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2020

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Articles 151 - 180 of 334

Full-Text Articles in Astrophysics and Astronomy

Towards Realism Interpretation Of Wave Mechanics Based On Maxwell Equations In Quaternion Space And Some Implications, Including Smarandache’S Hypothesis, Florentin Smarandache, Victor Christianto, Yunita Umniyati Jun 2020

Towards Realism Interpretation Of Wave Mechanics Based On Maxwell Equations In Quaternion Space And Some Implications, Including Smarandache’S Hypothesis, Florentin Smarandache, Victor Christianto, Yunita Umniyati

Branch Mathematics and Statistics Faculty and Staff Publications

No abstract provided.

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Hd 165054: An Astrometric Calibration Field For High-Contrast Imagers In Baade's Window, Meiji M. Nguyen, Robert J. De Rosa, Robert J. De Rosa, Jason J. Wang, Thomas M. Esposito, Paul Kalas, Paul Kalas, James R. Graham, Bruce Macintosh, Vanessa P. Bailey, Travis Barman, Joanna Bulger, Joanna Bulger, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Gaspard Duchêne, Gaspard Duchêne, Michael P. Fitzgerald, Katherine B. Follette, Benjamin L. Gerard, Benjamin L. Gerard, Stephen J. Goodsell, Alexandra Z. Greenbaum, Pascale Hibon, Justin Hom, Li Wei Hung, Patrick Ingraham, Quinn Konopacky, James E. Larkin, Jérôme Maire, Franck Marchis, Kimberly Ward-Duong, Et Al Jun 2020

Hd 165054: An Astrometric Calibration Field For High-Contrast Imagers In Baade's Window, Meiji M. Nguyen, Robert J. De Rosa, Robert J. De Rosa, Jason J. Wang, Thomas M. Esposito, Paul Kalas, Paul Kalas, James R. Graham, Bruce Macintosh, Vanessa P. Bailey, Travis Barman, Joanna Bulger, Joanna Bulger, Jeffrey Chilcote, Tara Cotten, Rene Doyon, Gaspard Duchêne, Gaspard Duchêne, Michael P. Fitzgerald, Katherine B. Follette, Benjamin L. Gerard, Benjamin L. Gerard, Stephen J. Goodsell, Alexandra Z. Greenbaum, Pascale Hibon, Justin Hom, Li Wei Hung, Patrick Ingraham, Quinn Konopacky, James E. Larkin, Jérôme Maire, Franck Marchis, Kimberly Ward-Duong, Et Al

Astronomy: Faculty Publications

We present a study of the HD 165054 astrometric calibration field that has been periodically observed with the Gemini Planet Imager (GPI). HD 165054 is a bright star within Baade's Window, a region of the galactic plane with relatively low extinction from interstellar dust. HD 165054 was selected as a calibrator target due to the high number density of stars within this region (?3 stars per square arcsecond with H < 22), necessary because of the small field of view of the GPI. Using nine epochs spanning over five years, we have fit a standard five-parameter astrometric model to the astrometry of seven background stars within close proximity to HD 165054 (? < 2?). We achieved a proper motion precision of ?0.3 mas yr-1 and constrained the parallax of each star to be ?1 mas. Our measured proper motions and parallax limits are consistent with the background stars being a part of the galactic bulge. Using these measurements, we find no evidence of any systematic trend of either the plate scale or the north angle offset of GPI between 2014 and 2019. We compared our model describing the motions of the seven background stars to observations of the same field in 2014 and 2018 obtained with Keck/NIRC2, an instrument with excellent astrometric calibration. We find that the predicted position of the background sources is consistent with that measured by NIRC2, within the uncertainties of the calibration of the two instruments. In the future, we will use this field as a standard astrometric calibrator for the upgrade of GPI and potentially for other high-contrast imagers.

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Requirements For Gravitational Collapse In Planetesimal Formation - The Impact Of Scales Set By Kelvin - Helmholtz And Nonlinear Streaming Instability, Konstantin Gerbig, Ruth A. Murray-Clay, Hubert Klahr, Hans Baehr Jun 2020

Requirements For Gravitational Collapse In Planetesimal Formation - The Impact Of Scales Set By Kelvin - Helmholtz And Nonlinear Streaming Instability, Konstantin Gerbig, Ruth A. Murray-Clay, Hubert Klahr, Hans Baehr

Physics & Astronomy Faculty Research

The formation of planetesimals is a challenging problem in planet formation theory. A prominent scenario for overcoming dust growth barriers is the gravitational collapse of locally over-dense regions, shown to robustly produce ~100 km–sized objects. Still, the conditions under which planetesimal formation occurs remain unclear. For collapse to proceed, the self-gravity of an over-density must overcome stellar tidal disruption on large scales and turbulent diffusion on small scales. Here, we relate the scales of streaming and Kelvin–Helmholtz instability (KHI), which both regulate particle densities on the scales of gravitational collapse, directly to planetesimal formation. We support our analytic findings by …

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Solar Radio Burst Type Ii And Iii With Half Wave Dipole Antenna, Mohd Pauzi Farah Aqilah Jun 2020

Solar Radio Burst Type Ii And Iii With Half Wave Dipole Antenna, Mohd Pauzi Farah Aqilah

Student Works (2020-2029)

An investigation into the physics of solar radio burst type II was done to understand the frequency gap between its fundamental and harmonic emissions that happen as aftershocks of Coronal Mass Ejection (CME). Up until now, the evolution of type II and its associated coronal wave still remain a mystery. Hazardous CME study upholds its fore coming danger to human and technology. This work also addresses the issue of the lack of spatial resolution of previous solar radio burst type II studies. An instrument produced by ETH Zürich namely the Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Spectrometers …

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The Right Stuff In Geospace: Using Mutual Coercion To Avoid An Inevitable Prison For Humanity, Sarah Louise Vollmer Jun 2020

The Right Stuff In Geospace: Using Mutual Coercion To Avoid An Inevitable Prison For Humanity, Sarah Louise Vollmer

St. Mary's Law Journal

Even though you cannot see it, catastrophe is brewing in near-Earth orbit. As a product of the Cold War, the legal regime governing geospace and beyond has presented mankind with a paradox. Though we are free to utilize space through peaceful means, the inability to appropriate space by any sovereign claim of right has triggered a modern-day tragedy of the commons, with the only restriction being the constraints of radio frequency interference. The destructive domino effect of space debris collisions threatens the invaluable communicative and scientific utility derived from satellites in geospace. International and domestic space jurisprudence encourage space debris …

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Collisional Formation Of Top-Shaped Asteroids And Implications For The Origins Of Ryugu And Bennu, P. Michel, R.-L. Ballouz, O. S. Barnouin, M. Jutzi, K. J. Walsh, B. H. May, C. Manzoni, D. C. Richardson, S. R. Schwartz, S. Sugita, S. Watanabe, H. Miyamoto, M. Hirabayashi, W. F. Bottke, Harold Connolly Jr., M. Yoshikawa, D. S. Lauretta May 2020

Collisional Formation Of Top-Shaped Asteroids And Implications For The Origins Of Ryugu And Bennu, P. Michel, R.-L. Ballouz, O. S. Barnouin, M. Jutzi, K. J. Walsh, B. H. May, C. Manzoni, D. C. Richardson, S. R. Schwartz, S. Sugita, S. Watanabe, H. Miyamoto, M. Hirabayashi, W. F. Bottke, Harold Connolly Jr., M. Yoshikawa, D. S. Lauretta

School of Earth & Environment Departmental Research

Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can …

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Symmetry Energy Of Super-Dense Neutron-Rich Matter From Integrating Barotropic Pressures In Neutron Stars And Heavy-Ion Reactions, Bao-An Li, Wen-Jie Xie May 2020

Symmetry Energy Of Super-Dense Neutron-Rich Matter From Integrating Barotropic Pressures In Neutron Stars And Heavy-Ion Reactions, Bao-An Li, Wen-Jie Xie

Faculty Publications

Within the minimum model of neutron stars (NS) consisting of neutrons, protons and electrons, a new approach is proposed for inferring the symmetry energy of super-dense neutron-rich nucleonic matter above twice the saturation density ρ0 of nuclear matter directly from integrating iteratively barotropic pressures in both neutron stars and heavy-ion reactions. Simultaneously, the proton fraction of NSs at β equilibrium is extracted as a function of baryon density from the same procedure. An application of this approach using the NS pressure from GW170817 and the pressure in cold symmetric nuclear matter (SNM) extracted earlier by analyzing nuclear collective flow data …

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A Mildly Relativistic Outflow From The Energentic, Fast-Rising Blue Optical Transient Css161010 In A Dwarf Galaxy, Deanne L. Coppejans, R. Margutti, G. Terreran, A. J. Nayana, E. R. Coughlin, T. Laskar, K. D. Alexander, M. Bietenholz, D. Caprioli, P. Chandra, M. R. Drout, D. Frederiks, C. Frohmaier, K. H. Hurley, C. S. Kochanek, M. Macleod, A. Meisner, P. E. Nugent, A. Ridnaia, D. J. Sand, D. Svinkin, C. Ward, S. Yang, A. Baldeschi, I. V. Chilingarian, Y. Dong, C. Esquivia, W. Fong, C. Guidorzi, P. Lundqvist, D. Milisavljevic May 2020

A Mildly Relativistic Outflow From The Energentic, Fast-Rising Blue Optical Transient Css161010 In A Dwarf Galaxy, Deanne L. Coppejans, R. Margutti, G. Terreran, A. J. Nayana, E. R. Coughlin, T. Laskar, K. D. Alexander, M. Bietenholz, D. Caprioli, P. Chandra, M. R. Drout, D. Frederiks, C. Frohmaier, K. H. Hurley, C. S. Kochanek, M. Macleod, A. Meisner, P. E. Nugent, A. Ridnaia, D. J. Sand, D. Svinkin, C. Ward, S. Yang, A. Baldeschi, I. V. Chilingarian, Y. Dong, C. Esquivia, W. Fong, C. Guidorzi, P. Lundqvist, D. Milisavljevic

Physics & Astronomy Faculty Research

We present X-ray and radio observations of the Fast Blue Optical Transient CRTS-CSS161010 J045834−081803 (CSS161010 hereafter) at t = 69–531 days. CSS161010 shows luminous X-ray (L x ~ 5 × 1039 erg s−1) and radio (L ν ~ 1029 erg s−1 Hz−1) emission. The radio emission peaked at ~100 days post-transient explosion and rapidly decayed. We interpret these observations in the context of synchrotron emission from an expanding blast wave. CSS161010 launched a mildly relativistic outflow with velocity Γβc ≥ 0.55c at ~100 days. This is faster than the non-relativistic AT 2018cow (Γβc ~ 0.1c) and closer to ZTF18abvkwla (Γβc …

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The Planetary Luminosity Problem: " Missing Planets" And The Observational Consequences Of Episodi Accretion, Sean D. Brittain, Joan R. Najita, Ruobing Dong, Zhaohuan Zhu May 2020

The Planetary Luminosity Problem: " Missing Planets" And The Observational Consequences Of Episodi Accretion, Sean D. Brittain, Joan R. Najita, Ruobing Dong, Zhaohuan Zhu

Physics & Astronomy Faculty Research

The high occurrence rates of spiral arms and large central clearings in protoplanetary disks, if interpreted as signposts of giant planets, indicate that gas giants commonly form as companions to young stars (Myr) at orbital separations of 10–300 au. However, attempts to directly image this giant planet population as companions to more mature stars (>10 Myr) have yielded few successes. This discrepancy could be explained if most giant planets form by "cold start," i.e., by radiating away much of their formation energy as they assemble their mass, rendering them faint enough to elude detection at later times. In that …

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Gw Ori: Interactions Between A Triple-Star System And Its Circumtriple Disk In Action, Jiaquig Bi, Nienke Van Der Marel, Ruobing Dong, Takayuki Muto, Rebecca G. Martin, Jeremy L. Smallwood, Jun Hashimoto, Hauyu Baobab Liu, Hideko Nomura, Yasuhiro Hasegawa, Michihiro Takami, Mihoko Konishi, Munetake Momose, Kazuhiro D. Kanagawa, Akimasa Kataoka, Tomohiro Ono, Michael L. Sitko, Sanemichi Z. Takahashi, Kengo Tomida, Takashi Tsukagoshi May 2020

Gw Ori: Interactions Between A Triple-Star System And Its Circumtriple Disk In Action, Jiaquig Bi, Nienke Van Der Marel, Ruobing Dong, Takayuki Muto, Rebecca G. Martin, Jeremy L. Smallwood, Jun Hashimoto, Hauyu Baobab Liu, Hideko Nomura, Yasuhiro Hasegawa, Michihiro Takami, Mihoko Konishi, Munetake Momose, Kazuhiro D. Kanagawa, Akimasa Kataoka, Tomohiro Ono, Michael L. Sitko, Sanemichi Z. Takahashi, Kengo Tomida, Takashi Tsukagoshi

Physics & Astronomy Faculty Research

GW Ori is a hierarchical triple system with a rare circumtriple disk. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of 1.3 mm dust continuum and 12CO J = 2 − 1 molecular gas emission of the disk. For the first time, we identify three dust rings in the GW Ori disk at ~46, 188, and 338 au, with estimated dust mass of 74, 168, and 245 Earth masses, respectively. To our knowledge, its outermost ring is the largest dust ring ever found in protoplanetary disks. We use visibility modeling of dust continuum to show that the disk has misaligned …

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Computational Astronomy: Classification Of Celestial Spectra Using Machine Learning Techniques, Gayatri Milind Hungund May 2020

Computational Astronomy: Classification Of Celestial Spectra Using Machine Learning Techniques, Gayatri Milind Hungund

Master's Projects

Lightyears beyond the Planet Earth there exist plenty of unknown and unexplored stars and Galaxies that need to be studied in order to support the Big Bang Theory and also make important astronomical discoveries in quest of knowing the unknown. Sophisticated devices and high-power computational resources are now deployed to make a positive effort towards data gathering and analysis. These devices produce massive amount of data from the astronomical surveys and the data is usually in terabytes or petabytes. It is exhaustive to process this data and determine the findings in short period of time. Many details can be missed …

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A Fast Radio Burst Discovered In Fast Drift Scan Survey, Weiwei Zhu, Di Li, Rui Luo, Chenchen Miao, Bing Zhang, Laura Spitler, Duncan Lorimer, Michael Kramer, David Champion, Youling Yue, Andrew Cameron, Marilyn Cruces, Ran Duan, Yi Feng, Jun Han, George Hobbs, Chenhui Niu, Jiarui Niu, Zhichen Pan, Lei Qian, Dai Shi, Ningyu Tang, Pei Wang, Hongfeng Wang, Mao Yuan, Lei Zhang, Xinxin Zhang, Shuyun Cao, Li Feng, Hengqian Gan, Long Gao May 2020

A Fast Radio Burst Discovered In Fast Drift Scan Survey, Weiwei Zhu, Di Li, Rui Luo, Chenchen Miao, Bing Zhang, Laura Spitler, Duncan Lorimer, Michael Kramer, David Champion, Youling Yue, Andrew Cameron, Marilyn Cruces, Ran Duan, Yi Feng, Jun Han, George Hobbs, Chenhui Niu, Jiarui Niu, Zhichen Pan, Lei Qian, Dai Shi, Ningyu Tang, Pei Wang, Hongfeng Wang, Mao Yuan, Lei Zhang, Xinxin Zhang, Shuyun Cao, Li Feng, Hengqian Gan, Long Gao

Physics & Astronomy Faculty Research

We report the discovery of a highly dispersed fast radio burst (FRB), FRB 181123, from an analysis of ~1500 hr of drift scan survey data taken using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulse has three distinct emission components, which vary with frequency across our 1.0–1.5 GHz observing band. We measure the peak flux density to be... (See full abstract in article).

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Cherenkov Gamma Ray Detectors On High-Energy-Density Systems, Kevin Daniel Meaney May 2020

Cherenkov Gamma Ray Detectors On High-Energy-Density Systems, Kevin Daniel Meaney

Physics & Astronomy ETDs

High energy density (HED) systems are some of the most extreme environments ever created by mankind. Systems with pressures greater than 1 MBar can only be created by a handful of devices on earth, often utilizing high intensity lasers or pulsed power machines. HED systems offer a view into an extreme form of matter only seen in stellar cores, supernovas and other powerful astrophysical systems. Creating HED systems on Earth offer the possibility, if the physics and technology can be matured, to one day create a fusion power plant. If a system is hot and dense enough, the fusion reaction …

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Supercdms: Energy Calibration Of A Ge Hv Particle Detector, Salamong Xiong, Vuk Mandic, Matthew Fritts, Nicholas Mast, Jacob Nelson May 2020

Supercdms: Energy Calibration Of A Ge Hv Particle Detector, Salamong Xiong, Vuk Mandic, Matthew Fritts, Nicholas Mast, Jacob Nelson

Macalester Journal of Physics and Astronomy

The goal of the SuperCDMS collaboration is to directly detect dark matter. Weakly Interacting Massive Particles (WIMPs) are potential candidates. To detect WIMPs, it is important to be able to predict how a Ge/Si particle detector will respond to a dark matter signal. In particular, it is necessary to calibrate the recoil energy measured by these detectors. This paper presents evidence for dark matter, a description of the detector operation, and procedures used to analyze measured data from a SuperCDMS-HV Ge particle detector using Am-241 and a PuBe neutron source. Due to high event rate, criteria were developed to remove …

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The Leoncino Dwarf: A Neutral Hydrogen Analysis Of Agc 198691 And Its Extremely Metal-Poor Environment, Tylyn Page May 2020

The Leoncino Dwarf: A Neutral Hydrogen Analysis Of Agc 198691 And Its Extremely Metal-Poor Environment, Tylyn Page

Macalester Journal of Physics and Astronomy

Studies of low-mass galaxies are important for populating the low-mass ends of funda- mental physical relations. Extremely metal-poor (XMP) galaxies are low-mass galaxies with gas-phase oxygen abundances of 12+log(O/H) ≤ 7.35 ( 1/20 Z⊙), and are especially interesting as proxies for studying the distant past, as their chemical makeup resembles those of galaxies in the early universe. AGC 198691, referred to as the Leoncino Dwarf, was discovered through the Arecibo Legacy Fast ALFA (ALFALFA) survey and found to have an oxygen abundance of less than 3% Z⊙. Presented here are the results of recent Karl G. Jansky Very Large Array …

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Large Scale Grid Integration Of Wind And Solar Power With Storage, Nicholas Moore May 2020

Large Scale Grid Integration Of Wind And Solar Power With Storage, Nicholas Moore

Macalester Journal of Physics and Astronomy

The current energy grid in the United States is dominated by carbon intense energy generation methods that are based on production when and where it is required. However, solar and wind power have proved themselves as the most promising carbon free energy generation sources. Due to the unpredictable and uncontrollable nature of energy production from solar and wind, large scale integration of these resources into the electric grid will require robust storage capacity. In this project, we model the energy grid of the Midcontinent Independent System Operator (MISO) energy region with high concentrations of solar and wind power to analyze …

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Probing The Magnetic Fields In Cosmic Web Filaments, Andrew L. Mizener May 2020

Probing The Magnetic Fields In Cosmic Web Filaments, Andrew L. Mizener

Macalester Journal of Physics and Astronomy

We present a project to constrain the properties of magnetic fields in Cosmic Web filaments. We first perform rotation measure (RM) synthesis on 24 S-band Karl G Jansky Very Large Array (VLA) observations of moderate-redshift active galactic nuclei (AGN). These observations are combined with an existing catalog of Cosmic Web filaments in order to determine the number of filaments a given sight-line passes near or through. By tracking how observables such as rotation measure and polarization fraction change as a function of the number of intervening cosmic web filaments, we take the first steps towards providing observational constraints on the …

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Shape Model Of Potentially Hazardous Asteroid 1981 Midas From Radar And Lightcurve Observations, Riley Mcglasson May 2020

Shape Model Of Potentially Hazardous Asteroid 1981 Midas From Radar And Lightcurve Observations, Riley Mcglasson

Macalester Journal of Physics and Astronomy

We report observations of potentially hazardous, Apollo-class asteroid 1981 Midas, which passed 0.090 au from Earth (35 lunar distances) on March 21, 2018. During this close approach, Midas was observed by radar both from the Arecibo Observatory on March 21 through 25 (five nights), and from NASA's Goldstone Deep Space Communications Complex on March 19 and 21. These radar observations yielded one-dimensional continuous-wave spectra and two-dimensional delay-Doppler images. In addition, there have been optical lightcurve observations of Midas during four apparitions (1987, 1992, 2004, and 2018), which showed a rotation period of 5.22 hours. Midas has an absolute magnitude of …

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A Search For Pulsars Towards The Galactic Center, Jacob W. Hetrick, Kunal Mooley, Preshanth Jagannathan May 2020

A Search For Pulsars Towards The Galactic Center, Jacob W. Hetrick, Kunal Mooley, Preshanth Jagannathan

Macalester Journal of Physics and Astronomy

We present observations from two separate methods for observing the Galactic Center in an attempt to characterize its pulsar and neutron star populations. A persistent puzzle of the past 20 years has been the lack of pulsar detections towards the Galactic Center, specifically within a few parsecs of the central supermassive black hole Sgr A*. This object is bright in the total intensity of its polarized emission, but is very weakly linearly polarized. We take advantage of these circumstances in an experimental search technique where we utilize the Faraday effect in an attempt to detect high rotation measure (RM) point …

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Modeling Scavenging For A Hydraulic Free-Piston Engine, Nathan Davies May 2020

Modeling Scavenging For A Hydraulic Free-Piston Engine, Nathan Davies

Macalester Journal of Physics and Astronomy

The hydraulic free-piston engine at the University of Minnesota offers a solution to improve the hydraulic efficiency and reduce emission output of off-road vehicles. We developed a MATLAB Simulink model to track the pressure, temperature, and mass profile of the fuel within the cylinder during operation. By varying different initial conditions of our model, we found that a higher intake manifold pressure and larger bottom dead center location results in higher scavenging efficiency. These results can be used to improve the controller of this engine and better maintain stable operation.

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Band Extension And Possible Ridge Compression On Europa, Sarah Chinski May 2020

Band Extension And Possible Ridge Compression On Europa, Sarah Chinski

Macalester Journal of Physics and Astronomy

Jupiter's icy moon Europa has captivated and perplexed the scientific community since the discovery of its global liquid water ocean. Over the course of several missions to the Jovian system, high-resolution observations of Europa have determined that there are spreading zones where new crust is created, similar to the mid-ocean spreading tectonic process we observe on Earth. These features, known as bands, have symmetric hills and valleys, indicating brief events of activity where material from the interior is exuded through a central crack, and solidifies on both sides, creating two positive topography. Recently, Europan scientists have been questioning how these …

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Electrical Measurement Of Sram Cell Variation And Sensitivity To Singe-Event Upsets By Low-Energy Protons, James M. Cannon May 2020

Electrical Measurement Of Sram Cell Variation And Sensitivity To Singe-Event Upsets By Low-Energy Protons, James M. Cannon

Macalester Journal of Physics and Astronomy

With the rise of the transistor in the 1970s, electronics shifted from analog circuitry, where values are stored on a continuum, to digital, in which ones and zeros are the law of the land. Transistors, as a class circuit element, can be affected by radiation and cosmic rays which then cause temporary or permanent failures, depending on the specifics of the situation. On Earth, this poses little risk with all electronics shielded by the magnetosphere, however for space bound electronics, the risks from these extraterrestrial particles are not so negligible. The first step in designing a mission to be able …

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Design And Modal Analysis Of An Ultra-Wideband Receiver For Green Bank Observatory, Alyssa Bulatek May 2020

Design And Modal Analysis Of An Ultra-Wideband Receiver For Green Bank Observatory, Alyssa Bulatek

Macalester Journal of Physics and Astronomy

The next generation of radio receivers for astronomy will be marked by tenfold improvements in sensitivity. These sensitive receivers will be useful for the detection of broadband fast radio bursts and other transients as well as the efficient discovery of radio recombination lines among many other scientific pursuits. One contribution to these improvements is an increase to decade receiver bandwidths. The Green Bank Observatory (GBO) is currently in the process of fabricating a new ultra-wideband (UWB; 0.7 to 4.2 GHz) receiver for the Green Bank Telescope (GBT). The UWB receiver will be used by the North American Nanohertz Observatory for …

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Alfalfa Harvest: Hi Imaging And 3d Modeling Of Candidate Local Group Dwarf Galaxies, Lilly Bralts-Kelly, Susie Paine, Elizabeth A. K. Adams, John M. Cannon May 2020

Alfalfa Harvest: Hi Imaging And 3d Modeling Of Candidate Local Group Dwarf Galaxies, Lilly Bralts-Kelly, Susie Paine, Elizabeth A. K. Adams, John M. Cannon

Macalester Journal of Physics and Astronomy

Isolated neutral hydrogen (HI) clouds, or "ultra-compact high-velocity clouds" (UCHVCs), form a small subset of detections by the Arecibo Legacy Fast ALFA (ALFALFA) blind extragalactic survey. These systems, if located within ~1 Mpc, would populate the lowest-mass end of the HI mass function. Subsequent optical imaging has revealed that some of these UCHVCs harbor associated (thought sparse) stellar populations, suggesting that they may be some of the most extreme galaxies known in the Local Volume, with properties akin to ultra-faint dwarf galaxies but with significant neutral gas reservoirs. In this work, we investigate the neutral hydrogen properties of six UCHVC …

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Leoncino And Ugc 5186, Josh Bartz May 2020

Leoncino And Ugc 5186, Josh Bartz

Macalester Journal of Physics and Astronomy

AGC 198691 is commonly known as the Leoncino Dwarf and is one of the most metal poor galax- ies known. An Arecibo observation in 2011 first suggested that Leoncino could be gravitationally interacting with its neighbor UGC 5186. In this paper new VLA data is used to examine the H I com- ponent of both galaxies to determine their gravitational relationship. Although the VLA could not confirm intragalactic gas seen by Aricebo, the H I density and velocity components are strong indirect evidence of gravitational interaction. UGC 5186 has a large gaseous arm reaching in the direction of Leoncino. Additionally …

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Congressional Committee Resources On Space Policy During The 115th Congress (2017-2018): Providing Context And Insight Into Us Government Space Policy, Bert Chapman May 2020

Congressional Committee Resources On Space Policy During The 115th Congress (2017-2018): Providing Context And Insight Into Us Government Space Policy, Bert Chapman

Libraries Faculty and Staff Presentations

Article 1 of the US Constitution assigns the US Congress numerous responsibilities. These include creating new laws, revising existing laws, funding government programs, and conducting oversight of these programs' performance. Oversight of US Government agency space policy programs is executed by various congressional space policy committees including the House and Senate Science Committees, Armed Services, and Appropriations Committees. These committees conduct many public hearings on space policy, which invite expert witnesses to testify on US space policy programs and feature debate on the strengths and weaknesses of these programs. Documentation produced by these committees is widely available to the public, …

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Is Grb 110715a The Progenitor Of Frb 171209?, Xiang-Gao Wang, Long Li, Yuan-Pei Yang, Jia-Wei Luo, Bing Zhang, Da-Bin Lin, En-Wei Liang, Song-Mei Qin May 2020

Is Grb 110715a The Progenitor Of Frb 171209?, Xiang-Gao Wang, Long Li, Yuan-Pei Yang, Jia-Wei Luo, Bing Zhang, Da-Bin Lin, En-Wei Liang, Song-Mei Qin

Physics & Astronomy Faculty Research

The physical origin of fast radio bursts (FRBs) is unknown. Young magnetars born from gamma-ray bursts (GRBs) have been suggested as a possible central engine of FRBs. We test such a hypothesis by systematically searching for GRB–FRB spatial associations from 110 FRBs and 1440 GRBs. We find that one FRB event discovered by the Parkes telescope, FRB 171209, is spatially coincident with a historical long-duration GRB 110715A at z = 0.82. The afterglow of GRB 110715A is consistent with being powered by a millisecond magnetar. The extragalactic dispersion measure of FRB 171209 is in excess of that contributed by the …

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Absolute Dimensions Of The Unevolved F-Type Eclipsing Binary Bt Vulpeculae, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Matthew W. Muterspaugh May 2020

Absolute Dimensions Of The Unevolved F-Type Eclipsing Binary Bt Vulpeculae, Guillermo Torres, Claud H. Sandberg Lacy, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

We report extensive differential V-band photometry and high-resolution spectroscopy for the 1.14 day, detached, double-lined eclipsing binary BT Vul (F0+F7). Our radial-velocity monitoring and light-curve analysis lead to absolute masses and radii of ${M}_{1}=1.5439\pm 0.0098\,{{ \mathcal M }}_{\odot }^{{\rm{N}}}$ and ${R}_{1}=1.536\pm 0.018\,{{ \mathcal R }}_{\odot }^{{\rm{N}}}$ for the primary, and ${M}_{2}=1.2196\pm 0.0080\,{{ \mathcal M }}_{\odot }^{{\rm{N}}}$ and ${R}_{2}=1.151\pm 0.029\,{{ \mathcal R }}_{\odot }^{{\rm{N}}}$ for the secondary. The effective temperatures are 7270 ± 150 K and 6260 ± 180 K, respectively. Both stars are rapid rotators, and the orbit is circular. A comparison with stellar evolution models from the MESA Isochrones …

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Water On Mars—A Literature Review, Mohammad Nazari-Sharabian, Mohammad Aghababei, Moses Karakouzian, Mehrdad Karami May 2020

Water On Mars—A Literature Review, Mohammad Nazari-Sharabian, Mohammad Aghababei, Moses Karakouzian, Mehrdad Karami

Civil and Environmental Engineering and Construction Faculty Research

To assess Mars’ potential for both harboring life and providing useable resources for future human exploration, it is of paramount importance to comprehend the water situation on the planet. Therefore, studies have been conducted to determine any evidence of past or present water existence on Mars. While the presence of abundant water on Mars very early in its history is widely accepted, on its modern form, only a fraction of this water can be found, as either ice or locked into the structure of Mars’ plentiful water-rich materials. Water on the planet is evaluated through various evidence such as rocks …

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Finding Strong Gravitational Lenses In The Desi Decam Legacy Survey, Xiaosheng Huang, Christopher Storfer, V. Ravi, A. Pilon, M. Domingo, D. J. Schlegel, S. Bailey, A. Dey, R. R. Gupta, D. Herrera, S. Juneau, M. Landriau, D. Lang, A. Meisner, J. Moustakas, A. D. Myers, E. F. Schlafly, F. Valdes, B. A. Weaver, J. Yang, C. Yèche May 2020

Finding Strong Gravitational Lenses In The Desi Decam Legacy Survey, Xiaosheng Huang, Christopher Storfer, V. Ravi, A. Pilon, M. Domingo, D. J. Schlegel, S. Bailey, A. Dey, R. R. Gupta, D. Herrera, S. Juneau, M. Landriau, D. Lang, A. Meisner, J. Moustakas, A. D. Myers, E. F. Schlafly, F. Valdes, B. A. Weaver, J. Yang, C. Yèche

Physics and Astronomy

We perform a semi-automated search for strong gravitational lensing systems in the 9000 deg2 Dark Energy Camera Legacy Survey (DECaLS), part of the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys. The combination of the depth and breadth of these surveys are unparalleled at this time, making them particularly suitable for discovering new strong gravitational lensing systems. We adopt the deep residual neural network architecture developed by Lanusse et al. for the purpose of finding strong lenses in photometric surveys. We compile a training sample that consists of known lensing systems in the Legacy Surveys and the Dark Energy Survey as …

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