SPACS-NRL Collaborative Research Poster Session Abstracts
| Valuing Mortgage Default Option with Least Square Monte Carlo method |
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Xun Wang, James Gentle
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| The classic contingent-claims pricing model views the borrower's right to default on a mortgage as a put option. As an American type option, default option price does not have an analytical solution and can not be solved through traditional Monte Carlo method. In this research, Least square Monte Carlo (LSM) method is applied to solve the default option price by iteratively calculating the optimal exercise price through a set of least square regression equations on the expected future exercise benefits. The resulting default option prices based on a few simulated environment scenarios are shown in tables and figures. |
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| Dynamical Properties of Shuttle Plumes in the Lower Thermosphere |
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Robert Meier et al.
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| Prior to orbital injection, Space Shuttles fly nearly horizontally in the lower thermosphere for 1000 km. During the main engine burn, some 300 metric tons of water vapor are deposited between 100 and 115 km. Photodisssociation of water results in large plumes of atomic hydrogen that can expand rapidly and extend for thousands of kilometers. From 2002 to 2007, the Global Ultraviolet Imager (GUVI) on NASA’s Thermosphere Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) satellite imaged many of these hydrogen plumes while viewing in the nadir. We compare the spreading of the hydrogen plume with a two-dimensional model that includes photodissociation and molecular diffusion. Molecular diffusion appears to be sufficient to account for the expansion, although contributions from turbulent mixing cannot be excluded. We also compare the bulk motion of the observed plumes with wind climatologies derived from satellite observations. The plumes sometimes move much faster than predictions of wind climatologies, but certain dynamical processes, such as the two-day wave, can account for at least some of the high speed observations. We will present an overview of the observations and the derived time-dependent dynamical characteristics of the hydrogen plumes. |
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| A Search for Supermassive Black Holes in Bulgeless Galaxies |
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Shobita Satyapal
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| We now know that supermassive black holes lurk in the centers of most bulge-dominated galaxies in the local Universe and that their black hole mass and the stellar velocity dispersion of their host galaxy are strongly correlated. This discovery has launched numerous speculations that the formation and evolution of galaxies and supermassive black holes are fundamentally linked, perhaps as feedback from the active galactic nucleus regulates the surrounding star formation in the host galaxy. However, an important outstanding question remains unresolved: Is a bulge in general necessary for a black hole to form and grow? The answer to this question has a profound impact on some key fundamental questions on the connection between black holes and galaxy formation and evolution that have yet to be answered such as: Which forms first in a galaxy, the black hole or the bulge? What is the origin, efficiency of formation, and mass scale of supermassive black hole seeds? Are interactions necessary for black holes to form and grow? In this talk, I will give a brief overview of our research group's multiwavelength investigations into active supermassive black holes in the centers of bulgeless galaxies. |
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| Data Mining Research with the Large Synoptic Survey Telescope |
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Kirk Borne
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| The LSST catalog database will exceed 10 petabytes, comprising several hundred attributes for 5 billion galaxies, 10 billion stars, and over 1 billion variable sources (optical variables, transients, or moving objects), extracted from over 20,000 square degrees of deep imaging in 5 passbands with thorough time domain coverage: 1000 visits over the 10-year LSST survey lifetime. The opportunities are enormous for novel scientific discoveries within this rich time-domain ultra-deep multi-band survey database. Data Mining, Machine Learning, and Knowledge Discovery research opportunities with the LSST are now under study. We will describe features of the LSST science database that are amenable to scientific data mining, object classification, outlier identification, and survey science validation. |
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| Grey-Tone Lithography |
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Marc Christophersen
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| The fabrication of 3-D microstructures with well-defined curved surface contours is of great importance for various mechanical, optical and electronic devices. Complex geometrical structures or topographies are necessary to obtain a certain mechanical stability, a specific surface property or a predetermined electrostatic field configuration. Laser direct write micro-stereo-lithography, derived from conventional stereo-lithography, has been shown to be a feasible approach to create high aspect ratio and sophisticated 3-D parts. However, compared to micro-fabrication processes, stereo-lithography needs extra equipment and has a low throughput. On the other hand, micro-fabrication using "gray-scale" mask technology offers a solution that is compatible with batch processing and allows fabrication on silicon substrates. "Gray-tone" lithography in combination with RIE (Reactive Ion Etching) and DRIE (Deep Reactive Ion Etching) allows the creation of 3-D structures via a low cost, short cycle time, single exposure process. This poster presents true gray-tone lithography using simple contact lithography with an optical diffuser. The main idea is to randomize the collimated light using an optical diffuser to generate uniform, controllable intensity distributions in the photoresist. This is ideal for gray-tone lithography. |
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| Trenched Detectors |
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Marc Christophersen
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| 3-D detectors were first introduced by S. Parker et al. as radiation-hard detectors. We present 3-D detectors for use as thick gamma-ray detectors. Current room-temperature gamma-ray detectors are built in planar device architecture. We use micromachining techniques to introduce vertical electrodes, which allow lateral charge collection, decoupling thickness and charge collection properties. The ultimate goal is the ability to form cm thick gamma-ray detectors. The vertical electrodes are micro-machined trenches with depth up to 1.7 mm in silicon. We present the basic detector structure, Silvaco simulations, and first radiation measurements. An energy resolution of 2.3 keV FWHM at 59.5 keV was obtained. This is evidence of excellent charge collection from the trenches. |
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| Imaging Geospace Electrons using Thomson Scattering: A New Tool for Operational Space Weather Monitoring |
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Damien Chua, C. Englert, R. Meier, D. Socker, J. M. Picone, T. Carter, J. Huba, S. Slinker, J. Krall, and W. Vincent
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| Observing Thomson scattered, visible solar radiation provides a means to directly and globally image the electron distributions in the Earth’s ionosphere, plasmasphere, and the magnetosphere. Such observations would provide a revolutionary capability to directly observe for the first time how electron densities in the near-Earth space environment respond to forcing from the solar wind, leading to great improvements to and likely evolution of now data-starved operational space environment forecasting models. Images of Thomson scattered light have been used successfully to observe the solar electron corona and heliospheric structures such as coronal mass ejections (CMEs) and co-rotating interaction regions (CIRs). We investigate the feasibility of adapting this remote sensing technique to directly image the electrons in geospace for the first time. The brightness of Thomson scattered solar radiation from geospace is computed using line of sight electron column densities provided by the SAMI3 model of the ionosphere, coupled to the Lyon-Fedder-Mobarry (LFM) global MHD model of the magnetosphere. While the calculated Thomson scattering brightness from geospace electrons is faint compared to the expected background sources (e.g. zodiacal light, instrumental scattered light) we show that it is feasible, although challenging, to make this measurement. We present our preliminary mission concept and our proposed path toward an operational space environment monitoring system. |
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| Mass Measurements of Coronal Mass Ejections Using the SECCHI-COR2 Coronagraphs |
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Robin Colaninno, Angelos Vourlidas, and Arnaud Thernisien
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| The twin Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) COR2 coronagraphs of the Solar Terrestrial Relations Observatory (STEREO) provide images of the solar corona from two view points in the solar system. Since their launch in late 2006, the STEREO Ahead (A) and Behind (B) spacecrafts have been slowly separating from Earth at a rate of 22.5 degrees per year. By the end of 2007, the two spacecraft were separated by more than 40 degrees from each other. At this time, we began to see large-scale differences in the morphology and total intensity between coronal mass ejections (CMEs) observed with SECCHI-COR2 on STEREO-A and B. Due to the effects of the Thomson scattering geometry, the intensity of an observed CME is dependent on the angle it makes with the observed plane-of-the-sky. From the intensity images, we can calculate the integrated line of sight electron density and mass. We demonstrate that it is possible to simultaneously derive the direction and true total mass of the CME if we make the simple assumption that the same mass should be observed in COR2-A and B. |
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| The Chemistry of Irradiated Ices |
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Paul Cooper
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| The AIMIS (Astrophysical Ice and Matrix Isolation Spectroscopy) Laboratory was established in 2007 in the Department of Chemistry and Biochemistry. The laboratory’s research efforts are focused on the radiation-induced chemistry of ices relevant to planetary bodies, comets and interstellar grains. The scope of this work ranges from researching the reactions and reactivity of radicals and radical-complexes, to comparing spectral data with astronomical observations, to the very broad discipline of astrobiology. This poster will highlight the recent and ongoing research activities within the lab. |
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| High Energy Radiations from Space |
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Charles D. Dermer, Justin Finke, and Soebur Razzaque
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| Data from high-energy space radiation detectors built with NASA and NRL support is modeled and interpreted. The launch of the Fermi Gamma ray Space Telescope opens the GeV window. Coupled with the rapid activity in ground-based gamma-ray, neutrino, and cosmic ray observatories and balloon-borne neutrino telescopes, high-energy space science enters a new era to understand (1) The origin of the Cosmic Rays (2) High-energy neutrino sources (3) Jets from Black Holes (4) Gamma ray bursts (5) The spectrum and intensity of extragalactic background light. |
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| Type III-L Solar Radio Bursts and their Associations with Solar Energetic Proton Events |
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Robert Duffin, Stephen M. White, Paul S. Ray, and Michael L. Kaiser
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| Type III-L bursts are a sub-class of type III solar radio bursts that tend to occur after the impulsive phase of flares; are longer in duration than individual type IIIs and tend to be low-frequency. There has been a proposal that type III-Ls are connected to solar energetic proton (SEP) events. Most work on this connection has started from samples of SEP events, but if type III-Ls are to be useful for prediction of SEP events, then we need to understand the properties of samples of type III-L bursts. This talk reports preliminary results from such a study. An operating definition based on previous work is used to identify type III-L events amongst M- and X-class flares from 2001; and then associations with other properties of these events are investigated, including association with SEP events. If there is an association with SEP events, one important factor that these bursts allow us to address is the question of whether acceleration takes place at an associated CME, or closer to the flare site well below the CME. |
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| Surface Alfvén Wave Damping in a 3D Simulation of the Solar Wind |
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Rebekah Evans, Merav Opher, V. Jatenco-Pereira, and T. I. Gombosi
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| It is known that a source of additional momentum is needed to drive the solar wind. Here we investigate the effect of surface Alfvén wave damping in solar minima conditions. The surface Alfvén wave damping length L depends on the superradial expansion factor S of magnetic field lines. We calculate S for Carrington Rotation 1912 with steady state solar background generated with the Space Weather Modeling Framework and compare with estimates by Dobrzycka et al. 1999 using SOHO observations. We estimate the surface Alfvén wave damping for active regions, quiet sun, and the border between open and closed magnetic field lines. We address how our results can be incorporated in a MHD thermally driven-wind model. |
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| The Chandra view of NGC3621: A Bulgeless Galaxy Hosting an AGN |
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Mario Gliozzi, Shobita Satyapal, and M. Eracleous
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| We present the preliminary results from our Chandra investigation of the nearby bulgeless galaxy NGC3621. This object, which is optically classified as a normal galaxy, has recently been discovered by Spitzer mid-IR spectroscopy to contain a buried AGN. The unique capabilities of Chandra are used to disentangle the different components contributing to the X-ray emission and to perform spatially-resolved spectroscopy. The Chandra observation has indeed detected a weak X-ray source at the center of the galaxy, apparently confirming the presence of a buried AGN. Interestingly, Chandra has also revealed the presence of two bright sources located almost symmetrically at 20" from the center. |
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| The Fermi Gamma Ray Space Telescope |
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J. Eric Grove and W. Neil Johnson
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| The Fermi Gamma-Ray Space Telescope, formerly known as GLAST, is a mission to measure the cosmic gamma-ray flux in the energy range 20 MeV to >300 GeV, with supporting measurements for gamma-ray bursts from 8 keV to 30 MeV. The very large field of view makes it possible to observe 20% of the sky at any instant, and the entire sky on a timescale of a few hours. With its successful launch in June 2008, Fermi has opened a new and important window on a wide variety of phenomena, including black holes and active galactic nuclei, the optical-UV extragalactic background light, gamma-ray bursts, the origin of cosmic rays and supernova remnants, and searches for hypothetical new phenomena such as supersymmetric dark matter annihilations and Lorentz invariance violation. In addition to the science opportunities, this poster includes a description of the instruments, the opportunities for guest observers, students and postdocs, and the mission status. |
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| The SoftWare for the Optimization of Radiation Detectors (SWORD) |
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Chul Gwon
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| The SoftWare for the Optimization of Radiation Detectors (SWORD is an integrated system (based on MCNPX and GEANT4 3D Monte Carlo radiation transport codes) useful for the optimization of high energy radiation detection systems. A set of usable sample inputs and analysis algorithms are integrated into the system. Sample inputs include Special Nuclear Material (SNM) targets, nuisance sources, and industrial and marine backgrounds. Analysis algorithms include spectroscopy and imaging for coded aperture detectors, Compton imagers and fast neutron imagers. The system is designed from the start to be easy to use and to be deployable to detector design and system architecture study groups who are its ultimate users. Work with the SWORD team involves computer modeling of physical phenomena, developing code in C++ for the front-end system, and analyzing spectra from various sources. This project is funded by the Domestic Nuclear Detection Office of the Department of Homeland Security. |
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| Ulysses Observations of Periodic Structures in the Solar Wind |
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Christina Henderson and Robert Weigel
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| Knowledge of the presence and evolution of periodicities in the solar wind at out-of-ecliptic latitudes can give information about the latitudinal structure of the solar wind and help distinguish between theories that predict the global characteristics of the solar wind and heliosheet. We have computed the spectrogram of the plasma velocity measured by the Ulysses spacecraft in the interval of 1991-2008 in the range of 5-and 40-days and confirmed periodicities observed in previous limited-time-interval studies. A statistical method has been developed to determine if the observed periodicities are due to physical effects such as current sheet crossings or multiple coronal holes as opposed to being harmonics of a fundamental. Based on those criteria, we conclude that many non-26-day are due to physical processes and not simply harmonics of the 26-day period. An example occurs in late 1999 when Ulysses was at mid-latitudes; a clear 13-day period is present without an accompanying26-day period. The spectrogram also reveals 14-, 23-, and 30-35-day periods during solar minimum while Ulysses was at high southern latitudes which is consistent with a highly warped and structured current sheet at high latitudes during solar minimum. This feature appears for both solar cycles 22 and 23, although the periods are slightly shorter during the solar cycle 23 southern polar pass. We also note complexity in the periods that appear during the solar cycle 23 maximum. All of these features are interpreted in the context of warped current sheets and other periodically appearing structures. |
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| The Mid-Infrared Properties of Star Forming Dwarf Galaxies |
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Sukbum Hong, Jessica L. Rosenberg, Matthew L. N. Ashby, and John J. Salzer
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| We present a study of star-forming dwarf galaxies using mid-infrared observations from Spitzer Space Telescope as a probe of star formation. This sample represents the first large mid-infrared study of star-forming dwarf galaxies. Preliminary results show the star forming dwarf galaxies span a wide range of mid-infrared color with the most metal-rich systems having reddest colors. We also confirm that the mid-infrared color is more correlated with the star formation rate than it is with the metallicity as was previously shown for a smaller sample. We estimate the PAH emission in these galaxies and compare it with the galaxies’ metallicity, star formation rate, and mid-infrared color. We show that the PAH emission is strongly correlated with mid-infrared color and the metallicity. However, the star formation rate is not correlated with the PAH emission. |
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| Uncovering AGNs Missed by Optical Surveys in Late-Type Galaxies |
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Marla Katz, Shobita Satyapal, and Mario Gliozzi
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| The vast majority of currently known active galactic nuclei (AGN) in the local Universe reside in host galaxies with prominent bulges, leading to the general consensus that black hole formation and growth is fundamentally connected to the build-up of galaxy bulges. However, recent mid-infrared spectroscopic studies using Spitzer of a sample of optically "normal" late-type galaxies reveal remarkably the presence of high-ionization [NeV] lines in several sources, providing strong evidence for AGNs in these galaxies. We present follow-up X-ray observations recently obtained with XMM-Newton of two such sources, the late-type optically normal galaxies NGC 4536 and NGC 3367. Both sources are detected in our observations. Detailed spectral analysis suggests that they are both consistent with AGN. These observations are used to estimate the AGN luminosity and place constraints on the black hole mass in these galaxies. |
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| Self Organization in a Diffusion Model of Thin Electric Current Sheets |
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Andrew Kercher and Robert Weigel
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| In space plasmas thin electric current sheets are observed to form near the surface of the sun, in the solar wind, and in Earth's magnetotail. The basic physics of this system can be approximated by a diffusion model with a diffusivity that has hysteresis and switches between low and high, depending on local current amplitude. We show that under constant energy input conditions, this system evolves to a state with characteristics of self-organized criticality. |
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| Comparison of Flux-Rope CME Model and SECCHI Data |
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Valbona Kunkel and James Chen
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| We use the new SECCHI data to test the erupting flux rope model. This model (Chen 1996) has been shown to be able to replicate observed CME dynamics in the LASCO field of view but has not been directly compared with data beyond 30 Rs. we discuss new SECCHI observations of CMEs and their dynamics and extend the modeling of CME propagation to HI1 field of view, out to about 100 Rs. Four CMEs are discussed. It is shown that the erupting flux rope model fits the observed height-time and velocity-time data throughout the EUVI-COR1-COR2-HI1 field of view. This suggests that the model correctly captures the important dynamics of CMEs, i.e., the forces acting on CMEs. However, we have found that in order to fit the CME data both within 30 Rs and beyond 30 Rs, the CME interaction with the ambient medium needs better treatment than it was originally given. Accordingly, we have improved the calculation of the drag force. Previously, the centroid speed was used to calculate the speed differentials. However, it is the leading-edge (LE) surface that displaced the ambient plasma. We have incorporated the LE surface area and the LE speed in the drag calculation. While the difference from the previous calculations is relatively small so that it does not have a major impact within the COR1 and COR2 FOV, it can significantly affect the long-time propagation out to 100 Rs. Thus, the extended field of view SECCHI imposes stronger constraints on the model than the previous data set (2-30 Rs). |
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| Magnetic Reconnection and Flare Loop Formation in Solar Eruptions |
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Mark G. Linton
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| Solar eruptions are sudden ejections of coronal plasma and magnetic field into the interplanetary medium, accompanied by large flares in the solar atmosphere. These events are the most dynamic phenomena in the solar corona and are important drivers of space weather through particle acceleration, flare-induced coronal heating, and the interaction of the ejecta with the Earth's magnetosphere. Magnetic reconnection is believed to be the key driver of these eruptions and their associated flares, and recently the combination of high resolution solar observations and high performance computing has allowed us to make breakthroughs in understanding how this reconnection proceeds. I will present simulations of the coronal reconnection and flaring which occur behind these eruptions, focusing on localized, three dimensional reconnection in a post-eruption current sheet. I will show how the resulting reconnected fields can form evacuated coronal downflows, hot arcades of post-eruption loops, and photospheric ribbons of H-alpha flare emission, as observed by solar missions such as SOHO, TRACE, STEREO and Hinode. I will then discuss the implications of this work for the creation of plasmoids via reconnection in the Earth's magnetotail current sheet. |
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| Mobile Imaging and Spectroscopic Threat Identification (MISTI) |
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Lee J. Mitchell, Bernard F. Phlips, W. Neil Johnson, Robert Roberts, Eric A. Wulf, C. J. “Kim” Lister, Daniel Taibi, Kelia D. Bynum, Byron E. Leas, Gerald Guadagno, and Thomas Pickard
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| Characteristic gamma-radiation can be used to identify radiological threats, however gamma-ray detection and imaging is extremely difficult due to the low interaction probability and inability to focus high energy photons. MISTI’s hybrid system combines the exceptional spectroscopic capabilities of germanium with the cost effective collection power of a large volume sodium iodide imaging array. The system is a mobile, self contained, gamma-ray spectroscopy and imaging system for detecting radiological threats. While moving, the MISTI system is designed to detect sources of nuclear materials, such as a 1mCi Cs-137 source at distances up to 100m in 20s. The spectroscopic identification is performed using a 28 detector germanium array, which in turn triggers imaging using a 10x10 sodium iodide array, when a source is detected. The project is composed of commercial off the shelf technology, allowing a quicker transition from the design phase to the construction phase, reducing total cost. The data from the sensor will be analyzed in real time on board the vehicle and is combined with images and data from other instruments to provide the users with a visual location of the source. MISTI’s unique design reduces false alarms, while improving weak source location and identification in urban and rural environments. |
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| Sky Mining with Virtual Observatories |
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Pragyansmita Nayak and Kirk Borne
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| Astronomy-based data mining (or Sky Mining) is a reality today in spite of the multitude and disparate types of data. It has largely been made possible by the easy access and manipulation of the measured and simulated data using VO (Virtual Observatory) tools. Similar to other domains, astronomy-based data and manipulation results are handled in XML format. For example, VOTable is the specific XML format for the exchange of VO data tables. The VO Registry provides a simple Google-like interface to search for data collections and catalogs of interest. A search for quasars returns 228 results today and this includes catalogs, images, cone search services, data-retrieval services, and publications along with metadata about each of these search results. The results can easily be filtered based on what the user needs. VO Inventory, VIM (VO Integration and Mining), and Datascope tools help the user find datasets that contain information relevant to a certain position in the sky and perform further analysis on the results found by combining related data from multiple sources. Various paths exist for the flow of data through these and other available VO tools. A categorization of the available VO tools and some of the possible data-flows to facilitate sky mining will be presented as part of this poster presentation. In addition, we illustrate this distributed data mining approach with a scientific example: estimating photometric redshifts of quasars using distributed multi-wavelength data. |
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| A Catalogue of Automated Detected CMEs |
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Oscar Olmedo and Jie Zhang
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| A Solar Eruptive Event Detection System (SEEDS) has been developed to automatically detect, track, and catalog Coronal Mass Ejections (CMEs) with SOHO and STEREO corona observations. The method developed is based on decomposing 2-D Coronagraph images to 1-D and looking for outstanding bright regions. Thresholds determine these regions, and in time sequences, CMEs can be located and tracked. A complete catalog of CMEs using LASCO C2 coronagraphs has been compiled using the SEEDS software and the results are made available online (http://spaceweather.gmu.edu/seeds). A preliminary catalog has been made using SECCHI COR2 coronagraphs and is also available online. We have been experimenting with real-time detection and make these results available online on a daily basis. We present statistics comparing the detections made with LASCO C2 with the CDAW CME catalog for the whole solar cycle 23. It is found that SEEDS is able to identify approximately 75% of the CMEs found within the CDAW CME catalog (omitting CMEs with quality index of 0 indicating an ill-defined CME). |
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| What Do CME-Shocks Look Like?: Study of Shock Geometry |
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Veronica Ontiveros and Angelos Vourlidas
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| We use ray tracing software to simulate white light coronagraph images of common 3D shock-like geometries, i.e. spherical and bow-shock type. We obtain the density profiles for different projections, shock thickness, and background and upstream densities. The results are compared to density profiles obtained from analyzing LASCO coronagraph images of CMEs that are good candidates to drive a shock due to their high velocities (V>1500 km/s). |
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| 3D Numerical Simulation and Stereoscopic Observations of Coronal Jets |
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Etienne Pariat
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Recent X-ray solar observations made by XRT/Hinode have revealed that coronal jets are more frequent phenomena than previously believed. It is widely accepted that magnetic reconnection is the fundamental mechanism that gives rise to the jets (Shibata 00). The improved spatial and temporal resolution of the STEREO observations in combination with stereoscopy yields new insights into the origins of coronal jets, and provides detailed data that can be used to test and refine models.
We present the results of 3D numerical simulations of our model for coronal jets (Pariat et al. 09). The simulations were performed with our state-of-art MHD solver ARMS (Adaptively Refined MHD solver)}, a 3D flux-corrected transport magnetohydrodynamic code using adaptive meshes. The basic idea of the model is that a jet is due to the release of twist as a closed field region undergoes interchange reconnection with surrounding open field. The photospheric driven evolution of the structure results in the generation of a non linear Alfv\'en wave along the open fields. Using stereoscopic EUVI images, we reveal the presence of such twisted structure in a coronal jet event. |
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| SECCHI Observations of EIT Waves |
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Spiros Patsourakos, Angelos Vourlidas, Guillermo Stenborg, Arnaud Thernisien, and Yi-Ming Wang
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| More than a decade after their discovery by EIT, EUV waves look more mysterious than ever with conflicting interpretations of their origin been proposed and debated. Part of the problem should be attributed to the limitations of EIT observations almost exclusively used in the study of these waves: low temporal cadence, single-temperature and viewpoint coverage. The situation dramatically improved when data from the twin STEREO spacecraft started to become available. These observations provide improvements in 3 important areas: higher image cadence (up to x10), multi-temperature (0.08-2 MK), almost simultaneous coverage and multiple viewpoint observations. We will show how all these unique elements of STEREO observations, and particular their 3D aspect, can place new and important constraints on the mechanisms responsible for EUV waves. |
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| Curved Detectors |
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Bernard Phlips
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| As vertex detectors for smaller for smaller inner beam pipe diameters are required, the planar nature of the detector becomes more and more of a problem. We present a curved silicon vertex detector, whose radius of curvature can be adjusted to the beam pipe. The advantage of these curved detectors over conventional planar ones is twofold: The first advantage is that these detectors are curved to a specific curvature and shaped directly for the specific application (e.g. beam pipe radius), and second, the curvature of the backside is independent from the front surface, which allows thinning of the detector using standard semiconductor processing. Both strip detectors and pixel arrays have been realized on the curved topography. The key micro-fabrication technique for curved topography, so called "gray-tone lithography", will be introduced and discussed. We demonstrated low-noise performance by successfully detecting low-energy gamma-ray with a curved strip and pixel detector. |
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| What are the Differences Between Confined and Eruptive Flares? |
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Watanachak Poomvises, Jie Zhang, and Yuming Wang
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| Solar flares are caused by impulsive and large energy release in the corona, presumably through the fast magnetic reconnection resulting in efficient particle acceleration and strong heating. It has been found that about 90% of X-class flares are associated with coronal mass ejections (CMEs), which involve the transformation and ejection of a large scale coronal magnetic structure. About 50% of the less energetic M-class flares are associated with CMEs, and even a smaller percentage for C-class and weaker flares. The question is why some flares are eruptive (associated with CMEs), and some other flares are confined (energy release without large scale ejection). We have made a preliminary study on all X-class, 124 in total, and M-class flares, 1427 in total, from 1996-2005. For each of these flares, based on a combination of NOAA/SEC flare report and SOHO EIT and LASCO observations, we identify its surface source region and then determine its eruptiveness. We then carefully analyze the magnetic properties of the source regions of the two types of flares. For the efficiency of mass processing, we use the MDI Carrington synoptic charts instead of individual magnetogram images. For each source region, we extract a set of parameters, including the distance between flare location and the center of mass (COM) of the magnetic field distribution, total flux, length of neutral lines etc. This study will help understand the flare eruptiveness. Further, such a comprehensive statistical study may yield useful empirical relation to predict the flare eruption based on the source region properties, which is useful for forecasting space weather. |
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| First STEREO Observation of a Quiet Sun CME |
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Eva Robbrecht, Spiros Patsourakos, and Angelos Vourlidas
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| Streamer-blowouts form a particular class of CMEs characterized by a slow rise and swelling of the streamer that can last for days. While they are more massive than the average CME, their slow development complicates their association with features/activity in the low corona and hampers studies on their initiation mechanism(s). This paper reports on the first observation from 2 viewpoints of a streamer blowout CME. The event was observed by the SECCHI/COR2 A instrument as a typical flux-rope type CME, while a very faint partial halo was observed in COR2-B. The CME erupts from the east limb in the COR2 A field of view. EUVI-171 A images show a bright feature above the limb, traveling from the southern hemisphere towards the equator after which it rises into the coronagraphic fields of view developing into the flux-rope structure CME. At the time of eruption the separation between the two STEREO spacecraft is sufficiently large (54 deg) to observe the source region face-on in STEREO-B. However, inspection of EUVI B data didn't reveal any particular source region, other than the quiet sun. No flaring activity could be related to the eruption. This observation shows unambiguously that a CME eruption does not necessarily have a clear on-disk signature. It also sheds light on the long-standing question of the necessity of having a flare for producing a CME. This result supplies strong constraints for CME initiation models. This type of observation could not have been achieved without the multi-viewpoint capabilities of STEREO. |
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| New Perspectives on the Thermosphere and Ionosphere from the RAIDS Experiment on the ISS |
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Andrew W. Stephan, Scott A. Budzien, Paul R. Straus, Andrew B. Christensen, Rebecca L. Bishop, and James H. Hecht
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| The Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of three photometers, three spectrometers, and two spectrographs that is manifested to fly on the Japanese Experiment Module-Exposed Facility aboard the International Space Station (ISS) in 2009. The RAIDS experiment measures many airglow features across the wavelength range 50-874 nm important for remote sensing of the thermosphere and ionosphere. The primary scientific objectives of the RAIDS experiment are to study the temperature of the lower thermosphere (100–200 km), to measure composition and chemistry of the lower thermosphere and ionosphere, and to develop capabilities to monitor the dayside ionosphere via the OII 83.4 nm emission. We will present an overview of the combination of measurements RAIDS will make to provide a new perspective on the thermosphere-ionosphere system, new techniques for thermospheric-ionospheric remote sensing, and a new vantage point from the ISS to add to the growing collection of data for more robust volumetric thermospheric specification. |
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| Timing and Spectral Study of Compact Objects: Applications to Mass-Radius of Neutron Stars and Black Hole Mass Determination |
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Lev Titarchuk
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| A new method for evaluation of the Black Hole (BH) mass using this observable index-QPO frequency correlation is demonstrated. In the soft state this index-QPO frequency correlations show the saturation to the photon index at high values of the low frequency which was identified as a black hole signature. The K? line iron emission with redskewed features in CV GK Per indicates that the red skewness of the line cannot be a BH particular signature related to the redshift effects of General Relativity (GR). If the mechanism of the K? line formation is the same in CVs, NSs and BHs then it is evident that the GR effects would be ruled out as a cause of red skewness of the iron line. |
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| Coronal Loops, the Building Blocks of the Solar Atmosphere: New Insights from HINODE |
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Ignacio Ugarte Urra
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| The outer Solar atmosphere, so-called corona, is made of plasma mysteriously heated to million degree temperatures. In an environment dominated by magnetic forces, this plasma is organized in arched tubular structures anchored at the Solar surface. Called coronal loops, they are the building blocks of the atmosphere. Their properties, while not well understood, are crucial to the characterization of the elusive heating mechanism that makes them exist. The recently launched HINODE satellite, a Japanese mission in collaboration with the US and UK equipped with state-of-the-art instruments to study the magnetic and plasma properties of the Solar atmosphere, is providing unprecedented detailed measurements of the properties of coronal loops. |
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| Thermal Flipping of Interstellar Grains |
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Joe Weingartner
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| In interstellar dust grains, internal processes dissipate rotational kinetic energy. The dissipation is accompanied by thermal fluctuations, which transfer energy from the vibrational modes to rotation. Together, these processes are known as internal relaxation. For the past several years, internal relaxation has been thought to give rise to thermal flipping, with profound consequences for grain alignment theory. I show that thermal flipping is not possible in the limit that the inertia tensor does not vary with time. |
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