Chandra Spectral Measurements Of The O Supergiant Ζ Puppis Indicate A Surprising Increase In The Wind Mass-Loss Rate Over 18 Yr, David H. Cohen, Jiaming Wang , '22, V. Petit, M. A. Leutenegger, L. Dakir, C. Mayhue , '23, A. David-Uraz
Physics & Astronomy Faculty Works
New long Chandra grating observations of the O supergiant ζ Pup show not only a brightening of the X-ray emission line flux of 13 per cent in the 18 yr since Chandra’s first observing cycle, but also clear evidence – at more than 4σ significance – of increased wind absorption signatures in its Doppler-broadened line profiles. We demonstrate this with non-parametric analysis of the profiles as well as Gaussian fitting and then use line-profile model fitting to derive a mass-loss rate of 2.47 ± 0.09 × 10−6[Math Processing Error], which is a 40 per cent increase over the value ...
Investigation On The Use Of Small Aperture Telescopes For Leo Satellite Orbit Determination, 2020 California Polytechnic State University, San Luis Obispo
Investigation On The Use Of Small Aperture Telescopes For Leo Satellite Orbit Determination, Luis R. Curiel Iii
The following thesis regards the use of small aperture telescopes for space domain awareness efforts. The rapidly populating space domain was motivation for the development of a new operation scheme to conduct space domain awareness feasibility studies using small telescopes. Two 14-inch Schmidt-Cassegrain Telescopes at the California Polytechnic State University and the Air Force Research Lab in Kirtland AFB, NM, in conjunction with a dedicated CCD camera and a commercial DSLR camera, were utilized to conduct optical observations on satellites in Earth orbit.
Satellites were imaged during August 2019, and from January 2020 to March 2020, resulting in the collection ...
Nearly 30,000 Late-Type Main-Sequence Stars With Stellar Age From Lamost Dr5, 2020 University of Chinese Academy of Sciences
Nearly 30,000 Late-Type Main-Sequence Stars With Stellar Age From Lamost Dr5, Jiajun Zhang, Terry D. Oswalt, Jingkun Zhao, Xilong Liang, Xianhao Ye, Gang Zhao
We construct a sample of nearly 30,000 main-sequence stars with 4500K < Teﬀ < 5000K and stellar ages estimated by the chromospheric activity−age relation. This sample is used to determine the age distribution in the R − Z plane of the Galaxy, where R is the projected Galactocentric distance in the disk midplane and Z is the height above the disk midplane. As |Z| increases, the percentage of old stars becomes larger. It is known that scale-height of Galactic disk increases as R increases, which is called ﬂare. A mild ﬂare from R ∼ 8.0 to 9.0 kpc in stellar age distribution is found. We also ﬁnd that the velocity dispersion increases with age as conﬁrmed by previous studies. Finally we present spiral-shaped structures in Z − υZ phase space in three stellar age bins. The spiral is clearly seen in the age bin of [0, 1] Gyr, which suggests that a vertical perturbation to the disk probably took place within the last ∼ 1.0 Gyr.
Tidal Locking And The Gravitational Fold Catastrophe, 2020 CUNY New York City College of Technology
Tidal Locking And The Gravitational Fold Catastrophe, Andrea Ferroglia, Miguel C. N. Fiolhais
Publications and Research
The purpose of this work is to study the phenomenon of tidal locking in a pedagogical framework by analyzing the effective gravitational potential of a two-body system with two spinning objects. It is shown that the effective potential of such a system is an example of a fold catastrophe. In fact, the existence of a local minimum and saddle point, corresponding to tidally locked circular orbits, is regulated by a single dimensionless control parameter that depends on the properties of the two bodies and on the total angular momentum of the system. The method described in this work results in ...
Measurements And Mitigation Of Scattered Light Noise In Ligo, 2020 Louisiana State University and Agricultural and Mechanical College
Measurements And Mitigation Of Scattered Light Noise In Ligo, Corey Daniel Austin
LSU Doctoral Dissertations
The Advanced LIGO (aLIGO) detectors use 1064 nm lasers to measure the tiny fluctuations in spacetime that occur when gravitational waves pass through the earth. LIGO makes use of advanced coating methods and materials to limit the amount of light that scatters from the main beam, but some amount of light does scatter. This stray light can interact with surfaces inside the interferometer that are not seismically isolated and then recombine with the main beam, introducing excess noise into the gravitational wave channel. This thesis reviews the methods for modeling scattered light with ray tracing software and analytical models, for ...
A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, 2020 University of Missouri-St. Louis
A Spectroscopic And Photometric Survey Of The W4 Hii Region And Its Young Stellar Population, Matt Wentzel-Long
The W4 HII region is home to a large number of O and B-type stars as well as the young open cluster IC 1805. OB-type produce intense photoionizing radiation and stellar winds that can induce star formation in surrounding molecular clouds and sometimes carve out large regions of decreased particle density called superbubbles. During the star formation process, young stellar objects (YSOs) are initially surrounded by circumstellar disks made of gas and dust which naturally dissipate after several million years. The dissipation of the disk is thought to occur for a variety of reasons, including photoevaporation by the encompassed protostar ...
Galaxy And Mass Assembly (Gama): A Wise Study Of The Activity Of Emission-Line Systems In G23, 2020 University of the Western Cape
Galaxy And Mass Assembly (Gama): A Wise Study Of The Activity Of Emission-Line Systems In G23, H. F.M. Yao, T. H. Jarrett, M. E. Cluver, L. Marchetti, Edward N. Taylor, M. G. Santos, Matt S. Owers, Angel R. Lopez-Sanchez, Y. A. Gordon, M. J.I. Brown, S. Brough, S. Phillipps, Benne Holwerda, A. M. Hopkins, L. Wang
We present a detailed study of emission-line systems in the Galaxy And Mass Assembly (GAMA) G23 region, making use of Wide-field Infrared Survey Explorer (WISE) photometry that includes carefully measured resolved sources. After applying several cuts to the initial catalog of. 41,000 galaxies, we extract a sample of 9809 galaxies. We then compare the spectral diagnostic Baldwin, Philips & Terlevich (BPT) classification of 1154 emission-line galaxies (38% resolved in W1) to their location in the WISE color-color diagram, leading to the creation of a new zone for mid-infrared "warm"galaxies located 2μm above the star-forming sequence, below the standard WISE ...
The Evolution Of A Circumplanetary Disc With A Dead Zone, 2020 University of Nevada, Las Vegas
The Evolution Of A Circumplanetary Disc With A Dead Zone, Cheng Chen, Chao Chin Yang, Rebecca G. Martin, Zhaohuan Zhu
Physics & Astronomy Faculty Publications
© 2021 Oxford University Press. All rights reserved. We investigate whether the regular Galilean satellites could have formed in the dead zone of a circumplanetary disc. A dead zone is a region of weak turbulence in which the magnetorotational instability is suppressed, potentially an ideal environment for satellite formation. With the grid-based hydrodynamic code FARGO3D, we examine the evolution of a circumplanetary disc model with a dead zone. Material accumulates in the dead zone of the disc leading to a higher total mass and but a similar temperature profile compared to a fully turbulent disc model. The tidal torque increases the ...
Improving The Robustness Of The Advanced Ligo Detectors To Earthquakes, 2020 The University of Texas Rio Grande Valley
Improving The Robustness Of The Advanced Ligo Detectors To Earthquakes, Eyal Schwartz, A. Pele, J. Warner, B. Lantz, Joseph Betzwieser, K. L. Dooley, S. Biscans, K. E. Ramirez
Physics and Astronomy Faculty Publications and Presentations
Teleseismic, or distant, earthquakes regularly disrupt the operation of ground–based gravitational wave detectors such as Advanced LIGO. Here, we present EQ mode, a new global control scheme, consisting of an automated sequence of optimized control filters that reduces and coordinates the motion of the seismic isolation platforms during earthquakes. This, in turn, suppresses the differential motion of the interferometer arms with respect to one another, resulting in a reduction of DARM signal at frequencies below 100 mHz. Our method greatly improved the interferometers' capability to remain operational during earthquakes, with ground velocities up to 3.9 μm s ...
Gwtc-2: Compact Binary Coalescences Observed By Ligo And Virgo During The First Half Of The Third Observing Run, 2020 Missouri University of Science and Technology
Gwtc-2: Compact Binary Coalescences Observed By Ligo And Virgo During The First Half Of The Third Observing Run, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, Download The Pdf.
Physics Faculty Research & Creative Works
We report on gravitational wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo between 1 April 2019 15:00 UTC and 1 October 2019 15:00 UTC. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near real-time through GCN Notices and Circulars; 13 are reported here for the first time. The catalog contains events whose sources ...
Galaxy And Mass Assembly: A Comparison Between Galaxy⇓Galaxy Lens Searches In Kids/Gama, 2020 University of Louisville
Galaxy And Mass Assembly: A Comparison Between Galaxy⇓Galaxy Lens Searches In Kids/Gama, Shawn Knabel, Rebecca L. Steele, Benne W. Holwerda, Joanna S. Bridge, Alice Jacques, Andrew M. Hopkins, Stephen P. Bamford, Michael J.I. Brown, Sarah Brough, Lee Kelvin, Maciej Bilicki, John Kielkopf
Strong gravitational lenses are a rare and instructive type of astronomical object. Identification has long relied on serendipity, but different strategies—such as mixed spectroscopy of multiple galaxies along the line of sight, machine-learning algorithms, and citizen science—have been employed to identify these objects as new imaging surveys become available. We report on the comparison between spectroscopic, machine-learning, and citizen-science identification of galaxy–galaxy lens candidates from independently constructed lens catalogs in the common survey area of the equatorial fields of the Galaxy and Mass Assembly survey. In these, we have the opportunity to compare high completeness spectroscopic identifications ...
Galaxy And Mass Assembly: Luminosity And Stellar Mass Functions In Gama Groups, 2020 University of Sussex
Galaxy And Mass Assembly: Luminosity And Stellar Mass Functions In Gama Groups, J. A. Vazquez-Mata, J. Loveday, S. D. Riggs, I. K. Baldry, L. J.M. Davies, A. S.G. Robotham, Benne W. Holwerda, M. J.I. Brown, M. E. Cluver, L. Wang, M. Alpaslan, J. Bland-Hawthorn, S. Brough, S. P. Driver, A. M. Hopkins, E. N. Taylor, A. H. Wright
How do galaxy properties (such as stellar mass, luminosity, star formation rate, and morphology) and their evolution depend on the mass of their host dark matter halo? Using the Galaxy and Mass Assembly group catalogue, we address this question by exploring the dependence on host halo mass of the luminosity function (LF) and stellar mass function (SMF) for grouped galaxies subdivided by colour, morphology, and central/satellite. We find that spheroidal galaxies in particular dominate the bright and massive ends of the LF and SMF, respectively. More massive haloes host more massive and more luminous central galaxies. The satellites LF ...
Telescope Parallel Actuator Mount: Control And Testing, 2020 California Polytechnic State University, San Luis Obispo
Telescope Parallel Actuator Mount: Control And Testing, Samuel S. Artho-Bentz
This thesis approaches the task of designing a control system for the Parallel Actuator Mount developed by Dr. John Ridgely and Mr. Garrett Gudgel. It aims to create a base framework that directly controls the telescope and can be expanded to accept external command. It incorporates lower priced components and develops more easily approachable software with great functionality. An open-loop method for velocity control is established. Developing repeatable tests is a major focus. Testing finds the control methods developed result in velocity error of less than 5% and position error of less than 1.5% despite several mechanical issues and ...
Mid-Infrared Studies Of Galactic Sources: Probing The Relationship Between Polycyclic Aromatic Hydrocarbons And Their Physical Environment, 2020 The University of Western Ontario
Mid-Infrared Studies Of Galactic Sources: Probing The Relationship Between Polycyclic Aromatic Hydrocarbons And Their Physical Environment, Collin Matthew Knight
Electronic Thesis and Dissertation Repository
Over the past 50 years, prominent mid-infrared (MIR) emission features from 3--20 $\mu$m have been observed ubiquitously in the interstellar medium (ISM) of Galactic and extragalactic sources. These emission features arise from the vibrational relaxation of polycyclic aromatic hydrocarbons (PAHs) after the absorption of a far-ultraviolet (FUV) photon. PAHs are astronomically significant in that they contain up to 15\% of the cosmic carbon inventory and play an important role in the physical and chemical processes of the ISM such as, for example, the gas heating and the ionization balance. Variations in the relative strengths of the major PAH bands ...
Demonstration Of Dynamic Thermal Compensation For Parametric Instability Suppression In Advanced Ligo, 2020 Louisiana State Univ, Baton Rouge, LA 70803 USA
Demonstration Of Dynamic Thermal Compensation For Parametric Instability Suppression In Advanced Ligo, T. Hardwick, V. J. Hamedan, C. Blair, A. C. Green, D. Vander-Hyde
Advanced LIGO and other ground-based interferometric gravitational-wave detectors use high laser power to minimize shot noise and suspended optics to reduce seismic noise coupling. This can result in an opto-mechanical coupling which can become unstable and saturate the interferometer control systems. The severity of these parametric instabilities scales with circulating laser power and first hindered LIGO operations in 2014. Static thermal tuning and active electrostatic damping have previously been used to control parametric instabilities at lower powers but are insufficient as power is increased. Here we report the first demonstration of dynamic thermal compensation to avoid parametric instability in an ...
Structural Evolution And Magnetic Properties Of Gd2hf2o7 Nanocrystals: Computational And Experimental Investigations, 2020 The University of Texas Rio Grande Valley
Structural Evolution And Magnetic Properties Of Gd2hf2o7 Nanocrystals: Computational And Experimental Investigations, Madhab Pokhrel, N. Dimakis, Gamage Chamath Dannangoda, Santosh K. Gupta, Karen S. Martirosyan, Yuanbing Mao
Physics and Astronomy Faculty Publications and Presentations
Structural evolution in functional materials is a physicochemical phenomenon, which is important from a fundamental study point of view and for its applications in magnetism, catalysis, and nuclear waste immobilization. In this study, we used x-ray diffraction and Raman spectroscopy to examine the Gd2Hf2O7 (GHO) pyrochlore, and we showed that it underwent a thermally induced crystalline phase evolution. Superconducting quantum interference device measurements were carried out on both the weakly ordered pyrochlore and the fully ordered phases. These measurements suggest a weak magnetism for both pyrochlore phases. Spin density calculations showed that the Gd3 ...
Gravitational-Wave Constraints On The Equatorial Ellipticity Of Millisecond Pulsars, 2020 California Institute of Technology
Gravitational-Wave Constraints On The Equatorial Ellipticity Of Millisecond Pulsars, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Ansoldi, J. M. Antelis, S. Antier, S. Appert, K. Arai, Tiffany Z. Summerscales
© 2020. The American Astronomical Society. All rights reserved.. We present a search for continuous gravitational waves from five radio pulsars, comprising three recycled pulsars (PSR J0437-4715, PSR J0711-6830, and PSR J0737-3039A) and two young pulsars: the Crab pulsar (J0534+2200) and the Vela pulsar (J0835-4510). We use data from the third observing run of Advanced LIGO and Virgo combined with data from their first and second observing runs. For the first time, we are able to match (for PSR J0437-4715) or surpass (for PSR J0711-6830) the indirect limits on gravitational-wave emission from recycled pulsars inferred from their observed spin-downs, and ...
Detection Of Reconnection Signatures In Solar Flares, 2020 National Center for Atmospheric Research
Detection Of Reconnection Signatures In Solar Flares, Taylor R. Whitney Aegerter, Daniel J. Emmons Ii, Robert D. Loper
Solar flare forecasting is limited by the current understanding of mechanisms that govern magnetic reconnection, the main physical phenomenon associated with these events. As a result, forecasting relies mainly on climatological correlations to historical events rather than the underlying physics principles. Solar physics models place the neutral point of the reconnection event in the solar corona. Correspondingly, studies of photospheric magnetic fields indicate changes during solar flares—particularly in relation to the field helicity—on the solar surface as a result of the associated magnetic reconnection. This study utilizes data from the Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager ...
Using Saoimage Ds9 & Hubble Space Telescope Data To Identify Globular Clusters In Ic 219, 2020 University of Louisville
Using Saoimage Ds9 & Hubble Space Telescope Data To Identify Globular Clusters In Ic 219, Emily Spicer, Alice Jacques, Benne Holwerda
Undergraduate Research Events
Globular clusters are tightly bound spherical clusters of stars located within the halo of elliptical and spiral galaxies. They are among the oldest stars found in a galaxy, and their presence and abundance in a galaxy’s halo offer insight on the age, composition, and formation of the galaxy.1 I used a Hubble Space Telescope (HST) image and SAOImage DS9, a powerful imaging tool used to analyze astronomical data, to identify the size and locate the position of globular cluster (GC) candidates in IC 219.
Physics For Everyone, 2020 CUNY College of Staten Island
Physics For Everyone, Charles Liu, Sarang Gopalakrishnan, Vadim Oganesyan
Open Educational Resources
The online educational resource Physics For Everyone is the scaffolding for a 3 contact hour, 3 credit general education course that will be offered for the first time at the CUNY College of Staten Island in the spring semester of 2021. This work has been generously supported by New America’s PIT-UN (Public Interest Technology University Network) challenge grant program, and is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.
This slide deck provides the outline for the semester-long course. Each week’s lecture topics, with key points to be covered, are highlighted in two slides, which also ...