Astrophysics and Astronomy Commons^™

Strategies For Detecting Biological Molecules On Titan, Catherine Neish, Ralph Lorenz, Elizabeth Turtle, Jason Barnes, Melissa Trainer, Bryan Stiles, Randolph Kirk, Charles Hibbitts, Michael Malaska

Earth Sciences Publications

Saturn’s moon Titan has all the ingredients needed to produce “life as we know it”. When exposed to liquid water, organic molecules analogous to those found on Titan produce a range of biomolecules such as amino acids. Titan thus provides a natural laboratory for studying the products of prebiotic chemistry. In this work, we examine the ideal locales to search for evidence of, or progression towards, life on Titan. We determine that the best sites to identify biological molecules are deposits of impact melt on the floors of large, fresh impact craters, specifically Sinlap, Selk, and Menrva craters. We find …

Narrowing Of Plasmon Resonance Peaks As An Ensemble Effect, Zhutian Ding, James M. Stubbs, Silvia Mittler

Physics and Astronomy Publications

The frequency of localized surface plasmon resonance (LSPR) displayed by gold nanoparticles (AuNPs) redshifts as a function of their local refractive index, which renders them valuable transducers for sensing applications. An ensemble hypothesis is presented herein, along with spectroscopic evidence, using the biotin-streptavidin system on immobilized AuNPs to interpret the decrease in ensemble linewidth (ELW) consistently observed upon functionalization of plasmonic nanoparticles and the subsequent analyte binding. These results demonstrate that ELW can be used to monitor recognition reactions, providing spectral details and a possible sensitivity enhancement to the conventional wavelength sensing. A novel sensing platform allowing the simultaneous measurement …

A Mass-Producible And Versatile Sensing System: Localized Surface Plasmon Resonance Excited By Individual Waveguide Modes, Zhutian Ding, James M. Stubbs, Danielle Mcrae, Johanna M. Blacquiere, François Lagugné-Labarthet, Silvia Mittler

Physics and Astronomy Publications

A plasmonic sensing system that allows the excitation of localized surface plasmon resonance (LSPR) by individual waveguide modes is presented conceptually and experimentally. Any change in the local environment of the gold nanoparticles (AuNPs) alters the degree of coupling between LSPR and a polymer slab waveguide, which then modulates the transmission-output signal. In comparison to conventional LSPR sensors, this system is less susceptible to optical noise and positional variation of signals. Moreover, it enables more freedom in the exploitation of plasmonic hot spots with both transverse electric (TE) and transverse magnetic (TM) modes. Through real-time measurement, it is demonstrated that …

Polymer Margination In Uniform Shear Flows, Venkat Balasubramanian, Colin Denniston

Physics and Astronomy Publications

We address the issue of polymer margination (migration towards surfaces) in uniform shear flows through extensive LBMD (lattice-Boltzmann molecular dynamics) simulations. In particular we consider the effect of monomer size, a on the chain's overall margination tendency for chains of length N = 16, 32 monomers in flows at multiple shear rates . We observed higher margination of chains with larger radii monomers in comparison to smaller radii monomer chains of the same length N. We quantify this effect by considering various measures such as the distribution of the maximum extent of the chain into the channel bulk, z …

Electrical Detection Of Charge-To- Spin And Spin-To-Charge Conversion In A Topological Insulator Bi2te3 Using Bn/Al2o3 Hybrid Tunnel Barrier, C.H. Li, O.M.J. Van't Erve, C. Yan, L. Li, B.T. Jonker

Faculty & Staff Scholarship

One of the most striking properties of three-dimensional topological insulators (TIs) is spin-momentum locking, where the spin is locked at right angles to momentum and hence an unpolarized charge current creates a net spin polarization. Alternatively, if a net spin is injected into the TI surface state system, it is distinctively associated with a unique carrier momentum and hence should generate a charge accumulation, as in the so-called inverse Edelstein effect. Here using a Fe/Al2O3/BN tunnel barrier, we demonstrate both effects in a single device in Bi2Te3: the electrical detection of the spin accumulationgenerated by an unpolarized current flowing through …

Gamma-Ray-Emitting Narrow-Line Seyfert 1 Galaxies In The Sloan Digital Sky Survey, Vaidehi S. Paliya, M. Ajello, A. Mandal, C. S. Stalin, A. Kaur, D. Hartmann

Publications

The detection of significant γ-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1s) galaxies enables us to study jets in environments different than those in blazars. However, due to the small number of known γ-ray-emitting NLSy1 (γ-NLSy1) galaxies, a comprehensive study could not be performed. Here, we report the first detection of significant γ-ray emission from four active galactic nuclei (AGNs), recently classified as NLSy1 from their Sloan Digital Sky Survey (SDSS) optical spectrum. Three flat-spectrum radio quasars (FSRQs) present in the third Large Area Telescope AGN catalog (3LAC) are also found as γ-NLSy1 galaxies. …

Spectral–Timing Analysis Of Kilohertz Quasi–Periodic Oscillations In Neutron Star Low Mass X-Ray Binaries, Jon Troyer

Wayne State University Dissertations

Kilohertz quasi-periodic oscillations or kHz QPOs are X-ray intensity variations observed

in neutron star low-mass X-ray binary (LMXB) systems. In such systems, matter is transferred

from a secondary low-mass star to a neutron star via the process of accretion. kHz

QPOs occur on the timescale of the inner accretion flow and may carry signatures of the

physics of strong gravity (c2 ~GM/R) and possibly clues to constraining the neutron star

equation of state (EOS). No model to date has been able to illuminate the origin of kHz

QPOs. Spectral-timing is a set of analysis techniques useful in deriving information about …

Electrostatic Potential And Valence Modulation In La0.7sr0.3mno3 Thin Films, Robbyn Trappen, A. C. Garcia- Castro, Vu Thanh Tra, Chih-Yeh Huang, Wilfredo Ibarra-Hernandez, James Fitch, Sobhit Singh, Jingling Zhou, Guerau Cabrera, Ying-Hao Chu, James M. Lebeau, Aldo H. Romero, Mikel B. Holcomb

Faculty & Staff Scholarship

The Mn valence in thin film La0.7Sr0.3MnO3 was studied as a function of film thickness in the range of 1–16 unit cells with a combination of non-destructive bulk and surface sensitive X-ray absorption spectroscopy techniques. Using a layer-by-layer valence model, it was found that while the bulk averaged valence hovers around its expected value of 3.3, a significant deviation occurs within several unit cells of the surface and interface. These results were supported by first principles calculations. The surface valence increases to up to Mn3.7+, whereas the interface valence reduces down to Mn2.5+. The change in valence from the expected …

Multidimensional Item Response Theory And The Force Concept Inventory, John Stewart, Cabot Zabriskie, Seth Devore, Gay Stewart

Faculty & Staff Scholarship

Research on the test structure of the Force Concept Inventory (FCI) has largely been performed with exploratory methods such as factor analysis and cluster analysis. Multidimensional Item Response Theory (MIRT) provides an alternative to traditional exploratory factor analysis which allows statistical testing to identify the optimal number of factors. Application of MIRT to a sample of N 1⁄4 4716 FCI post-tests identified a 9-factor solution as optimal. Additional analysis showed that a substantial part of the identified factor structure resulted from the practice of using problem blocks and from pairs of similar questions. Applying MIRT to a reduced set of …

Robust Topological Phase In Proximitized Core–Shell Nanowires Coupled To Multiple Superconductors, Tudor D. Stanescu, Anna Stitek, Andrei Manolescu

Faculty & Staff Scholarship

We consider core–shell nanowires with prismatic geometry contacted with two or more superconductors in the presence of a mag- netic field applied parallel to the wire. In this geometry, the lowest energy states are localized on the outer edges of the shell, which strongly inhibits the orbital effects of the longitudinal magnetic field that are detrimental to Majorana physics. Using a tight-binding model of coupled parallel chains, we calculate the topological phase diagram of the hybrid system in the presence of non-vanishing transverse potentials and finite relative phases between the parent superconductors. We show that having finite relative phases strongly …

Kelt-19ab: A P ∼ 4.6-Day Hot Jupiter Transiting A Likely Am Star With A Distant Stellar Companion, R. J. Siverd, K. A. Collins, G. Zhou, S. N. Quinn, B. S. Gaudi, K. G. Stassun, M. C. Johnson, A. Bieryla, D. W. Latham, D. R. Ciardi, J. E. Rodriguez, K. Penev, M. Pinsonneault, J. Pepper, J. D. Eastman, H. Relles, J. F. Kielkopf, J. Gregorio, T. E. Oberst, G. F. Aldi, G. A. Esquerdo, M. L. Calkins, P. Berlind, C. D. Dressing, R. Patel, D. J. Stevens, T. G. Beatty, M. B. Lund, J. Labadie-Bartz, R. B. Kuhn, K. D. Colón, D. James, X. Yao, J. A. Johnson, J. T. Wright, N. Mccrady, R. A. Wittenmyer, S. A. Johnson, D. H. Sliski, Eric L.N. Jensen, David H. Cohen, K. K. Mcleod, M. T. Penny, M. D. Joner, D. C. Stephens, S. Villanueva Jr., R. Zambelli, C. Stockdale, P. Evans, T.-G. Tan, I. A. Curtis, P. A. Reed, M. Trueblood, P. Trueblood

Physics & Astronomy Faculty Works

We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright (V ~ 9.9) A8V star TYC 764-1494-1 with an orbital period of 4.61 days. We confirm the planetary nature of the companion via a combination of radial velocities, which limit the mass to ≲ 4.1 M_J (3σ), and a clear Doppler tomography signal, which indicates a retrograde projected spin–orbit misalignment of λ = -179.7 (+3.7)/(-3.8) degrees. Global modeling indicates that the T_eff = 7500 ± 110 K host star has M_* = 1.62 (+0.25)/(-0.20) M_⊙ and R_* = …

The [Cii] 158ΜM Line Emission In High-Redshift Galaxies, Guilaine Lagache, Morgane Cousin, Marios Chatzikos

Physics and Astronomy Faculty Publications

Gas is a crucial component of galaxies, providing the fuel to form stars, and it is impossible to understand the evolution of galaxies without knowing their gas properties. The [CII] fine structure transition at 158 μm is the dominant cooling line of cool interstellar gas, and is the brightest of emission lines from star forming galaxies from FIR through metre wavelengths, almost unaffected by attenuation. With the advent of ALMA and NOEMA, capable of detecting [CII]-line emission in high-redshift galaxies, there has been a growing interest in using the [CII] line as a probe of the physical conditions of …

Spatially Resolved Dust, Gas, And Star Formation In The Dwarf Magellanic Irregular Ngc 4449, D. Calzetti, G W. Wilson, B. T. Draine, H. Roussel, K. E. Johnson, M. H. Heyer, W. F. Wall, K. Grasha, A. Battisti, J. E. Andrews, A. Kirkpatrick, D. Rosa González, O. Vega, J. Puschnig, M. Yun, G. Östlin, A. S. Evans, Y. Tang, James Lowenthal, D. Sánchez-Arguelles

Astronomy: Faculty Publications

We investigate the relation between gas and star formation in subgalactic regions, ˜360 pc to ˜1.5 kpc in size, within the nearby starburst dwarf NGC 4449, in order to separate the underlying relation from the effects of sampling at varying spatial scales. Dust and gas mass surface densities are derived by combining new observations at 1.1 mm, obtained with the AzTEC instrument on the Large Millimeter Telescope, with archival infrared images in the range 8-500 μm from the Spitzer Space Telescope and the Herschel Space Observatory. We extend the dynamic range of our millimeter (and dust) maps at the faint …

Automated Data Processing Architecture For The Gemini Planet Imager Exoplanet Survey, Jason J. Wang, Marshall D. Perrin, Dmitry Savransky, Pauline Arriaga, Jeffrey K. Chilcote, Robert J. De Rosa, Maxwell A. Millar-Blanchaer, Christian Marois, Julien Rameau, Schuyler G. Wolff, Jacob Shapiro, Jean Baptiste Ruffio, Jérôme Maire, Franck Marchis, James R. Graham, Bruce Macintosh, S. Mark Ammons, Vanessa P. Bailey, Travis S. Barman, Sebastian Bruzzone, Joanna Bulger, Tara Cotton, René Doyon, Gaspard Duchêne, Michael P. Fitzgerald, Katherine B. Follette, Stephen Goodsell, Alexandra Z. Greenbaum, Pascale Hibon, Li Wei Hung, Patrick Ingraham, Paul Kalas, Kimberly Ward-Duong, Et Al

Astronomy: Faculty Publications

The Gemini Planet Imager Exoplanet Survey (GPIES) is a multiyear direct imaging survey of 600 stars to discover and characterize young Jovian exoplanets and their environments. We have developed an automated data architecture to process and index all data related to the survey uniformly. An automated and flexible data processing framework, which we term the Data Cruncher, combines multiple data reduction pipelines (DRPs) together to process all spectroscopic, polarimetric, and calibration data taken with GPIES. With no human intervention, fully reduced and calibrated data products are available less than an hour after the data are taken to expedite follow up …

Climate Modeling, Outgoing Longwave Radiation, And Tropical Cyclone Forecasting, Thomas Rechtman

Honors Undergraduate Theses

Climate modeling and tropical cyclone forecasting are two significant is- sues that are continuously being improved upon for more accurate weather forecasting and preparedness. In this thesis, we have studied three climate models and formulated a new model with a view to determine the outgoing longwave radiation (OLR) budget at the top of the atmosphere (TOA) as ob- served by the National Oceanic and Atmospheric Administration’s (NOAA) satellite based Advanced Very High Resolution Radiometer (AVHRR). In 2006, Karnauskas proposed the African meridional OLR as an Atlantic hur- ricane predictor, the relation was further proven in 2016 by Karnauskas and Li …

Future Nuisance Flooding In Norfolk, Va, From Astronomical Tides And Annual To Decadal Internal Climate Variability, A. G. Burgos, B. D. Hamlington, P. R. Thompson, R. D. Ray

OES Faculty Publications

Increasing sea level rise will lead to more instances of nuisance flooding along the Virginia coastline in the coming decades, causing road closures and deteriorating infrastructure. These minor flood events can be caused by astronomical tides alone, in addition to internal climate variability on annual to decadal timescales. An assessment of nuisance flooding from these two effects is presented up until the year 2050 for Norfolk, Virginia. The analysis of water levels indicates that nuisance flooding from tides alone in conjunction with a medium-high sea level scenario will result in flooding beginning in 2030 with frequency increasing thereafter. The addition …

Relationship Between Interplanetary Conditions And Changes In The Geomagnetic Field To Understand The Causes Of Geomagnetically Induced Currents, Cameron P. Maillet

Honors Theses and Capstones

Geomagnetically Induced Currents (GICs) are electrical currents induced in ground-level conductive networks, like power lines and pipelines, which can cause costly damage to infrastructure. GICs are induced in response to fast changes in the geomagnetic field (GMF) according to Faraday’s Law of Electromagnetic Induction. The purpose of this study was to identify the parameters of the solar wind and interplanetary shocks which are most strongly correlated with large, fast changes in the magnitude of the GMF. GMF data is 1-min averaged time series of mid- and high-latitude magnetometer measurements in the Sym/H and AL indices, respectively. For solar wind data, …

Observations Of Ion Density And Temperature Around The International Space Station During Two Geomagnetic Storms, Alex M. Wright

Honors Theses and Capstones

The International Space Station (ISS) is a low Earth orbit research facility and host to an international crew. Geomagnetic storms cause changes in the Earth’s magnetic field and affect the ion density and temperature in the ionosphere which could pose a hazard to ISS crew. This hazard is measured by the Floating Potential Measurement Unit (FPMU) which measures ion density, ion temperature, and the charge differential of the ISS relative to its surrounding environment. I analyzed data collected by Narrow Sweep Langmuir Probe for two storms in 2015. Ion density and temperature were affected by geomagnetic storms, but the effects …

Foreword By Guest Editors Maa 2018 Volume 18 Issue 4, Frank Prendergast, A. César González-García, Gary Wells, Juan Antonio Belmonte

Conference Papers

MAA SPECIAL ISSUE VOL 18 ISSUE 4:

Sixty-three (63) Selected (peer reviewed) Papers of the INSAP X – Oxford XI – SEAC 25th Joint Conference ‘ROAD TO THE STARS’, held in Santiago de Compostela, Spain, 18th–22nd September 2017

Mediterranean Archaeology and Archaeometry (MAA) is an Open Access Journal published since 2001 by The University of the Aegean, Department of Mediterranean Studies, Rhodes, Greece.

It covers the dual nature of archaeology and cultural heritage with science which includes, amongst others, natural science applied to archaeology (physics, chemistry, biology, geology, geophysics, astronomy), archaeology, ancient history, cultural sustainability, astronomy in culture, physical anthropology, …

Pathways To The Cosmos:The Alignment Of Megalithic Tombs In Ireland And Atlantic Europe, Frank Prendergast, Gabriel Cooney

Articles

Gabriel Cooney and Frank Prendergast present the context of and outline the approach to this one-day conference organised by Archaeology Ireland on behalf of the National Monuments Service at the Department of Culture, Heritage and the Gaeltacht and the Office of Public Works to mark the European Year of Cultural Heritage 2018. The event will take place at Dublin Castle on 15 September 2018.

Solar Alignment And The Irish Passage Tomb Tradition, Frank Prendergast

Book/Book Chapter

A succinct and very useful, illustrated, explanatory guide to the phenomenon of solar alignment in the irish Passage Tomb tradition. Includes a listing of where to visit the 15 known astronomically aligned passage tombs in the 32 counties.

Written by Dr Frank Prendergast who is now Emeritus at the Dublin Institute of Technology, where he researches Irish prehistoric monuments and their landscapes from a cultural astronomy perspective. His current interests and publications are on the meaning of the dark sky in the prehistoric past and on the conservation of archaeological landscapes from light pollution.

Heritage Guides are included free with …

Groundwater Withdrawals Under Drought: Reconciling Grace And Land Surface Models In The United States High Plains Aquifer, Wanshu Nie, Benjamin Zaitchik, Matthew Rodell, Sujay V. Kumar, Martha C. Anderson, Christopher Hain

United States National Aeronautics and Space Administration: Publications

Advanced Land Surface Models (LSM) offer a powerful tool for studying hydrological variability. Highly managed systems, however, present a challenge for these models, which typically have simplified or incomplete representations of human water use. Here we examine recent groundwater declines in the US High Plains Aquifer (HPA), a region that is heavily utilized for irrigation and that is also affected by episodic drought. To understand observed decline in groundwater and terrestrial water storage during a recent multiyear drought, we modify the Noah-MP LSM to include a groundwater irrigation scheme. To account for seasonal and interannual variability in active irrigated area, …

Two Decades Old Entropy Stable Method For The Euler Equations Revisited, Björn Sjögreen, H. C. Yee

United States National Aeronautics and Space Administration: Publications

The two decades old high order central differencing via entropy splitting and summation-by-parts (SBP) difference closure of Olsson and Oliger, Gerritsen and Olsson, and Yee et al. [2, 7, 25] is revisited. The entropy splitting is a form of skewsymmetric splitting in terms of the physical entropy of the nonlinear Euler flux derivatives. Central differencing applied to the entropy splitting form of the Euler flux derivatives together with SBP difference operators will, hereafter, be referred to as entropy split schemes.

The Leech Exoplanet Imaging Survey: Limits On Planet Occurrence Rates Under Conservative Assumptions, Jordan M. Stone, Andrew J. Skemer, Philip M. Hinz, Mariangela Bonavita, Kaitlin M. Kratter, Anne Lise Maire, Denis Defrere, Vanessa P. Bailey, Eckhart Spalding, Jarron M. Leisenring, S. Desidera, M. Bonnefoy, Beth Biller, Charles E. Woodward, Th Henning, Michael F. Skrutskie, J. A. Eisner, Justin R. Crepp, Jennifer Patience, Gerd Weigelt, Robert J. De Rosa, Joshua Schlieder, Wolfgang Brandner, Dániel Apai, Kate Su, Steve Ertel, Kimberly Ward-Duong, Katie M. Morzinski, Dieter Schertl, Karl Heinz Hofmann, Laird M. Close, Stefan S. Brems

Astronomy: Faculty Publications

We present the results of the largest L' (3.8 μm) direct imaging survey for exoplanets to date, the Large Binocular Telescope Interferometer Exozodi Exoplanet Common Hunt (LEECH). We observed 98 stars with spectral types from B to M. Cool planets emit a larger share of their flux in L' compared to shorter wavelengths, affording LEECH an advantage in detecting low-mass, old, and cold-start giant planets. We emphasize proximity over youth in our target selection, probing physical separations smaller than other direct imaging surveys. For FGK stars, LEECH outperforms many previous studies, placing tighter constraints on the hot-start planet occurrence frequency …

Determining The Small-Scale Structure And Particle Properties In Saturn's Rings From Stellar And Radio Occultations, Richard Jerousek

Electronic Theses and Dissertations

Saturn's rings consist of icy particles of various sizes ranging from millimeters to several meters. Particles may aggregate into ephemeral elongated clumps known as self-gravity wakes in regions where the surface mass density and epicyclic frequency give a Toomre critical wavelength which is much larger than the largest individual particles (Julian and Toomre 1966). Optical depth measurements at different wavelengths can be used to constrain the sizes of individual particles (Zebker et al. 1985, Marouf et al. 1983) while measurements of optical depths spanning many viewing geometries can be used to determine the properties of self-gravity wakes (Colwell et al. …

Item-Level Gender Fairness In The Force And Motion Conceptual Evaluation And The Conceptual Survey Of Electricity And Magnetism, Rachel Henderson, Paul Miller, John Stewart, Adrienne Traxler, Rebecca Lindell

Faculty & Staff Scholarship

Gender gaps on the most widely used conceptual inventories created by physics education researchers have been extensively studied. Most of the research exploring the consistent gender gaps has been performed at the student level using the total evaluation score; less research has been performed examining these assessments at the item level and this research has been predominately restricted to the Force Concept Inventory (FCI). Many studies have identified subsets of FCI items as unfair to either men or women. An item is fair if men and women of equal ability in conceptual physics score equally on the item. This study …

Single-Site Catalyst Promoters Accelerate Metal- Catalyzed Nitroarene Hydrogenation, Liang Wang, Erjia Guan, Jian Zhang, Junhao Yang, Yihan Zhu, Yu Han, Ming Yang, Cheng Cen, Gang Fu, Bruce C. Gates, Feng-Shou Xiao

Faculty & Staff Scholarship

Atomically dispersed supported metal catalysts are drawing wide attention because of the opportunities they offer for new catalytic properties combined with efficient use of the metals. We extend this class of materials to catalysts that incorporate atomically dispersed metal atoms as promoters. The catalysts are used for the challenging nitroarene hydro- genation and found to have both high activity and selectivity. The promoters are single-site Sn on TiO2 supports that incorporate metal nanoparticle catalysts. Represented as M/Sn- TiO2 (M = Au, Ru, Pt, Ni), these catalysts decidedly outperform the unpromoted supported metals, even for hydrogenation of nitroarenes substituted with various …

Correlation Between Emission Lines And Radio Luminosities Of Active Galactic Nuclei, Jessica Short-Long

Theses and Dissertations--Physics and Astronomy

Radio-loud active galactic nuclei (AGN) are one class of objects associated with accretion activity onto supermassive black holes in centers of massive galaxies. They are believed to be in a radiatively-inefficient accretion mode with low accretion rate. To understand this accretion mode, it is important to measure its radiative output at high energies (> 13.6eV), which can be traced through optical emission lines. However, little is known about their true radiative output. This is because no correlation between optical emission-line and radio luminosity has been found for the majority of low-luminosity radio AGN, which are often classified as low-excitation radio …

Differentiation In Impact Melt Sheets As A Mechanism To Produce Evolved Magmas On Mars, Ari Koeppel

Dissertations and Theses

Asteroid bombardment contributed to extensive melting and resurfacing of ancient (> 3 Ga) Mars, thereby influencing the early evolution of the Martian crust. However, information about how impact melting has altered Mars’ crustal petrology is limited. Evidence from some of the largest impact structures on Earth, such as Sudbury and Manicouagan, suggests that some impact melt sheets experience chemical differentiation. If these processes occur on Mars, we expect to observe differentiated igneous materials in some exhumed rock samples. Some rocks observed in Gale crater are enriched in alkalis (up to 14 wt% Na₂O + K₂O) and …

Whole Earth Telescope Discovery Of A Strongly Distorted Quadrupole Pulsation In The Largest Amplitude Rapidly Oscillating Ap Star, Daniel L. Holdsworth, Donald W. Kurtz, Hideyuki Saio, Judith L. Provençal, Bruno Letarte, Ramotholo R. Sefako, Véronique Petit, Barry Smalley, H. Thomsen, C. L. Fletcher

Aerospace, Physics, and Space Science Faculty Publications

We present a new analysis of the rapidly oscillating Ap (roAp) star, 2MASS J19400781 - 4420093 (J1940; V = 13.1). The star was discovered using SuperWASP broad-band photometry to have a frequency of 176.39 d-1 (2041.55 μHz; P = 8.2min; Holdsworth et al. 2014a) and is shown here to have a peak-to-peak amplitude of 34 mmag. J1940 has been observed during three seasons at the South African Astronomical Observatory, and has been the target of a Whole Earth Telescope campaign. The observations reveal that J1940 pulsates in a distorted quadrupole mode with unusual pulsational phase variations. A higher signal-to-noise ratio …