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Articles 1 - 30 of 231
Full-Text Articles in Physical Sciences and Mathematics
Cross-Disciplinary Learning Index: A Quantitative Measure Of Cross-Disciplinary Learning About Energy, Todd Haskell, Emily Borda, Andrew Boudreaux
Cross-Disciplinary Learning Index: A Quantitative Measure Of Cross-Disciplinary Learning About Energy, Todd Haskell, Emily Borda, Andrew Boudreaux
Physics & Astronomy
The structure of many science programs at the college level assumes that students are able to draw on and integrate ideas from multiple disciplinary contexts. However, most assessment tools focus on learning in the context of a single discipline. We describe the development and validation of an instrument to measure how well students are able to combine energy ideas from different disciplines into a coherent understanding of a phenomenon. The final version of the instrument consists of a pair of multiple-choice online assessments, along with a metric calculated from the assessment scores: the cross disciplinary learning index (CDLI). The items …
Physics Inventory Of Quantitative Literacy: A Tool For Assessing Mathematical Reasoning In Introductory Physics, Suzanne W. Brahmia, Alexis Olsho, Trevor I. Smith, Andrew Boudreaux, Philip Eaton, Charlotte Zimmerman
Physics Inventory Of Quantitative Literacy: A Tool For Assessing Mathematical Reasoning In Introductory Physics, Suzanne W. Brahmia, Alexis Olsho, Trevor I. Smith, Andrew Boudreaux, Philip Eaton, Charlotte Zimmerman
Physics & Astronomy
One desired outcome of introductory physics instruction is that students will develop facility with reasoning quantitatively about physical phenomena. Little research has been done regarding how students develop the algebraic concepts and skills involved in reasoning productively about physics quantities, which is different from either understanding of physics concepts or problem-solving abilities. We introduce the Physics Inventory of Quantitative Literacy (PIQL) as a tool for measuring Quantitative Literacy, a foundation of mathematical reasoning, in the context of introductory physics. We present the development of the PIQL and evidence of its validity for use in calculus-based introductory physics courses. Unlike …
How Curriculum Developers Cognitive Theories Influence Curriculum Development, Andrew Boudreaux, Andy Elby
How Curriculum Developers Cognitive Theories Influence Curriculum Development, Andrew Boudreaux, Andy Elby
Physics & Astronomy
[This paper is part of the Focused Collection on Curriculum Development: Theory into Design.] When we examined student responses to questions about the direction of the static friction force in various situations, we both had strong ideas about how to write a tutorial to promote deeper understanding. But our ideas were quite different. In this theoretical paper, we present the two contrasting tutorials and show how their differences can be traced to different theoretical orientations toward cognition and learning. We do not claim that one tutorial—or the theoretical framework loosely associated with it—is superior. Instead, we hope to illustrate two …
Designing Research-Based Instructional Materials That Leverage Dual-Process Theories Of Reasoning: Insights From Testing One Specific, Theory-Driven Intervention, Mila Kryjevskaia, Mackenzie R. Stetzer, Beth A. Lindsey, Alistair Mcinerny, Paula R. L. Heron, Andrew Boudreaux
Designing Research-Based Instructional Materials That Leverage Dual-Process Theories Of Reasoning: Insights From Testing One Specific, Theory-Driven Intervention, Mila Kryjevskaia, Mackenzie R. Stetzer, Beth A. Lindsey, Alistair Mcinerny, Paula R. L. Heron, Andrew Boudreaux
Physics & Astronomy
[This paper is part of the Focused Collection on Curriculum Development: Theory into Design.] Research in physics education has contributed substantively to improvements in the learning and teaching of university physics by informing the development of research-based instructional materials for physics courses. Reports on the design of these materials have tended to focus on overall improvements in student performance, while the role of theory in informing the development, refinement, and assessment of the materials is often not clearly articulated. In this article, we illustrate how dual-process theories of reasoning and decision making have guided the ongoing development, testing, and analysis …
Toward A Framework For The Natures Of Proportional Reasoning In Introductory Physics, Andrew Boudreaux, Stephen E. Kanim, Alexis Olsho, Suzanne W. Brahmia, Charlotte Zimmerman, Trevor I. Smith
Toward A Framework For The Natures Of Proportional Reasoning In Introductory Physics, Andrew Boudreaux, Stephen E. Kanim, Alexis Olsho, Suzanne W. Brahmia, Charlotte Zimmerman, Trevor I. Smith
Physics & Astronomy
We present a set of modes of reasoning about ratio and proportion as a means of operationalizing expert practice in physics. These modes, or natures of proportional reasoning, stem from consideration of how physicists reason in context and are informed by prior work in physics and mathematics education. We frame the natures as the core of an emerging framework for proportional reasoning in introductory physics, that will categorize the uses of proportional reasoning in introductory physics contexts, and provide guidance for the development of reliable assessments. We share results from preliminary assessment items indicating that university physics students have difficulty …
Framework For The Natures Of Negativity In Introductory Physics, Suzanne W. Brahmia, Alexis Olsho, Trevor I. Smith, Andrew Boudreaux
Framework For The Natures Of Negativity In Introductory Physics, Suzanne W. Brahmia, Alexis Olsho, Trevor I. Smith, Andrew Boudreaux
Physics & Astronomy
Mathematical reasoning skills are a desired outcome of many introductory physics courses, particularly calculus-based physics courses. Novices can struggle to understand the many roles signed numbers play in physics contexts, and recent evidence shows that unresolved struggle can carry over to subsequent physics courses. Positive and negative quantities are ubiquitous in physics, and the sign carries important and varied meanings. The mathematics education research literature documents the cognitive challenge of conceptualizing negative numbers as mathematical objects—both for experts, historically, and for novices as they learn. We contribute to the small but growing body of research in physics contexts that examines …
2d Ion Temperature Maps From Twins Ena Data: Idl Scripts, Amy Keesee, Earl Scime, Anna Zaniewski, Roxanne Katus
2d Ion Temperature Maps From Twins Ena Data: Idl Scripts, Amy Keesee, Earl Scime, Anna Zaniewski, Roxanne Katus
Physics & Astronomy
Energetic neutral atom (ENA) flux from the NASA TWINS mission (and previously the MENA instrument on the NASA IMAGE mission) is projected along the line of sight to the equatorial plane in GSM coordinates. A Maxwellian fit is used to calculate the ion temperature in each equatorial plane bin, creating 2D maps of ion temperatures. The files are IDL .pro scripts that can be read using a text editor. IDL software is required to run. The primary script is twins_master.pro. The scripts call other scripts that were developed by the TWINS mission team as well as publicly available IDL libraries …
The Velocity Dispersion Function Of Very Massive Galaxy Clusters: Abell 2029 And Coma, Jubee Sohn, Margaret J. Geller, H. Jabran Zahid, Daniel G. Fabricant, Antonaldo Diaferio, Kenneth J. Rines
The Velocity Dispersion Function Of Very Massive Galaxy Clusters: Abell 2029 And Coma, Jubee Sohn, Margaret J. Geller, H. Jabran Zahid, Daniel G. Fabricant, Antonaldo Diaferio, Kenneth J. Rines
Physics & Astronomy
Based on an extensive redshift survey for galaxy clusters Abell 2029 and Coma, we measure the luminosity functions (LFs) and stellar mass functions (SMFs) for the entire cluster member galaxies. Most importantly, we measure the velocity dispersion functions (VDFs) for quiescent members. The MMT/Hectospec redshift survey for galaxies in A2029 identifies 982 spectroscopic members; for 838 members, we derive the central velocity dispersion from the spectroscopy. Coma is the only other cluster surveyed as densely. The LFs, SMFs, and VDFs for A2029 and Coma are essentially identical. The SMFs of the clusters are consistent with simulations. The A2029 and Coma …
Most Observations Of Our Nearest Neighbor: Flares On Proxima Centauri, James R. A. Davenport, David M. Kipping, Dimitar Sasselov, Jaymie M. Matthews, Chris Cameron
Most Observations Of Our Nearest Neighbor: Flares On Proxima Centauri, James R. A. Davenport, David M. Kipping, Dimitar Sasselov, Jaymie M. Matthews, Chris Cameron
Physics & Astronomy
We present a study of white-light flares from the active M5.5 dwarf Proxima Centauri using the Canadian microsatellite Microvariability and Oscillations of STars. Using 37.6 days of monitoring data from 2014 to 2015, we have detected 66 individual flare events, the largest number of white-light flares observed to date on Proxima Cen. Flare energies in our sample range from 1029 to 1031.5erg. The flare rate is lower than that of other classic flare stars of a similar spectral type, such as UV Ceti, which may indicate Proxima Cen had a higher flare rate in its youth. …
The Kepler Catalog Of Stellar Flares, James R. A. Davenport
The Kepler Catalog Of Stellar Flares, James R. A. Davenport
Physics & Astronomy
A homogeneous search for stellar flares has been performed using every available Kepler light curve. An iterative light curve de-trending approach was used to filter out both astrophysical and systematic variability to detect flares. The flare recovery completeness has also been computed throughout each light curve using artificial flare injection tests, and the tools for this work have been made publicly available. The final sample contains 851,168 candidate flare events recovered above the 68% completeness threshold, which were detected from 4041 stars, or 1.9% of the stars in the Kepler database. The average flare energy detected is ~1035 erg. …
The Time-Domain Spectroscopic Survey: Understanding The Optically Variable Sky With Sequels In Sdss-Iii, John J. Ruan, Scott F. Anderson, Paul J. Green, Eric Morganson, Michael Eracleous, Adam D. Myers, Carles Badenes, Matthew A. Bershady, William N. Brandt, Kenneth C. Chambers, James R. A. Davenport, Kyle S. Dawson, Heather Flewelling, Timothy M. Heckman, Jedidah C. Isler, Nick Kaiser, Jean-Paul Kneib, Chelsea L. Macleod, Isabelle Paris, Nicholas P. Ross, Jessie C. Runnoe, Edward F. Schlafly, Sarah J. Schmidt, Donald P. Schneider, Axel D. Schwope, Yue Shen, Keivan G. Stassum, Paula Szkody, Christoper Z. Waters, Donald G. York
The Time-Domain Spectroscopic Survey: Understanding The Optically Variable Sky With Sequels In Sdss-Iii, John J. Ruan, Scott F. Anderson, Paul J. Green, Eric Morganson, Michael Eracleous, Adam D. Myers, Carles Badenes, Matthew A. Bershady, William N. Brandt, Kenneth C. Chambers, James R. A. Davenport, Kyle S. Dawson, Heather Flewelling, Timothy M. Heckman, Jedidah C. Isler, Nick Kaiser, Jean-Paul Kneib, Chelsea L. Macleod, Isabelle Paris, Nicholas P. Ross, Jessie C. Runnoe, Edward F. Schlafly, Sarah J. Schmidt, Donald P. Schneider, Axel D. Schwope, Yue Shen, Keivan G. Stassum, Paula Szkody, Christoper Z. Waters, Donald G. York
Physics & Astronomy
The Time-Domain Spectroscopic Survey (TDSS) is an SDSS-IV eBOSS subproject primarily aimed at obtaining identification spectra of ~220,000 optically variable objects systematically selected from SDSS/Pan-STARRS1 multi-epoch imaging. We present a preview of the science enabled by TDSS, based on TDSS spectra taken over ~320 deg2 of sky as part of the SEQUELS survey in SDSS-III, which is in part a pilot survey for eBOSS in SDSS-IV. Using the 15,746 TDSS-selected single-epoch spectra of photometrically variable objects in SEQUELS, we determine the demographics of our variability-selected sample and investigate the unique spectral characteristics inherent in samples selected by variability. We …
Examining The Relationships Between Colour, Teff, And [M/H] For Apogee K And M Dwarfs, Sarah J. Schmidt, Erika L. Wagoner, Jennifer A. Johnson, James R. A. Davenport, Keivan G. Stassun, Diogo Souto, Jian Ge
Examining The Relationships Between Colour, Teff, And [M/H] For Apogee K And M Dwarfs, Sarah J. Schmidt, Erika L. Wagoner, Jennifer A. Johnson, James R. A. Davenport, Keivan G. Stassun, Diogo Souto, Jian Ge
Physics & Astronomy
We present the effective temperatures (Teff), metallicities, and colours in Sloan Digital Sky Survey (SDSS), Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer filters, of a sample of 3834 late-K and early-M dwarfs selected from the SDSS Apache Point Observatory Galactic Evolution Experiment (APOGEE) spectroscopic survey ASPCAP (APOGEE Stellar Parameters and Chemical Abundances Pipeline) catalogue. We confirm that ASPCAP Teff values between 3550 < Teff < 4200 K are accurate to ∼100 K compared to interferometric Teff values. In that same Teff range, ASPCAP metallicities are accurate to 0.18 dex between −1.0 <[M/H]g − r is not a good indicator of metallicity for near-solar metallicity early-M dwarfs. We confirm that J − KS colour is strongly dependent on metallicity, and find that W1 − W2 colour is a promising …
The Muscles Treasure Survey. I. Motivation And Overview, Kevin France, R. O. Parke Loyd, Allison Youngblood, Alexander Brown, P. Christian Schneider, Suzanne L. Hawley, Cynthia S. Froning, Jeffrey L. Linsky, Aki Roberge, Andrea P. Buccino, James R. A. Davenport, Juan M. Fontenla, Lisa Kaltenegger, Adam F. Kowalski, Pablo J. D. Mauas, Yamila Miguel, Seth Redfield, Sarah Rugheimer, Feng Tian, Mariela C. Vieytes, Lucianne M. Walkowicz, Kolby L. Weisenburger
The Muscles Treasure Survey. I. Motivation And Overview, Kevin France, R. O. Parke Loyd, Allison Youngblood, Alexander Brown, P. Christian Schneider, Suzanne L. Hawley, Cynthia S. Froning, Jeffrey L. Linsky, Aki Roberge, Andrea P. Buccino, James R. A. Davenport, Juan M. Fontenla, Lisa Kaltenegger, Adam F. Kowalski, Pablo J. D. Mauas, Yamila Miguel, Seth Redfield, Sarah Rugheimer, Feng Tian, Mariela C. Vieytes, Lucianne M. Walkowicz, Kolby L. Weisenburger
Physics & Astronomy
Ground- and space-based planet searches employing radial velocity techniques and transit photometry have detected thousands of planet-hosting stars in the Milky Way. With so many planets discovered, the next step toward identifying potentially habitable planets is atmospheric characterization. While the Sun–Earth system provides a good framework for understanding the atmospheric chemistry of Earth-like planets around solar-type stars, the observational and theoretical constraints on the atmospheres of rocky planets in the habitable zones (HZs) around low-mass stars (K and M dwarfs) are relatively few. The chemistry of these atmospheres is controlled by the shape and absolute flux of the stellar spectral …
Sn 2012cg: Evidence For Interaction Between A Normal Sn Ia And A Non-Degenerate Binary Companion, G. H. Marion, Peter J. Brown, Jozsef Vinkó, Jeffrey M. Silverman, David J. Sand, Peter Challis, Robert P. Kirshner, J. Craig Wheeler, Perry Berlind, Warren R. Brown, Michael L. Calkins, Yssavo Camacho, Govinda Dhungana, Ryan J. Foley, Andrew S. Friedman, Melissa L. Graham, D. Andrew Howell, Eric Y. Hsiao, Jonathan M. Irwin, Saurabh W. Jha, Robert Kehoe, Lucas M. Macri, Keiichi Maeda, Kaisey Mandel, Curtis Mccully, Viraj Pandya, Kenneth J. Rines, Steven Wilhelmy, Weikang Zheng
Sn 2012cg: Evidence For Interaction Between A Normal Sn Ia And A Non-Degenerate Binary Companion, G. H. Marion, Peter J. Brown, Jozsef Vinkó, Jeffrey M. Silverman, David J. Sand, Peter Challis, Robert P. Kirshner, J. Craig Wheeler, Perry Berlind, Warren R. Brown, Michael L. Calkins, Yssavo Camacho, Govinda Dhungana, Ryan J. Foley, Andrew S. Friedman, Melissa L. Graham, D. Andrew Howell, Eric Y. Hsiao, Jonathan M. Irwin, Saurabh W. Jha, Robert Kehoe, Lucas M. Macri, Keiichi Maeda, Kaisey Mandel, Curtis Mccully, Viraj Pandya, Kenneth J. Rines, Steven Wilhelmy, Weikang Zheng
Physics & Astronomy
We report evidence for excess blue light from the Type Ia supernova (Sn Ia) SN 2012cg at 15 and 16 days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a normal SN Ia. Sixteen days before maximum light, the color of SN 2012cg is 0.2 mag bluer than for other normal SN Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected mag and . Our data set is extensive, …
Hecs-Sz: The Hectospec Survey Of Sunyaev-Zeldovich-Selected Clusters, Kenneth J. Rines, Margaret J. Geller, Antonaldo Diaferio, Ho Seong Hwang
Hecs-Sz: The Hectospec Survey Of Sunyaev-Zeldovich-Selected Clusters, Kenneth J. Rines, Margaret J. Geller, Antonaldo Diaferio, Ho Seong Hwang
Physics & Astronomy
We estimate cluster masses and velocity dispersions for 123 clusters from optical spectroscopy to compare the Sunyaev–Zeldovich (SZ) mass proxy and dynamical masses. Our new survey, HeCS-SZ (Hectospec Cluster Survey of SZ-selected clusters), includes 7721 new or remeasured redshifts from MMT/Hectospec observations of 21 SZ-selected clusters at redshifts z = 0.05–0.20. We supplement the Hectospec data with spectra from the Sloan Digital Sky Survey (SDSS) and cluster data from the Cluster Infall Regions in SDSS project and the Hectospec Cluster Survey, our Hectospec survey of clusters selected by X-ray flux. We measure the scaling relation between velocity dispersion and SZ …
Hectomap And Horizon Run 4: Dense Structures And Voids In The Real And Simulated Universe, Ho Seong Hwang, Margaret J. Geller, Changbom Park, Daniel G. Fabricant, Michael J. Kurtz, Kenneth J. Rines, Juhan Kim, Antonaldo Diaferio, J. Jabran Zahid, Perry Berland, Michael Calkins, Susan Tokarz, Sean Moran
Hectomap And Horizon Run 4: Dense Structures And Voids In The Real And Simulated Universe, Ho Seong Hwang, Margaret J. Geller, Changbom Park, Daniel G. Fabricant, Michael J. Kurtz, Kenneth J. Rines, Juhan Kim, Antonaldo Diaferio, J. Jabran Zahid, Perry Berland, Michael Calkins, Susan Tokarz, Sean Moran
Physics & Astronomy
HectoMAP is a dense redshift survey of red galaxies covering a 53 deg2 strip of the northern sky. HectoMAP is 97% complete for galaxies with r < 20.5, (g− r) > 1.0, and (r − i) > 0.5. The survey enables tests of the physical properties of large-scale structure at intermediate redshift against cosmological models. We use the Horizon Run 4, one of the densest and largest cosmological simulations based on the standard Λ Cold Dark Matter (ΛCDM) model, to compare the physical properties of observed large-scale structures with simulated ones in a volume-limited sample covering 8 × 106 …
Hydrostatic And Caustic Mass Profiles Of Galaxy Clusters, Ben J. Maughan, Paul A. Giles, Kenneth J. Rines, Antonaldo Diaferio, Margaret J. Geller, Nina Van Der Pyl, Massimiliano Bonamente
Hydrostatic And Caustic Mass Profiles Of Galaxy Clusters, Ben J. Maughan, Paul A. Giles, Kenneth J. Rines, Antonaldo Diaferio, Margaret J. Geller, Nina Van Der Pyl, Massimiliano Bonamente
Physics & Astronomy
We compare X-ray and caustic mass profiles for a sample of 16 massive galaxy clusters. We assume hydrostatic equilibrium in interpreting the X-ray data, and use large samples of cluster members with redshifts as a basis for applying the caustic technique. The hydrostatic and caustic masses agree to better than ≈20 per cent on average across the radial range covered by both techniques (∼[0.2–1.25]R500). The mass profiles were measured independently and do not assume a common functional form. Previous studies suggest that, at R500 , the hydrostatic and caustic masses are biased low and high, respectively. …
Disorder Influences The Quantum Critical Transport At A Superconductor-To-Insulator Transition, H Q. Nguyen, Shawna M. Hollen, J M. Valles Jr., J Shainline, J. M. Xu
Disorder Influences The Quantum Critical Transport At A Superconductor-To-Insulator Transition, H Q. Nguyen, Shawna M. Hollen, J M. Valles Jr., J Shainline, J. M. Xu
Physics & Astronomy
We isolated flux disorder effects on the transport at the critical point of the quantum magnetic field tuned superconductor-to-insulator transition (BSIT). The experiments employed films patterned into geometrically disordered hexagonal arrays. Spatial variations in the flux per unit cell, which grow in a perpendicular magnetic field, constitute flux disorder. The growth of flux disorder with magnetic field limited the number of BSITs exhibited by a single film due to flux matching effects. The critical metallic resistance at successive BSITs grew with flux disorder contrary to predictions of its universality. These results open the door for controlled studies of disorder effects …
Characterizing The Rigidly Rotating Magnetosphere Stars Hd 345439 And Hd 23478, J. P. Wisniewski, S. D. Chojnowski, James R. A. Davenport, J. Bartz, J. Pepper, D. G. Whelan, S. S. Eikenberry, J. R. Lomax, S. R. Majewski, N. D. Richardson
Characterizing The Rigidly Rotating Magnetosphere Stars Hd 345439 And Hd 23478, J. P. Wisniewski, S. D. Chojnowski, James R. A. Davenport, J. Bartz, J. Pepper, D. G. Whelan, S. S. Eikenberry, J. R. Lomax, S. R. Majewski, N. D. Richardson
Physics & Astronomy
The SDSS III APOGEE survey recently identified two new σ Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the Kilodegree Extremely Little Telescope, Wide Angle Search for Planets, and ASAS surveys reveals the presence of a ~0.7701 day period in each data set, suggesting the system is among the faster known σ Ori E analogs. We also see clear evidence that the strength of Hα, H …
The Eleventh And Twelfth Data Releases Of The Sloan Digital Sky Survey: Final Data From Sdss-Iii, Shadab Alam, Franco D. Albareti, Carlos Allende Prieto, F. Anders, James R. A. Davenport, Scott F. Anderson, Timothy Anderton, Brett H. Andrews, Eric Armengaud, Éric Aubourg, Stephen Bailey
The Eleventh And Twelfth Data Releases Of The Sloan Digital Sky Survey: Final Data From Sdss-Iii, Shadab Alam, Franco D. Albareti, Carlos Allende Prieto, F. Anders, James R. A. Davenport, Scott F. Anderson, Timothy Anderton, Brett H. Andrews, Eric Armengaud, Éric Aubourg, Stephen Bailey
Physics & Astronomy
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 …
Extreme Geomagnetic Disturbances Due To Shocks Within Cmes, Noe E. Lugaz, Charles J. Farrugia, Chia-Lin L. Huang, Harlan E. Spence
Extreme Geomagnetic Disturbances Due To Shocks Within Cmes, Noe E. Lugaz, Charles J. Farrugia, Chia-Lin L. Huang, Harlan E. Spence
Physics & Astronomy
We report on features of solar wind-magnetosphere coupling elicited by shocks propagating through coronal mass ejections (CMEs) by analyzing the intense geomagnetic storm of 6 August 1998. During this event, the dynamic pressure enhancement at the shock combined with a simultaneous increase in the southward component of the magnetic field resulted in a large earthward retreat of Earth's magnetopause, which remained close to geosynchronous orbit for more than 4 h. This occurred despite the fact that both shock and CME were weak and relatively slow. Another similar example of a weak shock inside a slow CME resulting in an intense …
The Time Domain Spectroscopic Survey: Variable Object Selection And Anticipated Results, Eric Morganson, Paul J. Green, Scott F. Anderson, John J. Ruan, James R. A. Davenport, Adam D. Myers, Michael Eracleous, Brandon Kelly, Carlos Badenes, Eduardo Bañados, Michael R. Blanton
The Time Domain Spectroscopic Survey: Variable Object Selection And Anticipated Results, Eric Morganson, Paul J. Green, Scott F. Anderson, John J. Ruan, James R. A. Davenport, Adam D. Myers, Michael Eracleous, Brandon Kelly, Carlos Badenes, Eduardo Bañados, Michael R. Blanton
Physics & Astronomy
We present the selection algorithm and anticipated results for the Time Domain Spectroscopic Survey (TDSS). TDSS is an Sloan Digital Sky Survey (SDSS)-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) subproject that will provide initial identification spectra of approximately 220,000 luminosity-variable objects (variable stars and active galactic nuclei across 7500 deg2 selected from a combination of SDSS and multi-epoch Pan-STARRS1 photometry. TDSS will be the largest spectroscopic survey to explicitly target variable objects, avoiding pre-selection on the basis of colors or detailed modeling of specific variability characteristics. Kernel Density Estimate analysis of our target population performed on SDSS Stripe 82 …
Detecting Differential Rotation And Starspot Evolution On The M Dwarf Gj 1243 With Kepler, James R. A. Davenport, Leslie Hebb, Suzanne L. Hawley
Detecting Differential Rotation And Starspot Evolution On The M Dwarf Gj 1243 With Kepler, James R. A. Davenport, Leslie Hebb, Suzanne L. Hawley
Physics & Astronomy
We present an analysis of the starspots on the active M4 dwarf GJ 1243, using 4 years of time series photometry from Kepler. A rapid P = 0.592596 ± 0.00021 days rotation period is measured due to the ~2.2% starspot-induced flux modulations in the light curve. We first use a light curve modeling approach, using a Monte Carlo Markov Chain sampler to solve for the longitudes and radii of the two spots within 5 day windows of data. Within each window of time the starspots are assumed to be unchanging. Only a weak constraint on the starspot latitudes can …
Update On Radiation Dose From Galactic And Solar Protons At The Moon Using The Lro/Crater Microdosimeter, J. E. Mazur, Cary Zeitlin, Nathan A. Schwadron, M. D. Looper, Lawrence W. Townsend, J. B. Blake, Harlan E. Spence
Update On Radiation Dose From Galactic And Solar Protons At The Moon Using The Lro/Crater Microdosimeter, J. E. Mazur, Cary Zeitlin, Nathan A. Schwadron, M. D. Looper, Lawrence W. Townsend, J. B. Blake, Harlan E. Spence
Physics & Astronomy
The NASA Lunar Reconnaissance Orbiter (LRO) has been exploring the lunar surface and radiation environment since June 2009. In Mazur et al. [2011] we discussed the first 6 months of mission data from a microdosimeter that is housed within the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument onboard LRO. The CRaTER microdosimeter is an early version of what is now a commercially available hybrid that accurately measures total ionizing radiation dose in a silicon target (http://www.teledynemicro.com/product/radiation-dosimeter). This brief report updates the transition from a deep solar minimum radiation environment to the current …
Butterfly Pitch-Angle Distribution Of Relativistic Electrons In The Outer Radiation Belt: Evidence Of Nonadiabatic Scattering, Nikolai O. Artemyev, O. V. Agapitov, F. S. Mozer, Harlan E. Spence
Butterfly Pitch-Angle Distribution Of Relativistic Electrons In The Outer Radiation Belt: Evidence Of Nonadiabatic Scattering, Nikolai O. Artemyev, O. V. Agapitov, F. S. Mozer, Harlan E. Spence
Physics & Astronomy
In this paper we investigate the scattering of relativistic electrons in the nightside outer radiation belt (around the geostationary orbit). We consider the particular case of low geomagnetic activity (|Dst|<20 nT), quiet conditions in the solar wind, and absence of whistler wave emissions. For such conditions we find several events of Van Allen probe observations of butterfly pitch angle distributions of relativistic electrons (energies about 1–3 MeV). Many previous publications have described such pitch angle distributions over a wide energy range as due to the combined effect of outward radial diffusion and magnetopause shadowing. In this paper we discuss another mechanism that produces butterfly distributions over a limited range of electron energies. We suggest that such distributions can be shaped due to relativistic electron scattering in the equatorial plane of magnetic field lines that are locally deformed by currents of hot ions injected into the inner magnetosphere. Analytical estimates, test particle simulations, and observations of the AE index support this scenario. We conclude that even in the rather quiet magnetosphere, small scale (magnetic local time (MLT)-localized) injection of hot ions from the magnetotail can likely influence the relativistic electron scattering. Thus, observations of butterfly pitch angle distributions can serve as an indicator of magnetic field deformations in the nightside inner magnetosphere. We briefly discuss possible theoretical approaches and problems for modeling such nonadiabatic electron scattering.
Modification Of Electronic Surface States By Graphene Islands On Cu(111), Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta
Modification Of Electronic Surface States By Graphene Islands On Cu(111), Shawna M. Hollen, G A. Gambrel, S J. Tjung, N M. Santagata, Ezekiel Johnston-Halperin, Jay A. Gupta
Physics & Astronomy
We present a study of graphene/substrate interactions on ultrahigh-vacuum-grown graphene islands with minimal surface contamination using in situ low-temperature scanning tunneling microscopy. We compare the physical and electronic structure of the sample surface with atomic spatial resolution on graphene islands versus regions of bare Cu(111) substrate. We find that the Rydberg-like series of image potential states is shifted toward lower energy over the graphene islands relative to Cu(111), indicating a decrease in the local work function, and the resonances have a much smaller linewidth, indicating reduced coupling to the bulk. In addition, we show the dispersion of the occupied Cu(111) …
Disappearance Of Plasmaspheric Hiss Following Interplanetary Shock, Zhenpeng Su, Hui Zhu, Fuliang Xiao, Yuming Wang, Chao Shen, Min Zhang, Shui Wang, C A. Kletzing, W. S. Kurth, G. B. Hospodarsky, Harlan E. Spence, Geoffrey Reeves, H. O. Funsten, J. B. Blake, D. N. Baker, J. R. Wygant
Disappearance Of Plasmaspheric Hiss Following Interplanetary Shock, Zhenpeng Su, Hui Zhu, Fuliang Xiao, Yuming Wang, Chao Shen, Min Zhang, Shui Wang, C A. Kletzing, W. S. Kurth, G. B. Hospodarsky, Harlan E. Spence, Geoffrey Reeves, H. O. Funsten, J. B. Blake, D. N. Baker, J. R. Wygant
Physics & Astronomy
Abstract Plasmaspheric hiss is one of the important plasma waves controlling radiation belt dynamics. Its spatiotemporal distribution and generation mechanism are presently the object of active research. We here give the first report on the shock-induced disappearance of plasmaspheric hiss observed by the Van Allen Probes on 8 October 2013. This special event exhibits the dramatic variability of plasmaspheric hiss and provides a good opportunity to test its generation mechanisms. The origination of plasmaspheric hiss from plasmatrough chorus is suggested to be an appropriate prerequisite to explain this event. The shock increased the suprathermal electron fluxes, and then the enhanced …
Unraveling The Drivers Of The Storm Time Radiation Belt Response, E. K.J. Kilpua, H. Hietala, D. L. Turner, H. E.J. Koskinen, T. I. Pulkkinen, J. V. Rodriguez, Geoffrey Reeves, S. Claudepierre, Harlan E. Spence
Unraveling The Drivers Of The Storm Time Radiation Belt Response, E. K.J. Kilpua, H. Hietala, D. L. Turner, H. E.J. Koskinen, T. I. Pulkkinen, J. V. Rodriguez, Geoffrey Reeves, S. Claudepierre, Harlan E. Spence
Physics & Astronomy
We present a new framework to study the time evolution and dynamics of the outer Van Allen belt electron fluxes. The framework is entirely based on the large-scale solar wind storm drivers and their substructures. The Van Allen Probe observations, revealing the electron flux behavior throughout the outer belt, are combined with continuous, long-term (over 1.5 solar cycles) geosynchronous orbit data set from GOES and solar wind measurements A superposed epoch analysis, where we normalize the timescales for each substructure (sheath, ejecta, and interface region) allows us to avoid smearing effects and to distinguish the electron flux evolution during various …
Energetic, Relativistic And Ultra-Relativistic Electrons: Comparison Of Long-Term Verb Code Simulations With Van Allen Probes Measurements, A. Drozdov, Y. Y. Shprits, K. Orlova, A. C. Kellerman, D. A. Subbotin, D. N. Baker, Harlan E. Spence, Geoffrey Reeves
Energetic, Relativistic And Ultra-Relativistic Electrons: Comparison Of Long-Term Verb Code Simulations With Van Allen Probes Measurements, A. Drozdov, Y. Y. Shprits, K. Orlova, A. C. Kellerman, D. A. Subbotin, D. N. Baker, Harlan E. Spence, Geoffrey Reeves
Physics & Astronomy
In this study, we compare long-term simulations performed by the Versatile Electron Radiation Belt (VERB) code with observations from the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope instruments on the Van Allen Probes satellites. The model takes into account radial, energy, pitch angle and mixed diffusion, losses into the atmosphere, and magnetopause shadowing. We consider the energetic (>100 keV), relativistic (~0.5–1 MeV), and ultrarelativistic (>2 MeV) electrons. One year of relativistic electron measurements (μ = 700 MeV/G) from 1 October 2012 to 1 October 2013 are well reproduced by the simulation during varying levels of geomagnetic …
Analysis Of Plasmaspheric Hiss Wave Amplitudes Inferred From Low-Altitude Poes Electron Data: Technique Sensitivity Analysis, M. De Soria-Santacruz, W. Li, R. M. Thorne, Q. Ma, J. Bortnik, B. Ni, C A. Kletzing, W. S. Kurth, G. B. Hospodarsky, Harlan E. Spence, Geoffrey Reeves, J. B. Blake, Joseph F. Fennell
Analysis Of Plasmaspheric Hiss Wave Amplitudes Inferred From Low-Altitude Poes Electron Data: Technique Sensitivity Analysis, M. De Soria-Santacruz, W. Li, R. M. Thorne, Q. Ma, J. Bortnik, B. Ni, C A. Kletzing, W. S. Kurth, G. B. Hospodarsky, Harlan E. Spence, Geoffrey Reeves, J. B. Blake, Joseph F. Fennell
Physics & Astronomy
A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the Polar Operational Environmental Satellites (POES) spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conjunction events with the Van Allen Probes. These amplitudes are calculated with different input models …