight Center
2023
Laboratory for Atmospheric and Space Physics
2023
Center for Astrophysics Harvard & Smithsonian
2023
University of Colorado Boulder
2023
University of Illinois Urbana-Champaign
2023
Southwest Research Institute
2023
We propose a new model for the initiation of solar coronal mass ejection (CME). The agrees with two properties CMEs and eruptive flares that have proved to be very difficult explain previous models: (1) low-lying magnetic field lines, down photospheric neutral line, can open toward infinity during an eruption; (2) eruption is driven solely by free energy stored in closed, sheared arcade. Consequently, closed state well above posteruption state. key feature our occur multipolar topologies...
Observational and theoretical evidence suggests that coronal heating is impulsive occurs on very small cross-field spatial scales. A single loop could contain a hundred or more individual strands are heated quasi-independently by nanoflares. It therefore an enormous undertaking to model entire active region the global corona. Three-dimensional MHD codes have inadequate resolution, one-dimensional (1D) hydrodynamic too slow simulate many thousands of elemental must be treated in reasonable...
The three-dimensional structure of solar active region NOAA 7986 observed on 1996 August 30 with the Extreme-Ultraviolet Imaging Telescope (EIT) board Solar and Heliospheric Observatory (SOHO) is analyzed. We develop a new method dynamic stereoscopy to reconstruct geometry dynamically changing loops, which allows us determine orientation mean loop plane respect line sight, prerequisite correct properly for projection effects in models. With this filter-ratio technique applied EIT 171 195 Å...
view Abstract Citations (219) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Magnetic Field of Solar Prominences Antiochos, S. K. ; Dahlburg, R. B. Klimchuk, J. A. A model is presented which accounts for the formation coronal magnetic field lines with appropriate 'dipped' structure to support prominences. critical ingredients are that prominence a truly three-dimensional significant variation along length, and strongly sheared near...
In order to test different models of coronal heating, we have investigated how the magnetic field strength flux tubes depends on end-to-end length tube. Using photospheric magnetograms from both observed and idealized active regions, computed potential, linear force-free, magnetostatic extrapolation models. For each model, then determined average strength, ⟨B⟩, in approximately 1000 individual with regularly spaced footpoints. Scatter plots ⟨B⟩ versus length, L, are characterized by a flat...
The radiative signatures of the nanoflare model for coronal heating are investigated. If an observed loop is assumed to consist many small strands that cannot be distinguished spatially by EUV or X-ray observations, we able calculate differential emission-measure profiles and filling factors a range models. In this picture undergo continual cooling, leading corona comprising with broad temperatures densities. Thus, observations over will show multithermal structure. cyclical heating-cooling...
New solar extreme-ultraviolet (EUV) irradiance observations from the NASA Solar Dynamics Observatory (SDO) EUV Variability Experiment provide full coverage in range 0.1 to 106 nm and continuously at a cadence of 10 s for spectra resolution even faster, 0.25 s, six bands. These can be decomposed into four distinct characteristics during flares. First, emissions that dominate flare's impulsive phase are transition region emissions, such as He ii 30.4 nm. Second, hot coronal above 5 MK gradual...
We highlight 10 key aspects of coronal heating that must be understood before we can consider the problem to solved. (1) All is impulsive. (2) The details matter. (3) corona filled with elemental magnetic stands. (4) densely populated current sheets. (5) strands reconnect prevent an infinite build-up stress. (6) Nanoflares repeat different frequencies. (7) What characteristic magnitude energy release? (8) causes collective behaviour responsible for loops? (9) are onset conditions (10)...
A well known behavior of EUV light curves discrete coronal loops is that the peak intensities cooler channels or spectral lines are reached at progressively later times than hotter channels. This time lag understood to be result hot loop plasma cooling through these lower respective temperatures. However, typically comprise only a minority total emission in active regions. Is this pattern common property region plasma, does it occur unique circumstances, locations, and times? The new SDO/AIA...
Abstract Hinode is Japan’s third solar mission following Hinotori (1981–1982) and Yohkoh (1991–2001): it was launched on 2006 September 22 in operation currently. carries three instruments: the Solar Optical Telescope, X-Ray EUV Imaging Spectrometer. These instruments were built under international collaboration with National Aeronautics Space Administration UK Science Technology Facilities Council, its has been contributed to by European Agency Norwegian Center. After describing satellite...
We present simulations of a model for the formation prominence condensation in coronal loop. The key idea behind is that spatial localization loop heating near chromosphere leads to catastrophic cooling corona. Using new adaptive grid code, we simulate complete growth and find after ~5000 s it reaches quasi-steady state. show size time are good agreement with data discuss implications observations prominences surrounding
view Abstract Citations (142) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Model for the Formation of Solar Prominences Antiochos, S. K. ; Klimchuk, J. A. model formation prominence condensations in hot coronal loops is proposed. Previous studies have concentrated on cooling plasma by decreasing heating rate. The difficulty with such models that when decreases, most loop mass lost draining onto chromosphere. It argued a condensation...
view Abstract Citations (148) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Soft X-Ray Loops and Coronal Heating Porter, Lisa J. ; Klimchuk, James A. We have measured the temperatures, pressures, lengths of 47 nonflaring coronal loops observed by Telescope on Yohkoh satellite. The median temperature is 5.7 x 106 K, pressure 1.6 1016 cm-3 K. carefully examined possible random systematic errors in measurements found, through simulated...
The nanoflare model of Cargill (1994a) is used to active region loops observed by the Yohkoh Soft X-ray Telescope (SXT). Using information concerning dimensions and energy-loss rate each loop, a range loop models with different temperatures, emission measures, filling factors generated. For hot (T > 4 × 106 K), it shown that less than 0.1 can fit data, although uncertainties be quite large. cool ≈ 2 cannot reproduce temperature measure for any value factor. Earlier work Porter & Klimchuk...
A number of theoretical and observational considerations suggest that coronal loops are bundles unresolved, impulsively heated strands. This "nanoflare" model, as it is sometimes called, predicts high-speed evaporative upflows, which might be revealed nonthermal broadening spectral line profiles. We have therefore generated synthetic profile observations based on one-dimensional hydrodynamic simulations for comparison with actual observations. The predicted profiles Ne VIII (770.4 Å), a...
It is largely agreed that many coronal loops—those observed at a temperature of about 1 MK—are bundles unresolved strands are heated by storms impulsive nanoflares. The nature heating in hotter loops and the very important but ignored diffuse component active regions much less clear. Are these also impulsively, or quasi-steady? spectacular new data from Atmospheric Imaging Assembly (AIA) telescopes on Solar Dynamics Observatory offer an excellent opportunity to address this question. We...
This paper develops the zero-dimensional (0D) hydrodynamic coronal loop model "Enthalpy-based Thermal Evolution of Loops" (EBTEL) proposed by Klimchuk et al (2008), which studies plasma response to evolving heating, especially impulsive heating events. The basis EBTEL is modelling mass exchange between corona and transition region chromosphere in variations, with key parameter being ratio radiation. We develop new models for this that now include gravitational stratification a physically...
The "smoking gun" of small-scale, impulsive events heating the solar corona is expected to be presence hot (>5 MK) plasma. Evidence for this has been scarce, but gradually begun accumulate due recent studies designed constrain high-temperature part emission measure distribution. However, detected component often weaker than models predict and in common modeling assumption that ionization balance remains equilibrium. launch latest generation space-based observing instrumentation on board...
The X-Ray Telescope (XRT) on the Japanese/USA/UK Hinode (Solar-B) spacecraft has detected emission from a quiescent active region core that is consistent with nanoflare heating. fluxes 10 broadband X-ray filters and filter combinations were used to construct differential measure (DEM) curves. In addition expected peak at log T = 6.3–6.5, we find high-temperature component significant > 7.0. This weak compared main peak—the DEM down by almost three orders of magnitude—which accounts fact it...