Astrophysics and Astronomy Commons^™

The Implementation Of A Fast-Folding Pipeline For Long-Period Pulsar Searching In The Palfa Survey, E. Parent, V. M. Kaspi, S. M. Ransom, M. Krasteva, C. Patel, P. Scholz, A. Brazier, M. A. Mclaughlin, Keeisi Caballero, Richard S. Camuccio

Physics & Astronomy Faculty Publications

The Pulsar Arecibo L-Band Feed Array (PALFA) survey, the most sensitive blind search for radio pulsars yet conducted, is ongoing at the Arecibo Observatory in Puerto Rico. The vast majority of the 180 pulsars discovered by PALFA have spin periods shorter than 2 s. Pulsar surveys may miss long-period radio pulsars owing to the summing of a finite number of harmonic components in conventional Fourier analyses (typically ∼16), or as a result of the strong effect of red noise at low modulation frequencies. We address this reduction in sensitivity by using a time-domain search technique: the fast-folding algorithm (FFA). We …

X-Rays From Magnetic B-Type Stars, Corinne Fletcher

Theses and Dissertations

Recent surveys have found that ∼10% of massive stars host strong, mostly dipolar magnetic fields with strengths on the order of a kilogauss. The prominent idea describing the interaction between the stellar winds and the magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the ionized wind material is forced to move along the closed magnetic field loops and collides at the magnetic equator, creating a shock (Δv ∼ 500−800 km s−1). As the shocked material cools radiatively, it will emit X-rays. Therefore, X-ray spectroscopy is a key tool in detecting and probing the wind material …

Galaxy And Mass Assembly (Gama): Variation In Galaxy Structure Across The Green Valley, Lee S. Kelvin, Malcolm N. Bremer, Steven Phillipps, Philip A. James, Luke J.M. Davies, Roberto De Propris, Amanda J. Moffett, Susan M. Percival, Ivan K. Baldry, Chris A. Collins, Mehmet Alpaslan, Joss Bland-Hawthorn, Sarah Brough, Michelle Cluver, Simon P. Driver, Abdolhosein Hashemizadeh, Benne W. Holwerda, Jarkko Laine, Maritza A. Lara-Lopez, Jochen Liske, Witold Maciejewski, Nicola R. Napolitano, Samantha J. Penny, Cristina C. Popescu, Anne E. Sansom, Will Sutherland, Edward N. Taylor, Eelco Van Kampen, Lingyu Wang

Faculty and Staff Scholarship

Using a sample of 472 local Universe (z < 0.06) galaxies in the stellar mass range 10.25 < logM*/M⊙ < 10.75, we explore the variation in galaxy structure as a function of morphology and galaxy colour. Our sample of galaxies is subdivided into red, green, and blue colour groups and into elliptical and non-elliptical (disk-type) morphologies. Using Kilo- Degree Survey (KiDS) and Visible and Infrared Survey Telescope for Astronomy (VISTA) Kilo-Degree Infrared Galaxy Survey (VIKING) derived postage stamp images, a group of eight volunteers visually classified bars, rings, morphological lenses, tidal streams, shells, and signs of merger activity for all systems. We find a significant surplus of rings (2.3s) and lenses (2.9s) in disk-type galaxies as they transition across the green valley. Combined, this implies a joint ring/lens green valley surplus significance of 3.3s relative to equivalent disk-types within either the blue cloud or the red sequence. We recover a bar fraction of ~44 per cent which remains flat with colour, however, we find that the presence of a bar acts to modulate the incidence of rings and (to a lesser extent) lenses, with rings in barred disk-type galaxies more common by ~20-30 percentage points relative to their unbarred counterparts, regardless of colour. Additionally, green valley disk-type galaxies with a bar exhibit a significant 3.0s surplus of lenses relative to their blue/red analogues. The existence of such structures rules out violent transformative events as the primary end-of-life evolutionary mechanism, with a more passive scenario the favoured candidate for the majority of galaxies rapidly transitioning across the green valley.

Use Of Phase And Amplitude Gradient Estimation For Acoustic Source Characterization And Localization, Joseph Scott Lawrence

Theses and Dissertations

Energy-based acoustic quantities provide vital information about acoustic fields and the characterization of acoustic sources. Recently, the phase and amplitude gradient estimator (PAGE) method has been developed to reduce error and extend bandwidth of energy-based quantity estimates. To inform uses and applications of the method, analytical and experimental characterizations of the method are presented. Analytical PAGE method bias errors are compared with those of traditional estimation for two- and three-microphone one-dimensional probes. For a monopole field when phase unwrapping is possible, zero bias error is achieved for active intensity using three-microphone PAGE and for specific acoustic impedance using two-microphone PAGE. …

A Wave From Einstein

DePaul Magazine

The discovery in 2015 of gravitational waves 100 years after Albert Einstein predicted their existence gave scientists a new way of understanding the universe. This discovery, made possible by decades of work and the collaborative efforts of astrophysicists around the world offers a window into how science advances. The concept of science as a way of knowing is discussed.

Broadband Measurement And Reduction Of Quantum Radiation Pressure Noise In The Audio Band, Jonathan Daniel Cripe

LSU Doctoral Dissertations

One hundred years after Albert Einstein predicted the existence of gravitational waves in his general theory of relativity, the Laser Interferometer Gravitational-Wave Observatory (LIGO) made the first direct detection of gravitational waves. Since the first detection of gravitational waves from a binary black hole merger, LIGO has gone on to detect gravitational waves from multiple binary black hole mergers, and more recently from a binary neutron star merger in collaboration with telescopes around the world. The detection of gravitational waves has opened a new window to the universe and has launched the era of gravitational wave astronomy.

With the first …

Neutrino Flavor Conversions In Dense Media, Lei Ma

Physics & Astronomy ETDs

Neutrinos are abundantly produced in astrophysical environments such as core-collapse supernovae and binary neutron star mergers. Neutrino flavor conversions in the dense media play important roles in the physical and chemical evolutions of the environments. In this dissertation, I study two mechanisms through which neutrinos may change their flavors.

In the first mechanism, neutrinos can experience flavor conversions through interactions with oscillatory perturbations in matter distributions. I show that this mechanism can be understood intuitively as Rabi oscillations. I also derive criteria which can be used to determine whether such parametric resonances exist in a given environment.

In the second …

Low Resolution Hi Imaging Of The Shield Galaxies, Masao L. Miazzo

Macalester Journal of Physics and Astronomy

We present low-resolution Karl G. Jansky Very Large Array D-configuration HI spectral line observations of 32 previously unobserved local-volume low-mass dwarf galaxies in the Survey of HI in Extremely Low-mass Dwarfs (SHIELD). SHIELD was designed to probe the physical characteristics of the objects that inhabit the faint end of the HI mass function as populated by the ALFALFA blind HI extragalactic survey. These low angular-resolution images localize the HI-gas and provide the first glimpse of the neutral interstellar medium in these sources. We quantify the total HI mass of each system, and, using SDSS imaging, we compare the HI and …

Modeling Recombination In Solar Cells, Paul Chery

Macalester Journal of Physics and Astronomy

Solar cells are a competitive alternative to nonrenewable energy sources such as fossil fuels. However, the efficiency of these devices is limited by photogenerated carrier recombination. We use a finite difference numerical model to study recombination phenomena in the absorber layer of solar cells including alternate recombination models and the effects of spatial distribution of recombination centers. We compare the effect of using the constant lifetime approximation for recombination to the full Shockley-Read-Hall expression in Silicon solar cells and find that the constant lifetime approximation holds for high defect densities but not for high photon flux densities. Finally, we simulate …

How Many Quasars Have Extremely High Velocity Outflows?, Carla P. Quintero, Sean S. Haas, Paola Rodriguez Hidalgo

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

No abstract provided.

Searching For A Connection Between Radio Emission And Uv/Optical Absorption In Quasars, Sean S. Haas, Carla P. Quintero, Paola Rodriguez Hidalgo

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

No abstract provided.

Direct Collapse To Supermassive Black Hole Seeds With Radiation Transfer: Cosmological Haloes, Kazem Ardaneh, Yang Luo, Isaac Shlosman, Kentaro Nagamine, John H. Wise, Michael C. Begelman

Physics and Astronomy Faculty Publications

We have modelled direct collapse of a primordial gas within dark matter haloes in the presence of radiative transfer, in high-resolution zoom-in simulations in a cosmological framework, down to the formation of the photosphere and the central object. Radiative transfer has been implemented in the flux-limited diffusion (FLD) approximation. Adiabatic models were run for comparison. We find that (a) the FLD flow forms an irregular central structure and does not exhibit fragmentation, contrary to adiabatic flow which forms a thick disc, driving a pair of spiral shocks, subject to Kelvin–Helmholtz shear instability forming fragments; (b) the …

Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary - Ii. Effect Of Binary And Disc Parameters, Rebecca G. Martin, Stephen H. Lubow

Physics & Astronomy Faculty Research

In a recent paper Martin & Lubow showed that a circumbinary disc around an eccentric binary can undergo damped nodal oscillations that lead to the polar (perpendicular) alignment of the disc relative to the binary orbit. The disc angular momentum vector aligns to the eccentricity vector of the binary. We explore the robustness of this mechanism for a low-mass disc (0.001 of the binary mass) and its dependence on system parameters by means of hydrodynamic disc simulations. We describe how the evolution depends upon the disc viscosity, temperature, size, binary mass ratio, orbital eccentricity, and inclination. We compare results with …

The Eccentric Cavity, Triple Rings, Two-Armed Spirals, And Double Clumps Of The Mwc 758 Disk, Ruobing Dong, Sheng-Yuan Liu, Josh Eisner, Sean Andrews, Jeffrey Fung, Zhauhuan Zhu, Eugene Chiang, Jun Hashimoto, Hauyu Baobab Liu, Simon Casassus, Thomas Esposito, Yasuhiro Hasegawa, Takayuki Muto, Yaroslav Pavlyuchenkov, David Wilner, Eiji Akiyama, Motohide Tamura, John Wisniewski

Physics & Astronomy Faculty Research

Spatially resolved structures in protoplanetary disks hint at unseen planets. Previous imaging observations of the transitional disk around MWC 758 revealed an inner cavity, a ring-like outer disk, emission clumps, and spiral arms, all possibly generated by companions. We present ALMA dust continuum observations of MWC 758 at 0.87 mm wavelength with 43 × 39 mas angular resolution (6.9 × 6.2 au) and 20 μJy beam−1 rms. The central submillimeter emission cavity is revealed to be eccentric; once deprojected, its outer edge can be well fitted by an ellipse with an eccentricity of 0.1 and one focus on the star. …

Young Blue Straggler Stars In The Galactic Field, Gemunu Ekanayake, Ronald Wilhelm

Physics and Astronomy Faculty Publications

In this study, we present an analysis of a sample of field blue straggler (BS) stars that show high ultra violet emission in their spectral energy distributions (SEDs): indication of a hot white dwarf (WD) companion to BS. Using photometry available in the Sloan Digital Sky Survey (SDSS) and Galaxy Evolution Explorer (GALEX) surveys, we identified 80 stars with ultraviolet (UV) excess. To determine the parameter distributions (mass, temperature, and age) of the WD companions, we developed a fitting routine that could fit binary model SEDs to the observed SED. Results from this fit indicate the need for a hot …

Global Climate And Atmospheric Composition Of The Ultra-Hot Jupiter Wasp-103b From Hst And Spitzer Phase Curve Observations, Laura Kreidberg, Michael R. Line, Vivien Parmentier, Kevin B. Stevenson, Tom Louden, Mickäel Bonnefoy, Jacqueline K. Faherty, Gregory W. Henry, Michael H. Williamson, Keivan Stassun, Thomas G. Beatty, Jacob L. Bean, Jonathan J. Fortney, Adam P. Showman, Jean-Michel Désert, Jacob Arcangeli

Information Systems and Engineering Management Research Publications

We present thermal phase curve measurements for the hot Jupiter WASP-103b observed with Hubble/WFC3 and Spitzer/IRAC. The phase curves have large amplitudes and negligible hotspot offsets, indicative of poor heat redistribution to the nightside. We fit the phase variation with a range of climate maps and find that a spherical harmonics model generally provides the best fit. The phase-resolved spectra are consistent with blackbodies in the WFC3 bandpass, with brightness temperatures ranging from 1880 ± 40 K on the nightside to 2930 ± 40 K on the dayside. The dayside spectrum has a significantly higher brightness temperature in the Spitzer …

How Middle Level Science Teachers Visualize And Translate Motion, Scale, And Geometric Space Of The Earth-Moon-Sun System With Their Students, Jennifer Wilhelm, Merryn Cole, Cheryl Cohen, Rebecca Lindell

Science, Technology, Engineering, and Mathematics (STEM) Education Faculty Publications

[This paper is part of the Focused Collection on Astronomy Education Research.] We examined teachers’ spatial-scientific reasoning and the alternative conceptions they held regarding Earth-space content. While participating in a professional development (PD) workshop, teachers engaged in an integrated mathematics and science project-based unit designed to foster spatial reasoning and improve lunar-related conceptual understanding. The Purdue Spatial Visualization Test-Rotation (PSVT-Rot) and the Lunar Phases Concept Inventory (LPCI) were used to assess understanding. We found the teachers held similar alternative conceptions as their students. Moreover, we discovered that teachers had limited understanding of the Earth-Moon-Sun scale, motions, and geometric configurations. To …

Spatial Thinking In Astronomy Education Research, Merryn Cole, Cheryl Cole, Jennifer Wilhelm, Rebecca Lindell

Science, Technology, Engineering, and Mathematics (STEM) Education Faculty Publications

This paper is part of the Focused Collection on Astronomy Education Research.] Multiple studies show that spatial thinking skills contribute to students’ performance in science, technology, engineering, and mathematics disciplines. The study of astronomy is no different with the understanding of many astronomical phenomena requiring spatial thinking skills. This paper describes traditional and contemporary approaches to characterizing and measuring spatial thinking skills and suggests how they inform research in astronomy education. It summarizes previous literature in astronomy education research and categorizes the research approaches of astronomy education peer-reviewed journal articles and conference proceedings that explicitly consider the role of spatial …

Mapping The Neutrino Floor For Direct Detection Experiments Based On Dark Matter-Electron Scattering, Jason Wyenberg, Ian M. Shoemaker

Faculty Work Comprehensive List

We study the discovery reach of future Dark Matter (DM) Direct Detection experiments using DM-electron scattering in the presence of the solar neutrino background. At these low energies traditional methods for nuclear and electronic recoil discrimination fail, implying that the neutrino- nucleusscattering background can be sizable. We calculate discovery limits based on ionization values of signal and background, and quantify the dependence on the ionization model. Moreover, we explore how the dependence of the DM cross section discovery limits varies with exposure, electronic/nuclear recoil discrimination, DM form factors, and DM astrophysical uncertainties.

The Origin Of The Prompt Emission For Short Grb 170817a: Photosphere Emission Or Synchrotron Emission?, Yan-Zhi Meng, Jin-Jun Geng, Bin-Bin Zhang, Jun-Jie Wei, Di Xiao, Liang-Duan Liu, He Gao, Xue-Feng Wu, En-Wei Liang, Yong-Feng Huang, Zi-Gao Dai, Bing Zhang

Physics & Astronomy Faculty Research

The first gravitational-wave event from the merger of a binary neutron star system (GW170817) was detected recently. The associated short gamma-ray burst (GRB 170817A) has a low isotropic luminosity (~1047 erg s−1) and a peak energy E p ~ 145 keV during the initial main emission between −0.3 and 0.4 s. The origin of this short GRB is still under debate, but a plausible interpretation is that it is due to the off-axis emission from a structured jet. We consider two possibilities. First, since the best-fit spectral model for the main pulse of GRB 170817A is a cutoff power law …

The Allowed Parameter Space Of A Long-Lived Neutron Star As The Merger Remnant Of Gw170817, Shunke Ai, He Gao, Zi-Gao Dai, Xue-Feng Wu, Ang Li, Bing Zhang, Mu-Zi Li

Physics & Astronomy Faculty Research

Due to the limited sensitivity of the current gravitational wave (GW) detectors, the central remnant of the binary neutron star (NS) merger associated with GW170817 remains an open question. In view of the relatively large total mass, it is generally proposed that the merger of GW170817 would lead to a short-lived hypermassive NS or directly produce a black hole (BH). There is no clear evidence to support or rule out a long-lived NS as the merger remnant. Here, we utilize the GW and electromagnetic (EM) signals to comprehensively investigate the parameter space that allows a long-lived NS to survive as …

On The Radio Detectability Of Circumplanetary Discs, Zhaohuan Zhu, Sean M. Andrews, Andrea Isella

Physics & Astronomy Faculty Research

Discs around young planets, so-called circumplanetary discs (CPDs), are essential for planet growth, satellite formation, and planet detection. We study the millimetre and centimetre emission from accreting CPDs by using the simple α disc model. We find that it is easier to detect CPDs at shorter radio wavelengths (e.g. λ ≲ 1 mm). For example, if the system is 140 pc away from us, deep observations (e.g. 5 h) at ALMA Band 7 (0.87 mm) are sensitive to as small as 0.03 lunar mass of dust in CPDs. If the CPD is around a Jupiter mass planet 20 au away …

Galaxy And Mass Assembly (Gama): Gas Fuelling Of Spiral Galaxies In The Local Universe Ii. - Direct Measurement Of The Dependencies On Redshift And Host Halo Mass Of Stellar Mass Growth In Central Disc Galaxies, M. W. Grootes, A. Dvornik, R. J. Laureijs, R. J. Tuffs, C. C. Popescu, A. S.G. Robotham, J. Liske, M. J.I. Brown, Benne W. Holwerda, L. Wang

Faculty and Staff Scholarship

We present a detailed analysis of the specific star formation rate-stellar mass (sSFR-M*) of z ≤ 0.13 disc central galaxies using a morphologically selected mass-complete sample (M* ≥ 109.5M⊙). Considering samples of grouped and ungrouped galaxies, we find the sSFR-M* relations of disc-dominated central galaxies to have no detectable dependence on host dark-matter halo (DMH) mass, even where weak-lensing measurements indicate a difference in halo mass of a factor ≳ 5.We further detect a gradual evolution of the sSFR-M* relation of non-grouped (field) central disc galaxies with redshift, even over a Δz ≈ 0.04 (≈5 × 108 yr) interval, while …

Automation And Enhancements To The Erau Oscom System Space Situational Awareness, Sergei Bilardi, Patrick Rupp, Yevgeniy Lischuk, Joseph Stroup

Beyond: Undergraduate Research Journal

OSCOM, Optical tracking and Spectral characterization of CubeSats for Operational Missions, is a system developed at Embry-Riddle Aeronautical University to produce time-resolved photometry of small satellites using commercial-off-the-shelf hardware. OSCOM has been able to observe resident space objects (RSOs) as small as CubeSats using a Celestron 11” RASA and a CMOS machine vision camera from Allied Vision. By obtaining photometric measurements of satellites, a light curve can be constructed and used to help determine satellite characteristics such as spin rate, satellite state, and even satellite attitude. To enhance the OSCOM system’s ability to observe small satellites, there is ongoing development …

Multiple Stellar Flybys Sculpting The Circumstellar Architecture In Rw Aurigae, J. E. Rodriguez, R. Loomis, S. Cabrit, T. H. Haworth, S. Facchini, C. Dougados, R. A. Booth, Eric L.N. Jensen, C. J. Clarke, K. G. Stassun, W. R. F. Dent, J. Pety

Physics & Astronomy Faculty Works

We present high-resolution ALMA Band 6 and 7 observations of the tidally disrupted protoplanetary disks of the RW Aurigae binary. Our observations reveal tidal streams in addition to the previously observed tidal arm around RW Aur A. The observed configuration of tidal streams surrounding RW Aur A and B is incompatible with a single star–disk tidal encounter, suggesting that the RW Aurigae system has undergone multiple flyby interactions. We also resolve the circumstellar disks around RW Aur A and B, with CO radii of 58 au and 38 au consistent with tidal truncation, and 2.5 times smaller dust emission radii. …

Grb 120729a: External Shock Origin For Both The Prompt Gamma-Ray Emission And Afterglow, Li-Ye Huang, Xiang-Gao Wang, Weikang Zheng, En-Wei Liang, Da-Bin Lin, Shi-Qing Zhong, Hai-Ming Zhang, Xiao-Li Huang, Alexi V. Filippenko, Bing Zhang

Physics & Astronomy Faculty Research

Gamma-ray burst (GRB) 120729A was detected by Swift/BAT and Fermi/GBM, and then rapidly observed by Swift/XRT, Swift/UVOT, and ground-based telescopes. It had a single long and smooth \gamma-ray emission pulse, which extends continuously to the X-rays. We report Lick/KAIT observations of the source, and make temporal and spectral joint fits of the multiwavelength light curves of GRB 120729A. It exhibits achromatic light-curve behavior, consistent with the predictions of the external shock model. The light curves are decomposed into four typical phases: onset bump (Phase I), normal decay (Phase II), shallow decay (Phase III), and post-jet break (Phase IV). The spectral …

Gamma-Ray Burst Jet Breaks Revisited, Xiang-Gao Wang, Bing Zhang, En-Wei Liang, Rui-Jing Liang, Da-Bin Lin, Jing Li, Long Li

Physics & Astronomy Faculty Research

Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow light curve allows a measurement of the jet opening angle and true energetics of GRBs. In this paper, we re-investigate this problem using a large sample of GRBs that have an optical jet break that is consistent with being achromatic in the X-ray band. Our sample includes 99 GRBs from 1997 February to 2015 March that have optical and, for Swift GRBs, X-ray light curves that are consistent with the jet …

Controlling The Hydrophilicity And Cohesion During Deposition Of Highly Oriented Type I Collagen Films: An Approach For Biomedical Applications, Karina Ambrock, Bernd Grohe, Silvia Mittler

Physics and Astronomy Publications

Using the Langmuir-Blodgett (LB) technology we have pioneered a straightforward and low-cost approach to fabricate highly oriented collagen in thin film format (thickness: ~20 nm, surface areas: 2.5 x ~6.0 cm). An important factor for the use of these films is their cohesion under various conditions. Film formation was studied by coating hydrophilic or hydrophobic glass substrates. The fresh or aged (2 ½ years, -18°C.) collagen solutions used for this purpose either contained collagen network-stabilizing agents (n-propanol or phosphate ions) or were prepared without these stabilizers. Film formation on the air/water interface was analyzed by pressure-area isotherms. Maximum surface pressures …

Gpi Spectra Of Hr 8799 C, D, And E From 1.5 To 2.4 Μm With Klip Forward Modeling, Alexandra Z. Greenbaum, Laurent Pueyo, Jean Baptiste Ruffio, Jason J. Wang, Robert J.De Rosa, Jonathan Aguilar, Julien Rameau, Travis Barman, Christian Marois, Mark S. Marley, Quinn Konopacky, Abhijith Rajan, Bruce Macintosh, Megan Ansdell, Pauline Arriaga, Vanessa P. Bailey, Joanna Bulger, Adam S. Burrows, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Gaspard Duchêne, Michael P. Fitzgerald, Katherine B. Follette, Benjamin Gerard, Stephen J. Goodsell, James R. Graham, Pascale Hibon, Li Wei Hung, Patrick Ingraham, Paul Kalas, James E. Larkin, Kimberly Ward-Duong, Et Al

Astronomy: Faculty Publications

We explore KLIP forward modeling spectral extraction on Gemini Planet Imager coronagraphic data of HR 8799, using PyKLIP, and show algorithm stability with varying KLIP parameters. We report new and re-reduced spectrophotometry of HR 8799 c, d, and e in the H and K bands. We discuss a strategy for choosing optimal KLIP PSF subtraction parameters by injecting simulated sources and recovering them over a range of parameters. The K1/K2 spectra for HR 8799 c and d are similar to previously published results from the same data set. We also present a K-band spectrum of HR 8799 e for the …

Orbital Characteristics Of The Subdwarf-B And F V Star Binary Ec 20117-4014 (=V4640 Sgr), Tomomi Otani, T. D. Oswalt, A. E. Lynas-Gray, D. Kilkenny, C. Koen, M. Amaral, R. Jordan

Aerospace, Physics, and Space Science Faculty Publications

Among the competing evolution theories for subdwarf-B (sdB) stars is the binary evolution scenario. EC 20117- 4014 (=V4640 Sgr) is a spectroscopic binary system consisting of a pulsating sdB star and a late F main-sequence companion; however, the period and the orbit semimajor axes have not been precisely determined. This paper presents orbital characteristics of the EC 20117-4014 binary system using 20 years of photometric data. Periodic observed minus calculated (O–C) variations were detected in the two highest-amplitude pulsations identified in the EC 20117-4014 power spectrum, indicating the binary system’s precise orbital period (P = 792.3 days) and the light-travel-time …