Gravitational Wave Calibration Error For Supernovae Core Collapse,
2020
Embry-Riddle Aeronautical University
Gravitational Wave Calibration Error For Supernovae Core Collapse, Brad Ratto
Discovery Day - Prescott
The existence of gravitational waves reveals yet another method in which information is transmitted across the cosmos, bringing with it further insight into the inner workings of our universe. In order to detect such phenomena, we use ground based Laser Interferometers to measure the microscopic deformations in space-time and explore a new frontier in gravitational astronomy. However, such instrumentation also induces distortions in the gravitational waves henceforth diminishing the ability to extract accurate physical information. Moreover, the ability to extract a coherent signal amongst the noise remains an issue that requires constant improvement. The aim of this study is to …
Global 3d Radiation Magnetohydrodynamic Simulations For Fu Ori's Accretion Disc And Observational Signatures Of Magnetic Fields,
2020
University of Nevada, Las Vegas
Global 3d Radiation Magnetohydrodynamic Simulations For Fu Ori's Accretion Disc And Observational Signatures Of Magnetic Fields, Zhaohuan Zhu, Yan-Fei Jiang, James M. Stone
Physics & Astronomy Faculty Research
FU Ori is the prototype of FU Orionis systems that are outbursting protoplanetary discs. Magnetic fields in FU Ori’s accretion discs have previously been detected using spectropolarimetry observations for Zeeman effects. We carry out global radiation ideal MHD simulations to study FU Ori’s inner accretion disc. We find that (1) when the disc is threaded by vertical magnetic fields, most accretion occurs in the magnetically dominated atmosphere at z ∼ R, similar to the ‘surface accretion’ mechanism in previous locally isothermal MHD simulations. (2) A moderate disc wind is launched in the vertical field simulations with a terminal speed of …
Fast Radio Bursts As Strong Waves Interacting With The Ambient Medium,
2020
Yunnan University
Fast Radio Bursts As Strong Waves Interacting With The Ambient Medium, Yuan-Pei Yang, Bing Zhang
Physics & Astronomy Faculty Research
Fast radio bursts (FRBs) are mysterious radio transients whose physical origin is still unknown. Within a few astronomical units near an FRB source, the electric field of the electromagnetic wave is so large that the electron oscillation velocity becomes relativistic, which makes the classical Thomson scattering theory and the linear plasma theory invalid. We discuss FRBs as strong waves interacting with the ambient medium, in terms of both electron motion properties and plasma properties. Several novel features are identified. (1) The cross section of Thomson scattering is significantly enhanced for the scattering photons. (2) On the other hand, because of …
On The Frb Luminosity Function – – Ii. Event Rate Density,
2020
Peking University
On The Frb Luminosity Function – – Ii. Event Rate Density, Rui Luo, Yunpeng Men, Kejia Lee, Weiyang Wang, D. R. Lorimer, Bing Zhang
Physics & Astronomy Faculty Research
The luminosity function of Fast Radio Bursts (FRBs), defined as the event rate per unit cosmic co-moving volume per unit luminosity, may help to reveal the possible origins of FRBs and design the optimal searching strategy. With the Bayesian modelling, we measure the FRB luminosity function using 46 known FRBs. Our Bayesian framework self-consistently models the selection effects, including the survey sensitivity, the telescope beam response, and the electron distributions from Milky Way/ the host galaxy/ local environment of FRBs. Different from the previous companion paper, we pay attention to the FRB event rate density and model the event counts …
Sun-Like Stars Shed Light On Solar Climate Forcing,
2020
National Center for Atmospheric Research
Sun-Like Stars Shed Light On Solar Climate Forcing, Philip G. Judge, Ricky Egeland, Gregory W. Henry
Information Systems and Engineering Management Research Publications
Recently published precise stellar photometry of 72 Sun-like stars obtained at the Fairborn Observatory between 1993 and 2017 is used to set limits on the solar forcing of Earth's atmosphere of ±4.5 W m−2 since 1750. This compares with the +2.2 ± 1.1 W m−2 IPCC estimate for anthropogenic forcing. Three critical assumptions are made. In decreasing order of importance they are: (a) most of the brightness variations occur within the average time series length of ≈17 yr; (b) the Sun seen from the ecliptic behaves as an ensemble of middle-aged solar-like stars; and (c) narrowband photometry in the Strömgren …
Fast Radio Bursts From Interacting Binary Neutron Star Systems,
2020
University of Nevada, Las Vegas
Fast Radio Bursts From Interacting Binary Neutron Star Systems, Bing Zhang
Physics & Astronomy Faculty Research
Recent observations of repeating fast radio bursts (FRBs) suggest that some FRBs reside in an environment consistent with that of binary neutron star (BNS) mergers. The bursting rate for repeaters could be very high and the emission site is likely from a magnetosphere. We discuss a hypothesis of producing abundant repeating FRBs in BNS systems. Decades to centuries before a BNS system coalesces, the magnetospheres of the two neutron stars start to interact relentlessly. Abrupt magnetic reconnection accelerates particles, which emit coherent radio waves in bunches via curvature radiation. FRBs are detected as these bright radiation beams point toward Earth. …
Asteroid Belt Survival Through Stellar Evolution: Dependence On The Stellar Mass,
2020
University of Nevada, Las Vegas
Asteroid Belt Survival Through Stellar Evolution: Dependence On The Stellar Mass, Rebecca G. Martin, Mario Livio, Jeremy L. Smallwood, Cheng Chen
Physics & Astronomy Faculty Research
Polluted white dwarfs are generally accreting terrestrial-like material that may originate from a debris belt like the asteroid belt in the Solar system. ... See full text for complete abstract.
The Effects Of Disc Self-Gravity And Radiative Cooling On The Formation Of Gaps And Spirals By Young Planets,
2020
University of Nevada, Las Vegas
The Effects Of Disc Self-Gravity And Radiative Cooling On The Formation Of Gaps And Spirals By Young Planets, Shangjia Zhang, Zhaohuan Zhu
Physics & Astronomy Faculty Research
We have carried out 2D hydrodynamical simulations to study the effects of disc self-gravity and radiative cooling on the formation of gaps and spirals. (1) With disc self-gravity included, we find stronger, more tightly wound spirals and deeper gaps in more massive discs. The deeper gaps are due to the larger Angular Momentum Flux (AMF) of the waves excited in more massive discs, as expected from the linear theory. The position of the secondary gap does not change, provided that the disc is not extremely massive (Q ≳ 2). (2) With radiative cooling included, the excited spirals become monotonically more …
Effects Of Opacity Temperature Dependence On Radiatively Accelerated Clouds,
2020
Institute of Astronomy
Effects Of Opacity Temperature Dependence On Radiatively Accelerated Clouds, Sergei Dyda, Daniel Proga, Christopher S. Reynolds
Physics & Astronomy Faculty Research
We study how different opacity–temperature scalings affect the dynamical evolution of irradiated gas clouds using time-dependent radiation-hydrodynamics simulations. When clouds are optically thick, the bright side heats up and expands, accelerating the cloud via the rocket effect. Clouds that become more optically thick as they heat accelerate ∼35 per cent faster than clouds that become optically thin. An enhancement of ∼85 per cent in the acceleration can be achieved by having a broken power-law opacity profile, which allows the evaporating gas driving the cloud to become optically thin and not attenuate the driving radiation flux. We find that up to …
Fenderson, Julia Katharine (Squires), 1905-1989 (Sc 3500),
2020
Western Kentucky University
Fenderson, Julia Katharine (Squires), 1905-1989 (Sc 3500), Manuscripts & Folklife Archives
Manuscript Collection Finding Aids
Finding aid and scan (Click on "Additional Files" below) for Manuscripts Small Collection 3500. “The Viewing of Halley’s Comet: 1910-1986, A Personal Remembrance by Julia Squires Fenderson as told to Charles Arterburn,” a reminiscence by Mrs. Fenderson, of Culver City, California, of her viewings of Halley’s Comet: first with her father in 1910 at a Catholic mission in Albuquerque, New Mexico; and again in 1986, at the Santa Monica (California) College Planetarium. Includes an explanatory e-mail from Charles Arterburn.
Resolving The Fu Orionis System With Alma: Interacting Twin Disks?,
2020
Universidad de Santiago de Chile
Resolving The Fu Orionis System With Alma: Interacting Twin Disks?, Sebastian Perez, Antonio Hales, Hauyu Baobab Liu, Zhaohuan Zhu, Simon Casassus, Jonathan Williams, Alice Zurlo, Nicolas Cuello, Lucas Cieza, David Principe
Physics & Astronomy Faculty Research
FU Orionis objects are low-mass pre-main sequence stars characterized by dramatic outbursts several magnitudes in brightness. These outbursts are linked to episodic accretion events in which stars gain a significant portion of their mass. The physical processes behind these accretion events are not yet well understood. The archetypal FU Ori system, FU Orionis, is composed of two young stars with detected gas and dust emission. The continuum emitting regions have not been resolved until now. Here, we present 1.3 mm observations of the FU Ori binary system using the Atacama Large Millimeter/submillimeter Array. The disks are resolved at 40 mas …
On Possibility Of Binary Companion Of The Sun: A Serendipity Finding And Comparison With Uvs Model Of Solar System,
2020
University of New Mexico
On Possibility Of Binary Companion Of The Sun: A Serendipity Finding And Comparison With Uvs Model Of Solar System, Victor Christianto, Florentin Smarandache
Branch Mathematics and Statistics Faculty and Staff Publications
While we completely understood that a binary dwarf companion of the Sun has not been accepted by majority of astronomers, allow us to present some new arguments, along with our own serendipitous encounter with such a binary companion of the Sun. We hope that the present note will be found useful for further investigations, in relation to Planet Nine and such a dwarf star companion of the Sun (sometimes dubbed as Nemesis). Nonetheless, this article is not an exhaustive review of such dwarf companion star theories.
The Large Scale Behaviour In The Disk Of Δ Scorpii From 2000-2018,
2020
Western University
The Large Scale Behaviour In The Disk Of Δ Scorpii From 2000-2018, Mark W. Suffak, Carol E. Jones, Christopher Tycner, Gregory W. Henry, Alex Cavaliéri Carciofi, Bruno C. Mota, A. C. Rubio
Information Systems and Engineering Management Research Publications
We model the circumstellar disk of δ Sco using the 3-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large scale changes in the disk through the years 2000 to 2018, and to see if these changes can be attributed to the secondary star affecting the disk throughout its orbit. We determine our best-fitting models through matching simulated observations to actual Hα spectroscopy and V-band photometric observations. Our modelling results confirm previous findings that the disk of δ Sco was forming early in the century. We also find a period of disk dissipation when the companion is …
Stellar Nucleosynthesis: Direct Measurement Of The Neutron-Capture Cross Sections Of Stable Germanium Isotopes And Design Of A Next Generation Ion Trap For The Study Of Beta-Delayed Neutron Emission,
2020
Louisiana State University and Agricultural and Mechanical College
Stellar Nucleosynthesis: Direct Measurement Of The Neutron-Capture Cross Sections Of Stable Germanium Isotopes And Design Of A Next Generation Ion Trap For The Study Of Beta-Delayed Neutron Emission, Alexander Laminack
LSU Doctoral Dissertations
Knowledge of stellar nuclear reaction rates is critical to understanding the cosmic origins of the abundances of elements. In order to determine these reaction rates, accurate measurements of nuclear cross sections are needed. This thesis presents the results of an experiment to directly measure the neutron capture cross sections of 70-Ge, 72-Ge, 74-Ge, and 76-Ge. These measurements were performed at the Los Alamos Neutron Science CEnter (LANSCE) using the Detector for Advanced Neutron Capture Experiments (DANCE). This is the first direct measurement for many of these isotopes across the neutron energy spectrum of 10 eV to 1 MeV using the …
Relation Between Gravitational Mass And Baryonic Mass For Non-Rotating And Rapidly Rotating Neutron Stars,
2020
Beijing Normal University
Relation Between Gravitational Mass And Baryonic Mass For Non-Rotating And Rapidly Rotating Neutron Stars, He Gao, Shun-Ke Ai, Zhou-Jian Cao, Bing Zhang, Zhen-Yu Zhu, Ang Li, Nai-Bo Zhang, Andreas Bauswein
Physics & Astronomy Faculty Research
With a selected sample of neutron star (NS) equations of state (EOSs) that are consistent with the current observations and have a range of maximum masses, we investigate the relations between NS gravitational mass Mg and baryonic mass Mb, and the relations between the maximum NS mass supported through uniform rotation (Mmax) and that of nonrotating NSs (MTOV). We find that for an EOS-independent quadratic, universal transformation formula (Mb=Mg+A×M2g)(Mb=Mg+A×Mg2), the best-fit A value is 0.080 for non-rotating NSs, 0.064 for maximally rotating NSs, and 0.073 when NSs with arbitrary rotation are considered. The residual error of the transformation is ∼ …
A Spectropolarimetric Study Of Southern Wr + O Binaries,
2020
University of Denver
A Spectropolarimetric Study Of Southern Wr + O Binaries, Andrew G. Fullard
Electronic Theses and Dissertations
The classical Wolf-Rayet (WR) state is the evolved stage of a massive star, post main-sequence. They are characterized by their strong emission line spectra and stellar winds that are often more than 10 times denser than that of their progenitor O-type stars, which have mass loss rates of 10-6 MΘyr-1. The evolution of WR stars and their connection to specific types of supernovae (SNe) is an open question. Current theory suggests that rapidly rotating massive stars may be the progenitors of SNe that produce long-duration gamma-ray bursts. The interaction between WR stars and their companion …
Using Mesa To Test Our Theory Of Contact Binary Star Evolution,
2020
Calvin University
Using Mesa To Test Our Theory Of Contact Binary Star Evolution, Lauren Henderson, Anneke Avery, Gia Mien Le, Larry A. Molnar
Summer Research
A contact binary star system consists of two stars orbiting each other so closely that they share a common atmosphere (Figure 1). Nearly 1% of stars like our sun are contact binaries, yet there is not a comprehensive model of their lives. Our goal is to understand the formation, life, and explosive demise of these objects. This summer we used MESA, a stellar modeling program, paired with a Python program to model the lives of contact binary stars.
Exoplanets: Correlated Noise And Cautionary Tales,
2020
University of Central Florida
Exoplanets: Correlated Noise And Cautionary Tales, Ryan Challener
Electronic Theses and Dissertations, 2020-2023
Transiting exoplanets provide the best opportunity for planetary characterization, and thus the search for life outside the Solar System. These planets orbit such that they pass in front ("transit'') and behind ("eclipse'') their host star, and a spectrum of the lost flux constrains the atmospheric properties of the planet. In transits, the flux modulation scales with the cross-sectional area of the planet, and the spectrum includes signatures of molecules in the upper atmosphere of the planet's terminator, which the host star's light passes through on the way to the observer. With eclipses, the lost flux is the direct emission of …
Measured Optical Absorption Cross Sections Of Tio,
2020
Old Dominion University
Measured Optical Absorption Cross Sections Of Tio, Peter Bernath
Chemistry & Biochemistry Faculty Publications
A laboratory emission spectrum of TiO in the visible and near-infrared regions (476–1176 nm) has been calibrated and corrected. High-resolution experimental absorption cross sections for TiO with natural isotopic abundance are provided at a temperature of about 2300 K. These cross sections have been compared with those derived from the ExoMol line list. The experimental cross sections can be used directly as a template for cross correlation TiO detection in hot Jupiter exoplanets.
Modeling The Galactic Compact Binary Neutron Star Population And Studying The Double Pulsar System,
2020
West Virginia University
Modeling The Galactic Compact Binary Neutron Star Population And Studying The Double Pulsar System, Nihan Pol
Graduate Theses, Dissertations, and Problem Reports (ETD)
Binary neutron star (BNS) systems consisting of at least one neutron star provide an avenue for testing a broad range of physical phenomena ranging from tests of General Relativity to probing magnetospheric physics to understanding the behavior of matter in the densest environments in the Universe. Ultra-compact BNS systems with orbital periods less than few tens of minutes emit gravitational waves with frequencies ~mHz and are detectable by the planned space-based Laser Interferometer Space Antenna (LISA), while merging BNS systems produce a chirping gravitational wave signal that can be detected by the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO). Thus, BNS …
