Astrophysics and Astronomy Commons^™

Aggregate Effects Of Proliferating Low-Earth-Orbit Objects And Implications For Astronomical Data Lost In The Noise, John C. Barentine, Aparna Venkatesan, Jessica Heim, James Lowenthal, Miroslav Kocifaj, Salvador Bará

Astronomy: Faculty Publications

The rising population of artificial satellites and associated debris in low-altitude orbits is increasing the overall brightness of the night sky, threatening ground-based astronomy as well as a diversity of stakeholders and ecosystems reliant on dark skies. We present calculations of the potentially large rise in global sky brightness from space objects in low Earth orbit, including qualitative and quantitative assessments of how professional astronomy may be affected. Debris proliferation is of special concern: we calculate that all log-decades in debris size contribute approximately the same amount of night sky radiance, so debris-generating events are expected to lead to a …

Correlating Changes In Spot Filling Factors With Stellar Rotation: The Case Of Lkca 4, Facundo Pérez Paolino, Jeffrey S. Bary, Michael S. Petersen, Kimberly Ward-Duong, Benjamin M. Tofflemire, Katherine B. Follette, Heidi Mach

Astronomy: Faculty Publications

We present a multi-epoch spectroscopic study of LkCa 4, a heavily spotted non-accreting T Tauri star. Using SpeX at NASA’s Infrared Telescope Facility (IRTF), 12 spectra were collected over five consecutive nights, spanning ≈1.5 stellar rotations. Using the IRTF SpeX Spectral Library, we constructed empirical composite models of spotted stars by combining a warmer (photosphere) standard star spectrum with a cooler (spot) standard weighted by the spot filling factor, f spot. The best-fit models spanned two photospheric component temperatures, T phot = 4100 K (K7V) and 4400 K (K5V), and one spot component temperature, T spot = 3060 K (M5V) …

Direct Discovery Of The Inner Exoplanet In The Hd 206893 System: Evidence For Deuterium Burning In A Planetary-Mass Companion, S. Hinkley, S. Lacour, G. D. Marleau, A. M. Lagrange, J. J. Wang, J. Kammerer, A. Cumming, M. Nowak, L. Rodet, T. Stolker, W. O. Balmer, S. Ray, M. Bonnefoy, P. Mollière, C. Lazzoni, G. Kennedy, C. Mordasini, R. Abuter, S. Aigrain, A. Amorim, R. Asensio-Torres, C. Babusiaux, M. Benisty, J. P. Berger, H. Beust, S. Blunt, A. Boccaletti, Kimberly Ward-Huong, Et Al

Astronomy: Faculty Publications

Aims. HD 206893 is a nearby debris disk star that hosts a previously identified brown dwarf companion with an orbital separation of ~ 10 au. Long-Term precise radial velocity (RV) monitoring, as well as anomalies in the system proper motion, has suggested the presence of an additional, inner companion in the system. Methods. Using information from ongoing precision RV measurements with the HARPS spectrograph, as well as Gaia host star astrometry, we have undertaken a multi-epoch search for the purported additional planet using the VLTI/GRAVITY instrument. Results. We report a high-significance detection over three epochs of the companion HD 206893c, …

Merging Black Holes: Assessing The Performance Of Two Analytic Gravitational Waves Models, Dillon Buskirk, Maria Babiuc-Hamilton

Physics Faculty Research

Merging black holes produce the loudest signal in the detectors. However, this is the most difficult signal to accurately predict with analytical techniques. Only computer simulations can account for the nonlinear physics during the collision, but they are inherently complex, costly, and affected by numerical errors. In order to bypass this problem, two analytical models for the merger have been developed: the Implicit Rotating Source (IRS) and the newer Backwards one Body (BoB). In this work, we assess the performance of the BoB model by comparing it with the older IRS model and with the numerical data, identifying its strengths …

Clumpy Wind Studies And The Nondetection Of A Cyclotron Line In Oao 1657–415, Pragati Pradhan, Carlo Ferrigno, Biswajit Paul, Enrico Bozzo, Ileyk El Mellah, David P. Huenemoerder, James F. Steiner, Victoria Grinberg, Felix Furst, Chandreyee Maitra, Patrizia Romano, Peter Kretschmar, Jamie Kennea, Deepto Chakrabarty

Publications

Winds of massive stars are suspected to be inhomogeneous (or clumpy), which biases the measures of their mass-loss rates. In high-mass X-ray binaries (HMXBs), the compact object can be used as an orbiting X-ray point source to probe the wind and constrain its clumpiness. We perform a spectrotiming analysis of the HMXB OAO 1657–415 with nonsimultaneous NuSTAR and NICER observations. We compute the hardness ratio from the energy-resolved light curves, and, using an adaptive rebinning technique, we thus select appropriate time segments to search for rapid spectral variations on timescales of a few hundred to thousands of seconds. The column …

Calculating MBh Scaling Relations For Agns Using 2d Galaxy Decomposition Software To Analyse Hst Images, Jewel A. Capili

Physics

This study uses the 2D galaxy decomposition software GALFIT developed by Dr. Chien Peng to analyse Hubble Space Telescope images of 14 Active Galactic Nuclei (AGNs) and obtain their M_BH-spheroid luminosity scaling relations for comparison with previous studies.

Evolution Of Coronal Magnetic Field Parameters During X5.4 Solar Flare, Seth H. Garland, Benjamin F. Akers, Vasyl B. Yurchyshyn, Robert D. Loper, Daniel J. Emmons

Faculty Publications

The coronal magnetic field over NOAA Active Region 11,429 during a X5.4 solar flare on 7 March 2012 is modeled using optimization based Non-Linear Force-Free Field extrapolation. Specifically, 3D magnetic fields were modeled for 11 timesteps using the 12-min cadence Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager photospheric vector magnetic field data, spanning a time period of 1 hour before through 1 hour after the start of the flare. Using the modeled coronal magnetic field data, seven different magnetic field parameters were calculated for 3 separate regions: areas with surface |Bz| ≥ 300 G, areas of flare brightening seen …

Non-Hermitian Floquet-Free Analytically Solvable Time-Dependent Systems, Hamed Ghaemi-Dizicheh, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

The non-Hermitian models, which are symmetric under parity (P) and time-reversal (T) operators, are the cornerstone for the fabrication of new ultra-sensitive optoelectronic devices. However, providing the gain in such systems usually demands precise control of nonlinear processes, limiting their application. In this paper, to bypass this obstacle, we introduce a class of time-dependent non-Hermitian Hamiltonians (not necessarily Floquet) that can describe a two-level system with temporally modulated on-site potential and couplings. We show that implementing an appropriate non-Unitary gauge transformation converts the original system to an effective one with a balanced gain and loss. This …

Patchy Forsterite Clouds In The Atmospheres Of Two Highly Variable Exoplanet Analogs, Johanna M. Vos, Ben Burningham, Jacqueline K. Faherty, Sherelyn Alejandro, Eileen Gonzales, Emily Calamari, Daniella Bardalez Gagliuffi, Channon Visscher, Xianyu Tan, Caroline V. Morley, Mark Marley, Marina E. Gemma, Niall Whiteford, Josefine Gaarn, Grace Park

Faculty Work Comprehensive List

We present an atmospheric retrieval analysis of a pair of highly variable, ∼200 Myr old, early T type planetary-mass exoplanet analogs SIMP J01365662+0933473 and 2MASS J21392676+0220226 using the Brewster retrieval framework. Our analysis, which makes use of archival 1–15 μm spectra, finds almost identical atmospheres for both objects. For both targets, we find that the data is best described by a patchy, high-altitude forsterite (Mg2SiO4) cloud above a deeper, optically thick iron (Fe) cloud. Our model constrains the cloud properties well, including the cloud locations and cloud particle sizes. We find that the patchy forsterite slab cloud inferred from our …

How Noise Thresholds Affect The Information Content Of Stellar Flare Sequences, Elmer C. Rivera, Jay R. Johnson, Jonathan Homan, Simon Wing

Faculty Publications

Systems that exhibit discrete dynamics can be well described and reconstructed by considering the set of time intervals between the discrete events of the system. The Kepler satellite has cataloged light curves for many Sun-like stars, and these light curves show strong bursts in intensity that are associated with stellar flares. The waiting time between these flares describes the fundamental dynamics of the stars and is driven by physical processes, such as flux emergence. While it is rather straightforward to identify large flares, the identification of weaker flares can be challenging because of the presence of noise. A common practice …

3d Mhd Models Of The Centrifugal Magnetosphere From A Massive Star With An Oblique Dipole Field, Asif Ud-Doula, Stanley P. Owocki, Marc Gagné, Simon Daley-Yates

Earth & Space Sciences Faculty Publications

We present results from new self-consistent 3D magnetohydrodynamics(MHD)simulations of the magnetospheres from massive stars with a dipole magnetic axis that has a non-zero obliquity angle (β) to the star’s rotation axis. As an initial direct application, we compare the global structure of co-rotating discs for nearly aligned (β = 5◦) versus half-oblique (β = 45◦) models, both with moderately rapid rotation (∼0.5 critical). We find that accumulation surfaces broadly resemble the forms predicted by the analytical rigidly rotating magnetosphere model, but the mass buildup to near the critical level for centrifugal breakout against magnetic confinement distorts the field from the …

Three- And Four-Point Functions In Cpt -Even Lorentz-Violating Scalar Qed, Brett Altschul, L. C.T. Brito, J. C.C. Felipe, S. Karki, A. C. Lehum, A. Yu Petrov

Faculty Publications

The renormalization of quantum field theories usually assumes Lorentz and gauge symmetries, besides the general restrictions imposed by unitarity and causality. However, the set of renormalizable theories can be enlarged by relaxing some of these assumptions. In this work, we consider the particular case of a CPT-preserving but Lorentz-breaking extension of scalar QED. For this theory, we calculate the one-loop radiative corrections to the three- and four-point scalar-vector vertex functions, at the lowest order in the Lorentz-violation parameters, and we explicitly verify that the resulting low-energy effective action is compatible with the usual gauge invariance requirements. With these results, we …

Periodicities And Plasma Density Structure Of Jupiter’S Dawnside Magnetosphere, Xuanye Ma, A.A. Schok, P.A. Delamere, B. Mino, P.A. Damiano, B. Zhang, A. Sciola

Publications

The ability to quantify variations in magnetic field topology and density within Jupiter’s magnetosphere is an important step in understanding the overall structure and dynamics. The Juno spacecraft has provided a rich data set in the dawnside magnetosphere. The recent Grid Agnostic MHD for Extended Research Applications (GAMERA) global simulation study by Zhang et al. (2021) showed a highly structured plasmadisc with closed magnetic field lines mapping between the outer dawn-tail flank and the high latitude polar region. To test these model predictions, we examined Juno’s magnetic field data and electron/energetic particle data to categorize portions of orbits 1-15 into …

Staerkel Planetarium Introduces A New Round Of Speakers, Erik Johnson

Natural Science Faculty

Each year, the Staerkel Planetarium at Parkland College hosts speakers from around the world of science. The first lecturer of this series was the late professor Jim Kaler. After providing beloved astronomy talks for thirty years, the James Kaler Science Lecture Series was renamed in his honor.

Looking For Life, Conor C. Grubb

CAFE Symposium 2023

The topic of aliens is not just about conspiracy theories and tinfoil hats, through the years numerous respected scientists have weighed in and put thought into the topic. The Search for Extraterrestrial Intelligence (SETI) is closely tied to the Fermi Paradox and the Drake Equation. The Fermi Paradox considers why humans haven't already interacted with aliens if they exist, and the Drake Equation outlines potential variables that would influence the chances of humanity receiving radio contact from an alien civilization.

Measurement Of The VE- Nucleus Charged-Current Double-Differential Cross Section At 〈EV⟩ = 2.4 Gev Using Nova, M. A. Acero, P. Adamson, L. Aliaga, N. Anfimov, A. Antoshkin, E. Arrieta-Diaz, L. Asquith, A. Aurisano, A. Back, M. Biard, N. Balashov, P. Baldi, B. A. Bambah, S. Bashar, K. Bays, R. Bernstein, V. Bhatnagar, D. Bhattarai, B. Bhuyan, J. Bian, Roberto Petti, Et. Al.

Faculty Publications

The inclusive electron neutrino charged-current cross section is measured in the NOvA near detector using 8.02×10²⁰ protons-on-target in the NuMI beam. The sample of GeV electron neutrino interactions is the largest analyzed to date and is limited by ≃17% systematic rather than the ≃7.4% statistical uncertainties. The double-differential cross section in final-state electron energy and angle is presented for the first time, together with the single-differential dependence on Q² (squared four-momentum transfer) and energy, in the range 1  GeV≤E_νGENIE, GiBUU, NEUT, and NuWro neutrino event generators. The data do not strongly favor a model over the …

Galfit-Ing Agn Host Galaxies In Cosmos: Hst Versus Subaru, Callum Dewsnap, Pauline Barmby, Sarah C. Gallagher, C. Megan Urry, Aritra Ghosh, Meredith C. Powell

Physics and Astronomy Publications

The COSMOS field has been extensively observed by most major telescopes, including Chandra, HST, and Subaru. HST imaging boasts very high spatial resolution and is used extensively in morphological studies of distant galaxies. Subaru provides lower spatial resolution imaging than HST but a substantially wider field of view with greater sensitivity. Both telescopes provide near-infrared imaging of COSMOS. Successful morphological fitting of Subaru data would allow us to measure morphologies of over 104 known active galactic nucleus (AGN) hosts, accessible through Subaru wide-field surveys, currently not covered by HST. The morphological parameters indicate the types of galaxies that host AGNs. …

The Giant Accreting Protoplanet Survey (Gaplanets): Optimization Techniques For Robust Detections Of Protoplanets, Jéa I. Adams Redai, Katherine B. Follette, Jason Wang, Clare Leonard, William Balmer, Laird M. Close, Beck Dacus, Jared R. Males, Katie M. Morzinski, Joseph Palmo, Laurent Pueyo, Elijah Spiro, Helena Treiber, Kimberly Ward-Duong, Alex Watson

Astronomy: Faculty Publications

High-contrast imaging has afforded astronomers the opportunity to study light directly emitted by adolescent (tens of megayears) and “proto” (<10 >Myr) planets still undergoing formation. Direct detection of these planets is enabled by empirical point-spread function (PSF) modeling and removal algorithms. The computational intensity of such algorithms, as well as their multiplicity of tunable input parameters, has led to the prevalence of ad hoc optimization approaches to high-contrast imaging results. In this work, we present a new, systematic approach to optimization vetted using data of the high-contrast stellar companion HD 142527 B from the Magellan Adaptive Optics Giant Accreting Protoplanet …

Naming Venus: An Exploration Of Goddesses, Heroines, And Famous Women, Kavya Beheraj

Dissertations, Theses, and Capstone Projects

Humans have been observing and romanticizing Venus for more than 5,000 years. However, mapping its surface has nearly always been impossible, since the planet is shrouded in thick clouds. A breakthrough came just fifty years ago with the invention of radar imaging, leading to the discovery (and naming) of hundreds of new features in a relatively short length of time.

The rapid naming of Venus is a case study on the impact of planetary nomenclature — the process of naming features on other worlds. While the act of naming streamlines communication and humanizes alien landscapes, it is subject to bias, …

Floating Liquid Droplets On The Surface Of Cryogenic Liquids: Implications For Titan Rain, Kendra Farnsworth, Alejandro Soto, Vincent F. Chevrier, Jordan K. Steckloff, Jason M. Soderblom

Space and Planetary Science Faculty Publications and Presentations

Saturn’s moon, Titan, has a hydrocarbon-based hydrologic cycle with methane and ethane rainfall. Because of Titan’s low gravity, “floating liquid droplets” (coherent droplets of liquid hydrocarbons that float upon a liquid surface) may form on the surface of Titan’s hydrocarbon lakes and seas during rainfall. Floating liquid droplets, however, have not been investigated in the laboratory under conditions appropriate for the surface of Titan (cryogenic, hydrocarbon, liquids). We conducted a set of experiments to simulate methane and ethane rainfall under Titan surface conditions (89–94 K, 1.5 bar nitrogen atmosphere) and find that floating ethane droplets form in a wide range …

Wallaby Pilot Survey: H I Gas Kinematics Of Galaxy Pairs In Cluster Environment, Shin-Jeong Kim, Se-Heon Oh, Jing Wang, Lister Staveley-Smith, Bärbel S. Koribalski, Minsu Kim, Hye-Jin Park, Shinna Kim, Kristine Spekkens, Juan P. Madrid

Physics & Astronomy Faculty Publications

We examine the H I gas kinematics of galaxy pairs in two clusters and a group using Australian Square Kilometre Array Pathfinder (ASKAP) WALLABY pilot survey observations. We compare the H I properties of galaxy pair candidates in the Hydra I and Norma clusters, and the NGC 4636 group, with those of non-paired control galaxies selected in the same fields. We perform H I profile decomposition of the sample galaxies using a tool, BAYGAUD, which allows us to deblend a line-of-sight velocity profile with an optimal number of Gaussian components. We construct H I superprofiles of the sample galaxies via …

Modelling Strong Lenses From Wide-Field Ground-Based Observations In Kids And Gama, Shawn Knabel, Benne Holwerda, J Nightingale, T Treu, M Bilicki, S Brough, S Driver, L Finnerty, L Haberzettl, S Hegde, A M. Hopkins, K Kuijken, J Liske, A K. Pimblett, R C. Steele, A H. Wright

Faculty and Staff Scholarship

Despite the success of galaxy-scale strong gravitational lens studies with Hubble-quality imaging, a number of well-studied strong lenses remains small. As a result, robust comparisons of the lens models to theoretical predictions are difficult. This motivates our application of automated Bayesian lens modelling methods to observations from public data releases of overlapping large ground-based imaging and spectroscopic surveys: Kilo-Degree Survey (KiDS) and Galaxy and Mass Assembly (GAMA), respectively. We use the open-source lens modelling software PYAUTOLENS to perform our analysis. We demonstrate the feasibility of strong lens modelling with large-survey data at lower resolution as a complementary avenue to studies …

Effects Of Silicon Dioxide As The Polar Dielectric On The Infrared Absorption Spectrum Ofthemetal-Insulator-Metal Metasurface, Ahmad K. Jafari, Matthew Gaddy, Imtiaz Ahmad, Satya R. Kachiraju, M D. Borhan Mia, Ishtiaque Ahmed, Sergey Nikishin, Myoung-Hwan Kim, Ayrton A. Bernussi

Physics & Astronomy Faculty Publications

Metal-insulator-metal metasurfaces have been widely used as high-performance absorbers in almost all electromagnetic spectral ranges. Their absorption spectra can be engineered by making variations in the geometry of the unit cells and/or by embedding materials with specific optical constants. Including a polar dielectric in their structure is another approach for manipulating their absorption spectra. In this research, we have numerically and experimentally investigated the effect of using silicon dioxide (SiO2) as a polar dielectric on the absorption spectrum of a metal-insulator-metal metasurface composed of a tri-layer of Ni-SiO2-Ni. Our results have shown the presence of …

Measurement Of Near-Threshold Proton Branching Ratios In 31s Important For Novae, Sudarsan Balakrishnan

LSU Doctoral Dissertations

Classical novae are stellar explosions that contribute to the nucleosynthesis of isotopes on the proton-rich side of the valley of stability up to ⁴⁰Ca. In ONe novae, the incompletely understood reaction rate of ³⁰P(p,γ)³¹S is known to strongly influence the production rate of several stable isotopes such as ³⁰Si, ³¹P, and ^32,33,34S. A precise measurement of this reaction rate has several potential implications towards matching astrophysical observables to the physical composition of the nova site -- the observed elemental abundance ratios of O/S and S/Al have been suggested as useful `thermometers' to gauge …

Probing Massive Contact Binary Star Evolution Via Measurements Of Orbital Period Changes, Henry Phippen, Levi Carr, Larry A. Molnar

Summer Research

Many stars have companions orbiting so closely that they share a common atmosphere: contact binary stars (see Figure 1). High and low mass systems differ significantly in key observable properties such as mass ratio. In the accompanying poster (Carr et al. 2023), we show that considerations of dynamic and thermal stability prohibit nearly equal masses for low mass (sun-like) systems, but not for high mass systems. Menon et al. (2021) recently published models of the behavior of massive systems under the approximation that the internal structures of the stars are not affected by their being in contact. A key observable …

Advanced Thermoluminescence Spectroscopy As A Research Tool For Semiconductor And Photonic Materials: A Review And Perspective, Farida Selim

Physics and Astronomy Faculty Publications

Thermoluminescence (TL) or thermally stimulated luminescence (TSL) spectroscopy is based on liberating charge carriers from traps in the bandgap by providing enough thermal energy to overcome the potential barrier of the traps. It provides a powerful tool to measure the positions of the localized states/traps in the bandgap. Despite that, its applications in semiconductors are very limited. Herein, the basics of TL spectroscopy and the recent advances in the technique with focus on cryogenic thermally stimulated photoemission spectroscopy (C-TSPS) which extends TL measurements to cryogenic regime and allows the detection of very low concentrations of shallow and deep localized states …

The Final Step In Contact Binary Star Formation, Larry A. Molnar, Levi Carr, Henry Phippen

Summer Research

A binary star is a system that contains two stars orbiting each other. A contact binary is a binary star whose component stars are so close that they share the same atmosphere (see Figure 1). They are the most common kind of eclipsing binary stars. Critical questions we have answered are: how do they form, how do they survive for a long time, and how do they ultimately die?

Solar Cells, Lambert W And The Logwright Functions, Prabhat Lankireddy, Sibibalan Jeevanandam, Aditya Chaudhary, P. C. Deshmukh, Ken Roberts, S. R. Valluri

Physics and Astronomy Publications

Algorithms that calculate the current-voltage (I-V) characteristics of a solar cell play an important role in processes that aim to improve the efficiency of a solar cell. I-V characteristics can be obtained from different models used to represent the solar cell, and the single diode model is a simple yet accurate model for common field implementations. However, the I-V characteristics are obtained by solving implicit equations, which involve repeated iterations and inherent errors associated with numerical methods used. Some methods use the Lambert W function to get an exact explicit formula, but often causes numerical overflow problems. The present work …

Modelling Of Covid-19 Using Fractional Differential Equations, Rishi Patel, P. Sainani, M. Brar, R. Patel, X. Li, J. Drozd, F. A. Chishtie, A. Benterki, T. C. Scott, S. R. Valluri

Physics and Astronomy Publications

In this work, we have described the mathematical modeling of COVID-19 transmission using fractional differential equations. The mathematical modeling of infectious disease goes back to the 1760s when the famous mathematician Daniel Bernoulli used an elementary version of compartmental modeling to find the effectiveness of deliberate smallpox inoculation on life expectancy. We have used the well-known SIR (Susceptible, Infected and Recovered) model of Kermack & McKendrick to extend the analysis further by including exposure, quarantining, insusceptibility and deaths in a SEIQRDP model. Further, we have generalized this model by using the solutions of Fractional Differential Equations to test the accuracy …

The Role Of R-Modes In Pulsar Spindown, Pulsar Timing And Gravitational Waves, Varenya Upadhyaya, Xiyuan Li, Xiyang Zhang, S. R. Valluri

Physics and Astronomy Publications

Pulsars are fast spinning neutron stars that lose their rotational energy via various processes such as gravitational and magnetic radiation, particle acceleration and mass loss processes. This dissipation can be quantified by a spin-down equation that measures the rate of change of the frequency as a function of the rotational frequency itself. We explore the pulsar spin-down and consider the spin-down equation upto the seventh order in frequency. This seventh order term accounts for energy loss due to the gravitational radiation caused by a current type quadrupole in the pulsar due to r-modes. We derive the rotational frequency due to …