Astrophysics and Astronomy Commons^™

Measurements Of The 16c + 12c And 16c + 13c Fusion Cross Sections With Implications For Astrophysics, Ashley Ann Hood

LSU Doctoral Dissertations

The fusion of neutron-rich nuclei is of interest to nuclear astrophysics and nuclear structure. X-ray superbursts are powered by runaway thermonuclear burning deep inside of a neutron star, where heating from the pycnonuclear fusion of neutron-rich isotopes is an important heat source. Experimental measurements of fusion cross sections of neutron-rich isotopes have provided insights regarding nucleon transfer and nuclear structure properties affecting fusion. Recently, the ¹⁵C + ¹²C total fusion cross section was measured using a ¹⁵C beam produced by the in-flight beam production facility, which is part of the Argonne Tandem LINAC Accelerator System (ATLAS) at …

The Halo Mass Function Of Late-Type Galaxies From H I Kinematics, Pengfei Li, Stacy S. Mcgaugh

Faculty Scholarship

We present an empirical method to measure the halo mass function (HMF) of galaxies. We determine the relation between the H i line width from single-dish observations and the dark matter halo mass (M 200) inferred from rotation-curve fits in the Spitzer Photometry and Accurate Rotation Curves (SPARC) database, then we apply this relation to galaxies from the H i Parkes All Sky Survey (HIPASS) to derive the HMF. This empirical HMF is well fit by a Schechter function, and matches that expected in the Λ Cold Dark Matter (ΛCDM) model over the range 1010.5 < M 200 < 1012 M o˙. More massive halos must be poor in neutral gas to maintain consistency with the power law predicted by ΛCDM. We detect no discrepancy at low masses. The lowest halo mass probed by HIPASS, however, is just greater than the mass scale where the Local Group missing satellite problem sets in. The integrated mass density associated with the dark matter halos of H i-detected galaxies sums to Ωm,gal ≈ 0.03 over the probed mass range.

Using Natural Phenomena To Study The Ionosphere, Joseph Benjamin Malins

Physics & Astronomy ETDs

This dissertation explores novel techniques for observing the ionosphere using natural signals. The ionosphere is a region of plasma hundreds of kilometers above the Earth that affects communication and remote sensing applications across the world. Traditional techniques for observing the ionosphere involve using man made radio signals, either to reflect the signal at HF frequencies or to pass several signals through the ionosphere and compare the difference the ionosphere makes in the signals. However, such techniques are limited by the ability of equipment to produce these signals and by the numerous laws and regulations governing transmission of signals in the …

Realistic Sensitivity Curves For Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Joseph D. Romano, Tristan L. Smith

Physics & Astronomy Faculty Publications

We construct realistic sensitivity curves for pulsar timing array searches for gravitational waves, incorporating both red and white noise contributions to individual pulsar noise spectra, and the effect of fitting to a pulsar timing model. We demonstrate the method on both simulated pulsars and a realistic array consisting of a subset of NANOGrav pulsars used in recent analyses. A comparison between the results presented here and measured upper limit curves from actual analyses shows agreement to tens of percent. The resulting sensitivity curves can be used to assess the detectability of predicted gravitational-wave signals in the nanohertz frequency band in …

Evolution Of A Relativistic Electron Beam For Tracing Magnetospheric Field Lines, Andrew T. Powis, Peter Porazik, Michael Greklek-Mckeon, Kailas Amin, David Shaw, Igor D. Kaganovich, Jay R. Johnson, Ennio Sanchez

Faculty Publications

Tracing magnetic field-lines of the Earth's magnetosphere using beams of relativistic electrons will open up new insights into space weather and magnetospheric physics. Analytic models and a single-particle-motion code were used to explore the dynamics of an electron beam emitted from an orbiting satellite and propagating until impact with the Earth. The impact location of the beam on the upper atmosphere is strongly influenced by magnetospheric conditions, shifting up to several degrees in latitude between different phases of a simulated storm. The beam density cross-section evolves due to cyclotron motion of the beam centroid and oscillations of the beam envelope. …

Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena

Physics & Astronomy ETDs

Scattering from randomly rough surfaces is a well-established sub area of electrodynamics. There remains much to be done since each surface and optical processes that may occur in within the scattering medium, and countless other scenarios, is different. There are also illumination models that describe lighting in a scene on the macroscopic scale where geometrical optics can be considered adequate. Of particular interest for us is the intersection of the physical scattering theories and the illumination models. We present two contributions: 1) A minimum of two independent images are needed since any opaque surface can be uniquely specified in terms …

Secondary Infall In The Seyfert's Sextet: A Plausible Way Out Of The Short Crossing Time Paradox, Omar López-Cruz, Héctor Javier Ibarra-Medel, Sebastián F. Sánchez, Mark Birkinshaw, Christopher Añorve, Jorge K. Barrera-Ballesteros, Jesús Falcon-Barroso, Wayne A. Barkhouse, Juan P. Torres-Papaqui

Physics Faculty Publications

We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly available data to investigate the star formation histories of galaxies in the Seyfert's Sextet (SS; HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories, we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turnaround, initially gas-rich galaxies crossed for the first time, consuming …

High Power And Optomechanics In Advanced Ligo Detectors, Terra Christine Hardwick

LSU Doctoral Dissertations

In September 2015, a new era of astronomy began with the first direct detection of grav- itational waves from a binary black hole coalescence. The event was captured by the Laser Interferometer Gravitational-wave Observatory, comprised of two long-baseline interferometers, one in Livingston, LA and one in Hanford, WA. At the time of the first detection, the interferometers were part way through an upgrade to an advanced configuration and were operating with a strain sensitivity of just better than 10⁻²³/Hz^1/2 around 100Hz. The full Advanced LIGO design calls for sensitivity of a few parts in 10⁻²⁴/Hz …

Alpha Capture Reaction Rates For Nucleosynthesis Within An Ab Initio Framework, Alison Constance Dreyfuss

LSU Doctoral Dissertations

Clustering in nuclear systems has broad impacts on all phases of stellar burning, and plays a significant role in our understanding of nucleosynthesis, or how and where nuclei are produced in the universe. The role of alpha particles in particular is extremely important for nuclear astrophysics: ⁴He was one of the earliest elements produced in the Big Bang, it is one of the most abundant elements in the universe, and helium burning -- in particular, the triple-alpha process -- is one of the most important ``engines'' in stars. To better understand nucleosynthesis and stellar burning, then, it is important …

Magnetic Field Effect In The Fine-Structure Constant And Electron Dynamical Mass, Efrain J. Ferrer, A. Sanchez

Physics & Astronomy Faculty Publications

We investigate the effect of an applied constant and uniform magnetic field in the fine-structure constant of massive and massless QED. In massive QED, it is shown that a strong magnetic field removes the so called Landau pole and that the fine-structure constant becomes anisotropic having different values along and transverse to the field direction. Contrary to other results in the literature, we find that the anisotropic fine-structure constant always decreases with the field. We also study the effect of the running of the coupling constant with the magnetic field on the electron mass. We find that in both cases …

Millimeter-Wavelength Characterization Of The Co Emission Of Comets 174p/Echeclus, 29p/Schwassmann-Wachmann, And C/2016 R2 (Panstarrs), Kacper Wierzchos

USF Tampa Graduate Theses and Dissertations

Comets are fascinating minor solar system bodies. They contain some of the most pristine and unprocessed material found in the solar system. As a comet approaches the Sun it displays the characteristic cometary coma and tail. This is due to the release of volatile species through a variety of processes. In the present work I studied the carbon monoxide emission of three very unique comets; 174P/Echeclus, 29P/Schwassmann-Wachmann and C/2016 R2 (PanSTARRS) with different radio telescopes at millimeter wavelengths. After molecular hydrogen, carbon monoxide is the second most abundant molecule in the universe, and is also the most volatile of the …

Spatially Resolved Stellar Kinematics Of The Ultra-Diffuse Galaxy Dragonfly 44. Ii. Constraints On Fuzzy Dark Matter, Asher Wasserman, Pieter Van Dokkum, Aaron Romanowsky, Jean Brodie, Shany Danieli, Duncan Forbes, Roberto Abraham, Christopher Martin, Matt Matuszewski, Alexa Villaume, John Tamanas, Stefano Profumo

Faculty Publications

Given the absence of directly detected dark matter (DM) as weakly interacting massive particles, there is strong interest in the possibility that DM is an ultralight scalar field, here denoted as "fuzzy" DM. Ultra-diffuse galaxies, with the sizes of giant galaxies and the luminosities of dwarf galaxies, have a wide range of DM halo masses, thus providing new opportunities for exploring the connections between galaxies and their DM halos. Following up on new integral field unit spectroscopic observations and dynamics modeling of the DM-dominated ultra-diffuse galaxy Dragonfly 44 in the outskirts of the Coma Cluster, we present models of fuzzy …

Detection And Characterisation Of 54 Massive Companions With The Sophie Spectrograph: Seven New Brown Dwarfs And Constraints On The Brown Dwarf Desert, ‪Flavien Kiefer, Guillaume Hébrard, Johannes Sahlmann, Sérgio G. Sousa, Thierry Forveille, Nuno Santos, Michel Mayor, Magali Deleuil, Paul Anthony Wilson, Shweta Dalal, Rodrigo F. Díaz, Gregory W. Henry, Janis Hagelberg, Melissa J. Hobson, Olivier Demangeon, Vincent Bourrier, Xavier Delfosse, Luc Arnold, Nicola Astudillo-Defru, Jean-Luc Beuzit, Isabelle Boisse, Xavier Bonfils, Simon Borgniet, François Bouchy, B. Courcol, David Ehrenreich, Nathan Hara, Anne-Marie Lagrange, Christophe Lovis, Guillaume Montagnier, C. Moutou, Francesco Pepe, Christian Perrier, Javiera Rey, Alexandre Santerne, Damien Ségransan, Stephane Udry, Alfred Vidal-Madjar

Information Systems and Engineering Management Research Publications

Context. Brown dwarfs (BD) are substellar objects intermediate between planets and stars with masses of ~13–80 M_J. While isolated BDs are most likely produced by gravitational collapse in molecular clouds down to masses of a few M_J, a non-negligible fraction of low-mass companions might be formed through the planet-formation channel in protoplanetary discs. The upper mass limit of objects formed within discs is still observationally unknown, the main reason being the strong dearth of BD companions at orbital periods shorter than 10 yr, also known as the BD desert.

Aims. To address this question, we aim …

Milky Way Morphology, Laurence A. Marschall

Physics and Astronomy Faculty Publications

From our limited perspective—living on a planet that orbits one of several hundred billion stars inside the Milky Way—the detailed structure of our home galaxy is difficult to determine. It has long been recognized by astronomers as a typical spiral galaxy, one of countless flattened pinwheels of stars seen throughout the universe. By mapping the distances to more than 2,400 stars, scientists have now created, with unprecedented precision, a three-dimensional map that shows the Milky Way has a twisted shape. [excerpt]

Near-Resonance In A System Of Sub-Neptunes From Tess, S. N. Quinn, J. C. Becker, J. E. Rodriguez, S. Hadden, C. X. Huang, T. D. Morton, F. C. Adams, D. Armstrong, J. D. Eastman, J. Homer, S. R. Kane, J. J. Lissauer, J. D. Twicken, A. Vanderburg, R. Wittenmyer, G. R. Ricker, R. K. Vanderspek, D. W. Latham, S. Seager, J. N. Winn, J. M. Jenkins, E. Agol, K. Barkaoui, C. A. Beichman, F. Bouchy, L. G. Bouma, A. Burdanov, J. Campbell, R. Carlino, S. M. Cartwright, D. Charbonneau, J. L. Christiansen, D. Ciardi, K. A. Collins, K. I. Collins, D. M. Conti, I. J. M. Crossfield, T. Daylan, J. Dittmann, J. Doty, D. Dragomir, E. Ducrot, M. Gillon, A. Glidden, R. F. Goeke, E. J. Gonzales, K. G. Hełminiak, E. P. Horch, S. B. Howell, E. Jehin, Eric L.N. Jensen, J. F. Kielkopf, M. H. Kristiansen, N. Law, A. W. Mann, M. Marmier, R. A. Matson, E. Matthews, T. Mazeh, M. Mori, F. Murgas, C. Murray, N. Narita, L. D. Nielsen, G. Ottoni, E. Palle, R. Pawłaszek, F. Pepe, J. Pitogo De Leon, F. J. Pozuelos, H. M. Relles, J. E. Schlieder, D. Sebastian, D. Ségransan, A. Shporer, K. G. Stassun, M. Tamura, S. Udry, I. Waite, J. G. Winters, C. Ziegler

Physics & Astronomy Faculty Works

We report the Transiting Exoplanet Survey Satellite detection of a multi-planet system orbiting the V = 10.9 K0 dwarf TOI-125. We find evidence for up to five planets, with varying confidence. Three transit signals with high signal-to-noise ratio correspond to sub-Neptune-sized planets (2.76, 2.79, and 2.94 R_⊕), and we statistically validate the planetary nature of the two inner planets (P_b = 4.65 days, P_c = 9.15 days). With only two transits observed, we report the outer object (P_.03 = 19.98 days) as a planet candidate with high signal-to-noise ratio. We also detect a candidate transiting …

Kelt-24b: A 5mJ Planet On A 5.6 Day Well-Aligned Orbit Around The Young V = 8.3 F-Star Hd 93148, J. E. Rodriguez, J. D. Eastman, G. Zhou, S. N. Quinn, T. G. Beatty, K. Penev, M. C. Johnson, P. A. Cargile, D. W. Latham, A. Bieryla, K. A. Collins, C. D. Dressing, D. R. Ciardi, H. M. Relles, G. Murawski, T. Nishiumi, A. Yonehara, R. Ishimaru, F. Yoshida, J. Gregorio, M. B. Lund, D. J. Stevens, K. G. Stassun, B. S. Gaudi, K. D. Colón, J. Pepper, N. Narita, S. Awiphan, P. Chuanraksasat, P. Benni, R. Zambelli, L. H. Garrison, M. L. Wilson, M. A. Cornachione, S. X. Wang, J. Labadie-Bartz, R. Rodríguez, R. J. Siverd, X. Yao, D. Bayliss, P. Berlind, M. L. Calkins, J. L. Chirstiansen, David H. Cohen, D. M. Conti, I. A. Curtis, D. L. Depoy, G. A. Esquerdo, P. Evans, D. Feliz, B. J. Fulton, T. W.-S. Holoien, D. J. James, T. Jayasinghe, H. Jang-Condell, Eric L.N. Jensen, J. A. Johnson, M. D. Joner, S. Khakpash, J. F. Kielkopf, R. B. Kuhn, M. Manner, J. L. Marshall, K. K. Mcleod, N. Mccrady, T. E. Oberst, R. J. Oelkers, M. T. Penny, P. A. Reed, D. H. Sliski, B. J. Shappee, D. C. Stephens, C. Stockdale, T.-G. Tan, M. Trueblood, P. Trueblood, S. Villanueva Jr., R. A. Wittenmyer, J. T. Wright

Physics & Astronomy Faculty Works

We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V = 8.3 mag, K = 7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a T eff = ${6509}_{-49}^{+50}$ K, a mass of M * = ${1.460}_{-0.059}^{+0.055}$ M ⊙, a radius of R * = 1.506 ± 0.022 R ⊙, and an age of ${0.78}_{-0.42}^{+0.61}$ Gyr. Its planetary companion (KELT-24 b) has a radius of R P = 1.272 ± 0.021 R J and a mass of M P = ${5.18}_{-0.22}^{+0.21}$ M J, and from Doppler tomographic …

Toi-150b And Toi-163b: Two Transiting Hot Jupiters, One Eccentric And One Inflated, Revealed By Tess Near And At The Edge Of The Jwst Cvz, D. Kossakowski, N. Espinoza, R. Brahm, A. Jordán, T. Henning, F. Rojas, M. Kürster, P. Sarkis, M. Schlecker, F. J. Pozuelos, K. Barkaoui, E. Jehin, M. Gillon, E. Matthews, E. P. Horch, D. R. Ciardi, I. J. M. Crossfield, E. Gonzales, S. B. Howell, R. Matson, J. Schlieder, J. Jenkins, G. Ricker, S. Seager, J. N. Winn, J. Li, M. E. Rose, J. C. Smith, S. Dynes, E. Morgan, J. N. Villasenor, D. Charbonneau, T. Jaffe, L. Yu, G. Bakos, W. Bhatti, F. Bouchy, K. A. Collins, K. I. Collins, Z. Csubry, P. Evans, Eric L.N. Jensen, C. Lovis, M. Marmier, L. D. Nielsen, D. Osip, F. Pepe, H. M. Relles, D. Ségransan, A. Shporer, C. Stockdale, V. Suc, O. Turner, S. Udry

Physics & Astronomy Faculty Works

We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high-resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package juliet reveals that TOI-150b is a 1.254±0.016 RJ⁠, massive (⁠2.61+0.19−0.12 MJ⁠) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated (⁠RP = 1.478+0.022−0.029RJ⁠, MP = …

Dark Matter And No Dark Matter: On The Halo Mass Of Ngc 1052, Duncan Forbes, Adebusola Alabi, Jean Brodie, Aaron Romanowsky

Faculty Publications

The NGC 1052 group, and in particular the discovery of two ultra-diffuse galaxies with very low internal velocity dispersions, has been the subject of much attention recently. Here we present radial velocities for a sample of 77 globular clusters associated with NGC 1052 obtained on the Keck telescope. Their mean velocity and velocity dispersion are consistent with that of the host galaxy. Using a simple tracer mass estimator, we infer the enclosed dynamical mass and dark matter fraction of NGC 1052. Extrapolating our measurements with a Navarro–Frenk–White (NFW) mass profile we infer a total halo mass of 6.2(±0.2) × 1012 …

The Imprint Of Spiral Arms On The Galactic Rotation Curve, Stacy S. Mcgaugh

Faculty Scholarship

We discuss a model for the Milky Way obtained by fitting the observed terminal velocities with the radial acceleration relation. The resulting stellar surface density profile departs from a smooth exponential disk, having bumps and wiggles that correspond to massive spiral arms. These features are used to estimate the term for the logarithmic density gradient in the Jeans equation, which turn out to have exactly the right location and amplitude to reconcile the apparent discrepancy between the stellar rotation curve and that of the interstellar gas. This model also predicts a gradually declining rotation curve outside the solar circle with …

Relativistic Particle Beams As A Resource To Solve Outstanding Problems In Space Physics, Ennio R. Sanchez, Andrew T. Powis, Igor D. Kaganovich, Robert Marshall, Peter Porazik, Jay R. Johnson, Michael Greklek-Mckeon, Kailas S. Amin, David Shaw, Micale Nicolls

Faculty Publications

The Sun's connection with the Earth's magnetic field and atmosphere is carried out through the exchange of electromagnetic and mass flux and is regulated by a complex interconnection of processes. During space weather events, solar flares, or fast streams of solar atmosphere strongly disturb the Earth's environment. Often the electric currents that connect the different parts of the Sun-Earth system become unstable and explosively release the stored electromagnetic energy in one of the more dramatic expressions of space weather—the geomagnetic storm and substorm. Some aspects of the magnetosphere-ionosphere connection that generates auroral arcs during space weather events are well-known. However, …

Search For Gravitational-Wave Signals Associated With Gamma-Ray Bursts During The Second Observing Run Of Advanced Ligo And Advanced Virgo, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, W. H. Wang

Physics & Astronomy Faculty Publications

We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of z ≤ 1. We estimate 0.07–1.80 joint detections with Fermi-GBM per year for the 2019–20 …

Effect Of Galaxy Mergers On Star-Formation Rates, W. J. Pearson, L. Wang, M. Alpaslan, I. Baldry, M. Bilicki, M. J.I. Brown, M. W. Grootes, Benne W. Holwerda, T. D. Kitching, S. Kruk, F. F.S. Van Der Tak

Faculty and Staff Scholarship

Context. Galaxy mergers and interactions are an integral part of our basic understanding of how galaxies grow and evolve over time. However, the effect that galaxy mergers have on star-formation rates (SFRs) is contested, with observations of galaxy mergers showing reduced, enhanced, and highly enhanced star formation. Aims. We aim to determine the effect of galaxy mergers on the SFR of galaxies using statistically large samples of galaxies, totalling over 200 000, which is over a large redshift range from 0.0 to 4.0. Methods. We trained and used convolutional neural networks to create binary merger identifications (merger or non-merger) in …

Default Parallels: The Science Potential Of Jwst Parallel Observations During Tso Primary Observations, Benne W. Holwerda, Jonathan Fraine, Nelly Mouawad, Joanna S. Bridge

Faculty and Staff Scholarship

The James Webb Space Telescope (JWST) will observe several stars for long cumulative durations while pursuing exoplanets as primary science targets for both Guaranteed Time Observations (GTO) and very likely General Observer (GO) programs. Here we argue in favor of an automatic default parallel program to observe, e.g., using the F200W/F277W filters or grism of NIRCAM/NIRISS in order to find high redshift (z (Formula Presented) 10) galaxies, cool red/brown dwarf substellar objects, solar system objects, and observations of serendipitous planetary transits. We argue here the need for automated exploratory astrophysical observations with unused JWST instruments during these long-duration exoplanet observations. …

A Rotating Aperture Mask For Small Telescopes, Edward L. Foley

Master's Theses

Observing the dynamic interaction between stars and their close stellar neighbors is key to establishing the stars’ orbits, masses, and other properties. Our ability to visually discriminate nearby stars is limited by the power of our telescopes, posing a challenge to astronomers at small observatories that contribute to binary star surveys. Masks placed at the telescope aperture promise to augment the resolving power of telescopes of all sizes, but many of these masks must be manually and repetitively reoriented about the optical axis to achieve their full benefits. This paper introduces a design concept for a mask rotation mechanism that …

Exploring Planetary Surfaces With Remote Sensing, Donald R. Hood

LSU Doctoral Dissertations

Aside from Earth, Mars is the most well-explored planetary body in our solar system. Much has been learned about its geologic past including a history of volcanism, ice ages, and potentially long-lasting liquid water. Much of this knowledge of Mars comes from remote observations of the surface and atmosphere from Mars-orbiting satellites. Such remote observations remain the only way to examine the entirety of Mars’ surface as rovers and landers can only examine small areas. The chapters of this work cover three projects that explore the surface of Mars through a variety of remote sensing methods.

In chapter 1, Gamma-ray …

Nonideal Mhd Simulation Of Hl Tau Disk: Formation Of Rings, Xiao Hu, Zhaohuan Zhu, Satoshi Okuzumi, Xue-Ning Bai, Lile Wang, Kengo Tomida, James M. Stone

Physics & Astronomy Faculty Research

Recent high-resolution observations unveil ring structures in circumstellar disks. The origin of these rings has been widely investigated under various theoretical scenarios. In this work we perform global 3D nonideal MHD simulations including effects from both ohmic resistivity and ambipolar diffusion (AD) to model the HL Tau disk. The nonideal MHD diffusion profiles are calculated based on the global dust evolution calculation including sintering effects. Disk ionization structure changes dramatically across the snow line due to the change of dust size distribution close to the snow line of major volatiles. We find that accretion is mainly driven by disk wind. …

P-13 Astronomy From Ripples In Spacetime, Tiffany Summerscales

Celebration of Research and Creative Scholarship

The LIGO and Virgo detectors have made a total of 11 confirmed measurements of gravitational waves, the faint ripples in the fabric of spacetime predicted by Einstein’s theory of general relativity. Ten of these gravitational wave events were caused by the inspiral, collision, and merging of a pair of black holes and the remaining event by a pair of neutron stars. These measurements have helped us learn about the objects that produced the gravitational waves. Regular candidate detections are now shared in real time with both astronomers and the public.

Galaxy And Mass Assembly: A Comparison Between Galaxy-Galaxy Lens Searches In Kids/Gama, Shawn Knabel, Benne Holwerda

Posters-at-the-Capitol

Strong gravitational lenses are cases where a distant background galaxy is located directly behind a massive foreground galaxy, whose gravity causes the light from the background galaxy to bend around the foreground galaxy. In addition to being visually stunning, these rare events are useful laboratories for furthering our understanding of gravity and cosmology and to determine properties, such as the mass and dark matter content, of the lensing galaxies themselves. The trouble is finding enough of these strong gravitational lenses for further study. The immensity of the catalogs being collected by state-of-the-art telescopes requires equally innovative methods for interpreting that …

Star-Forming, Rotating Spheroidal Galaxies In The Gama And Sami Surveys, Amanda J. Moffett, Steven Phillipps, Aaron S.G. Robotham, Simon P. Driver, Malcolm N. Bremer, Luca Cortese, O. Ivy Wong, Sarah Brough, Michael J.I. Brown, Julia J. Bryant, Christopher J. Conselice, Scott M. Croom, Koshy George, Greg Goldstein, Michael Goodwin, Benne W. Holwerda, Andrew M. Hopkins, Iraklis S. Konstantopoulos, Jon S. Lawrence, Nuria P.F. Lorente, Anne M. Medling, Matt S. Owers, Kevin A. Pimbblet, Samuel N. Richards, Sarah M. Sweet, Jesse Van De Sande

Faculty and Staff Scholarship

The Galaxy And Mass Assembly (GAMA) survey has morphologically identified a class of 'Little Blue Spheroid' (LBS) galaxies whose relationship to other classes of galaxies we now examine in detail. Considering a sample of 868 LBSs, we find that such galaxies display similar but not identical colours, specific star formation rates, stellar population ages, massto- light ratios, and metallicities to Sd-Irr galaxies. We also find that LBSs typically occupy environments of even lower density than those of Sd-Irr galaxies, where ∼65 per cent of LBS galaxies live in isolation. Using deep, high-resolution imaging from VST KiDS and the new Bayesian, …

Pulsations, Eruptions, And Evolution Of Four Yellow Hypergiants, Arnout M. Van Genderen, Alex Lobel, Hans Nieuwenhuijzen, Gregory W. Henry, Cornelis De Jager, E. Blown, Giorgio Di Scala, Erwin J. Van Ballegoij

Information Systems and Engineering Management Research Publications

Aims. We aim to explore the variable photometric and stellar properties of four yellow hypergiants (YHGs), HR 8752, HR 5171A, ρ Cas, and HD 179821, and their pulsations of hundreds of days, and long-term variations (LTVs) of years. We also aim to explore light and colour curves for characteristics betraying evolutionary loops and eruptive episodes and to investigate trends of quasi-periods and the possible need for distance revisions.

Methods. We tackled multi-colour and visual photometric data sets, looked for photometric indications betraying eruptions or enhanced mass-loss episodes, calculated stellar properties mainly using a previously published temperature calibration, and investigated the …