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2019

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Articles 151 - 180 of 381

Full-Text Articles in Astrophysics and Astronomy

Task-Layer Multiplicity As A Measure Of Community Level Health, Phil Fraundorf Jul 2019

Task-Layer Multiplicity As A Measure Of Community Level Health, Phil Fraundorf

Physics Faculty Works

Te insights of many disciplines, and of commonsense, about individual-level well-being might be strengthened by a shif in focus to community-level well-being in a way that respects belief systems as well as the power of each individual. We start with the jargon of complex systems and the possibility that a small number of broken symmetries, marked by the edges of a hierarchical series of physical subsystem types, underlie the delicate correlation-based complexity of life on our planet’s surface. We show that an information-theory-inspired model of attention-focus on correlation layers, which looks in/out from the boundaries of skin, family, and culture, …

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“Where Is Everybody?” Fermi’S Paradox, Evolution, And Sin, Noreen L. Herzfeld Jul 2019

“Where Is Everybody?” Fermi’S Paradox, Evolution, And Sin, Noreen L. Herzfeld

Computer Science Faculty Publications

The Search for Extraterrestrial Intelligence (SETI) project has been scanning the heavens for signs of intelligent life for almost half a century. So far, nothing. This raises the question physicist Enrico Fermi asked, "Where is everybody?" The probability of intelligent life on another planet is high so why the silence? Technological civilizations may be short-lived. The mechanisms of evolution that lead to intelligent life and technological development also lead to propensities traditionally labeled as sin. These propensities make it difficult for technological civilizations to survive long enough to escape their home planet.

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Magnetic Ob[A] Stars With Tess: Probing Their Evolutionary And Rotational Properties (Mobster) – I. First-Light Observations Of Known Magnetic B And A Stars, A. David-Uraz, C. Neiner, J. Sikora, D. M. Bowman, V. Petit, S. Chowdhury, G. Handler, M. Pergeorelis, M. Cantiello, David H. Cohen, C. Erba, Z. Keszthelyi, V. Khalack, O. Kobzar, O. Kochukhov, J. Labadie-Bartz, C. C. Lovekin, R. Macinnis, S. P. Owocki, H. Pablo, M. E. Shultz, A. Ud-Doula, G. A. Wade, Mobster Collaboration Jul 2019

Magnetic Ob[A] Stars With Tess: Probing Their Evolutionary And Rotational Properties (Mobster) – I. First-Light Observations Of Known Magnetic B And A Stars, A. David-Uraz, C. Neiner, J. Sikora, D. M. Bowman, V. Petit, S. Chowdhury, G. Handler, M. Pergeorelis, M. Cantiello, David H. Cohen, C. Erba, Z. Keszthelyi, V. Khalack, O. Kobzar, O. Kochukhov, J. Labadie-Bartz, C. C. Lovekin, R. Macinnis, S. P. Owocki, H. Pablo, M. E. Shultz, A. Ud-Doula, G. A. Wade, Mobster Collaboration

Physics & Astronomy Faculty Works

In this paper we introduce the MOBSTER collaboration and lay out its scientific goals. We present first results based on the analysis of 19 previously known magnetic O, B, and A stars observed in 2-min cadence in sectors 1 and 2 of the Transiting Exoplanet Survey Satellite (TESS) mission. We derive precise rotational periods from the newly obtained light curves and compare them to previously published values. We also discuss the overall photometric phenomenology of the known magnetic massive and intermediate-mass stars and propose an observational strategy to augment this population by taking advantage of the high-quality observations produced by …

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The L 98-59 System: Three Transiting, Terrestrial-Size Planets Orbiting A Nearby M Dwarf, V. B. Kostov, J. E. Schlieder, T. Barclay, E. V. Quintana, K. D. Colón, J. Brande, K. A. Collins, A. D. Feinstein, S. Hadden, S. R. Kane, L. Kreidberg, E. Kruse, C. Lam, E. Matthews, B. T. Montet, F. J. Pozuelos, K. G. Stassun, J. G. Winters, G. Ricker, R. Vanderspek, D. Latham, S. Seager, J. Winn, J. M. Jenkins, D. Afanasev, J. J. D. Armstrong, G. Arney, P. Boyd, G. Barentsen, K. Barkaoui, N. E. Batalha, C. Beichman, D. Bayliss, C. Burke, A. Burdanov, L. Cacciapuoti, A. Carson, D. Charbonneau, J. Christiansen, D. Ciardi, M. Clampin, K. I. Collins, D. M. Conti, J. Coughlin, G. Covone, I. Crossfield, L. Delrez, S. Domagal-Goldman, C. Dressing, E. Ducrot, Z. Essack, M. E. Everett, T. Fauchez, D. Foreman-Mackey, T. Gan, E. Gilbert, M. Gillon, E. Gonzales, A. Hamann, C. Hedges, H. Hocutt, K. Hoffman, E. P. Horch, K. Home, S. Howell, S. Hynes, M. Ireland, J. M. Irwin, G. Isopi, Eric L.N. Jensen, E. Jehin, L. Kaltenegger, J. F. Kielkopf, R. Kopparapu, N. Lewis, E. Lopez, J. J. Lissauer, A. W. Mann, F. Mallia, A. Mandell, R. A. Matson, T. Mazeh, T. Monsue, S. E. Moran, V. Moran, C. V. Morley, B. Morris, P. Muirhead, K. Mukai, S. Mullally, F. Mullally, C. Murray, N. Narita, E. Palle, D. Pidhorodetska, D. Quinn, H. Relles, S. Rinehart, M. Ritsko, J. E. Rodriguez, P. Rowden, J. F. Row, D. Sebastian, R. Sefako, S. Shahaf, A. Shporer, N. Tañón Reyes, P. Tenenbaum, E. B. Ting, J. D. Twicken, G. T. Van Belle, L. Vega, J. Volosin Jul 2019

The L 98-59 System: Three Transiting, Terrestrial-Size Planets Orbiting A Nearby M Dwarf, V. B. Kostov, J. E. Schlieder, T. Barclay, E. V. Quintana, K. D. Colón, J. Brande, K. A. Collins, A. D. Feinstein, S. Hadden, S. R. Kane, L. Kreidberg, E. Kruse, C. Lam, E. Matthews, B. T. Montet, F. J. Pozuelos, K. G. Stassun, J. G. Winters, G. Ricker, R. Vanderspek, D. Latham, S. Seager, J. Winn, J. M. Jenkins, D. Afanasev, J. J. D. Armstrong, G. Arney, P. Boyd, G. Barentsen, K. Barkaoui, N. E. Batalha, C. Beichman, D. Bayliss, C. Burke, A. Burdanov, L. Cacciapuoti, A. Carson, D. Charbonneau, J. Christiansen, D. Ciardi, M. Clampin, K. I. Collins, D. M. Conti, J. Coughlin, G. Covone, I. Crossfield, L. Delrez, S. Domagal-Goldman, C. Dressing, E. Ducrot, Z. Essack, M. E. Everett, T. Fauchez, D. Foreman-Mackey, T. Gan, E. Gilbert, M. Gillon, E. Gonzales, A. Hamann, C. Hedges, H. Hocutt, K. Hoffman, E. P. Horch, K. Home, S. Howell, S. Hynes, M. Ireland, J. M. Irwin, G. Isopi, Eric L.N. Jensen, E. Jehin, L. Kaltenegger, J. F. Kielkopf, R. Kopparapu, N. Lewis, E. Lopez, J. J. Lissauer, A. W. Mann, F. Mallia, A. Mandell, R. A. Matson, T. Mazeh, T. Monsue, S. E. Moran, V. Moran, C. V. Morley, B. Morris, P. Muirhead, K. Mukai, S. Mullally, F. Mullally, C. Murray, N. Narita, E. Palle, D. Pidhorodetska, D. Quinn, H. Relles, S. Rinehart, M. Ritsko, J. E. Rodriguez, P. Rowden, J. F. Row, D. Sebastian, R. Sefako, S. Shahaf, A. Shporer, N. Tañón Reyes, P. Tenenbaum, E. B. Ting, J. D. Twicken, G. T. Van Belle, L. Vega, J. Volosin

Physics & Astronomy Faculty Works

We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-size planets transiting L 98-59 (TOI-175, TIC 307210830)—a bright M dwarf at a distance of 10.6 pc. Using the Gaia-measured distance and broadband photometry, we find that the host star is an M3 dwarf. Combined with the TESS transits from three sectors, the corresponding stellar parameters yield planet radii ranging from 0.8 R⊕ to 1.6 R⊕. All three planets have short orbital periods, ranging from 2.25 to 7.45 days with the outer pair just wide of a 2:1 period resonance. Diagnostic tests produced by the TESS …

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Embedding Climate Change Engagement In Astronomy Education And Research, Kathryn Williamson, Travis A. Rector, James D. Lowenthal Jul 2019

Embedding Climate Change Engagement In Astronomy Education And Research, Kathryn Williamson, Travis A. Rector, James D. Lowenthal

Astronomy: Faculty Publications

This White Paper is a call to action for astronomers to respond to climate change with a large structural transition within our profession. Many astronomers are deeply concerned about climate change and act upon it in their personal and professional lives, and many organizations within astronomy have incorporated incremental changes. We need a collective impact model to better network and grow our efforts so that we can achieve results that are on the scale appropriate to address climate change at the necessary level indicated by scientific research; e.g., becoming carbon neutral by 2050. We need to implement strategies within two …

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Brightest Cluster Galaxy Evolution Exploration: Comparing The Separation Of Cluster X-Ray Light And Visible Wavelength Galaxy Light With Spectral Data, Matthew Aaron Salinas Jul 2019

Brightest Cluster Galaxy Evolution Exploration: Comparing The Separation Of Cluster X-Ray Light And Visible Wavelength Galaxy Light With Spectral Data, Matthew Aaron Salinas

Physics

Brightest Cluster Galaxies (BCGs), the brightest galaxy in a cluster of hundreds to thousands of galaxies, are some of the biggest, brightest, and most massive galaxies in the universe. Characterizing a BCG can help discover more about galaxy evolution - the aging, changing, and possible merging (collisions) of galaxies. This project involves determining the separation of the peak of x-ray emission of the galaxy cluster, and the peak of visible emission of the BCG to characterize the system as being disturbed or undisturbed that can then lead to discoveries about its formation and evolution. We have found that 17.4% of …

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Tests Of General Relativity With Gw170817, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration Jul 2019

Tests Of General Relativity With Gw170817, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due …

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An Emission Spectrum For Wasp-121b Measured Across The 0.8–1.1 Μm Wavelength Range Using The Hubble Space Telescope, Thomas Mikal-Evans, David K. Sing, Jayesh M. Goyal, Benjamin Drummond, Aarynn L. Carter, Gregory W. Henry, Hannah R. Wakeford, Nikole K. Lewis, Mark S. Marley, Pascal Tremblin, Nikolay Nikolov, Tiffany Kataria, Drake Deming, Gilda E. Ballester Jun 2019

An Emission Spectrum For Wasp-121b Measured Across The 0.8–1.1 Μm Wavelength Range Using The Hubble Space Telescope, Thomas Mikal-Evans, David K. Sing, Jayesh M. Goyal, Benjamin Drummond, Aarynn L. Carter, Gregory W. Henry, Hannah R. Wakeford, Nikole K. Lewis, Mark S. Marley, Pascal Tremblin, Nikolay Nikolov, Tiffany Kataria, Drake Deming, Gilda E. Ballester

Information Systems and Engineering Management Research Publications

WASP-121b is a transiting gas giant exoplanet orbiting close to its Roche limit, with an inflated radius nearly double that of Jupiter and a dayside temperature comparable to a late M dwarf photosphere. Secondary eclipse observations covering the 1.1–1.6μm wavelength range have revealed an atmospheric thermal inversion on the dayside hemisphere, likely caused by high-altitude absorption at optical wavelengths. Here we present secondary eclipse observations made with the Hubble Space Telescope Wide Field Camera 3 spectrograph that extend the wavelength coverage from 1.1μm down to 0.8μm⁠. To determine the atmospheric properties from the measured eclipse spectrum, we performed a retrieval …

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Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration Jun 2019

Narrow-Band Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while coherently integrating the entire dataset. In …

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Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015–2017 Ligo Data, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone Jun 2019

Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015–2017 Ligo Data, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Robert Stone

Physics & Astronomy Faculty Publications

We present a search for gravitational waves from 222 pulsars with rotation frequencies ≳10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015–2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = …

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Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015–2017 Ligo Data, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration Jun 2019

Searches For Gravitational Waves From Known Pulsars At Two Harmonics In 2015–2017 Ligo Data, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration

Faculty Publications

We present a search for gravitational waves from 222 pulsars with rotation frequencies 10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015–2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar's rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = …

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On The Balance Between Plasma And Magnetic Pressure Across Equatorial Plasma Depletions, J. Rodríguez-Zuluaga, C. Stolle, Y. Yamazaki, H. Lühr, J. Park, Ludger Scherliess, J. L. Chau Jun 2019

On The Balance Between Plasma And Magnetic Pressure Across Equatorial Plasma Depletions, J. Rodríguez-Zuluaga, C. Stolle, Y. Yamazaki, H. Lühr, J. Park, Ludger Scherliess, J. L. Chau

All Physics Faculty Publications

In magnetized plasmas such as the ionosphere, electric currents develop in regions of strong density gradients to balance the resulting plasma pressure gradients. These currents, usually known as diamagnetic currents decrease the magnetic pressure where the plasma pressure increases, and vice versa. In the low‐latitude ionosphere, equatorial plasma depletions (EPDs) are well known for their steep plasma density gradients and adverse effect on radio wave propagation. In this paper, we use continuous measurements of the magnetic field and electron density from the European Space Agency's Swarm constellation mission to assess the balance between plasma and magnetic pressure across large‐scale EPDs. …

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Rotational Quenching Of Hd Induced By Collisions With H2 Molecules, Yier Wan, Nadulvalath Balakrishnan, B. H. Yang, R. C. Forrey, P. C. Stancil Jun 2019

Rotational Quenching Of Hd Induced By Collisions With H2 Molecules, Yier Wan, Nadulvalath Balakrishnan, B. H. Yang, R. C. Forrey, P. C. Stancil

Chemistry and Biochemistry Faculty Research

Rate coefficients for rotational transitions in HD induced by H2 impact for rotational levels of HD j ≤ 8 and temperatures 10 K ≤ T ≤ 5000 K are reported. The quantum mechanical close-coupling (CC) method and the coupled-states (CS) decoupling approximation are used to obtain the cross-sections employing the most recent highly accurate H2–H2 potential energy surface (PES). Our results are in good agreement with previous calculations for low-lying rotational transitions The cooling efficiency of HD compared with H2 and astrophysical applications are briefly discussed.

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Methanol Masers In Star-Forming Regions, Nicolas Clarisse, Anuj P. Sarma Jun 2019

Methanol Masers In Star-Forming Regions, Nicolas Clarisse, Anuj P. Sarma

DePaul Discoveries

Methanol molecules in star-forming regions emit detectable microwave radiation. In particular, the rotational energy state transitions of methanol are responsible for two types of masers: Class I and Class II, found in the bipolar outflows and accretion disks of star-forming regions, respectively. Masers, being intense point-like sources in our sky, serve as an excellent source of information in further understanding the environment of high-mass star-forming regions due to their intense luminosities. High-mass star formation is still not entirely understood and remains an observational challenge. We have compiled a list of all the methanol maser transitions observed in the literature, in …

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Hierarchical Structure Formation In The Sdss Eboss Ly-Alpha Forests, Devin Becker Jun 2019

Hierarchical Structure Formation In The Sdss Eboss Ly-Alpha Forests, Devin Becker

DePaul Discoveries

In this study, we examine hierarchical structure at large redshifts utilizing Sloan Digital Sky Survey (SDSS) Lyman-alpha forest data. Lyman-alpha forests are absorption lines in the spectrum of quasars that serve as tracers for clouds of primordial hydrogen. These data serve as a 1-dimensional probe of the matter density field at high redshift. Using a measure sensitive to hierarchical structure formation assembled around a discrete wavelet transform, we were able to detect hierarchical structure formation in the spectrum of every quasar studied. The nature of the hierarchy seems to pertain to two forms: one that is constant across all scales, …

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Spatially Resolved Stellar Populations And Kinematics With Kcwi: Probing The Assembly History Of The Massive Early-Type Galaxy Ngc 1407, Anna Ferré-Mateu, Duncan Forbes, Richard Mcdermid, Aaron Romanowsky, Jean Brodie Jun 2019

Spatially Resolved Stellar Populations And Kinematics With Kcwi: Probing The Assembly History Of The Massive Early-Type Galaxy Ngc 1407, Anna Ferré-Mateu, Duncan Forbes, Richard Mcdermid, Aaron Romanowsky, Jean Brodie

Faculty Publications

Using the newly commissioned Keck Cosmic Web Imager (KCWI) instrument on the Keck II telescope, we analyze the stellar kinematics and stellar populations of the well-studied massive early-type galaxy (ETG) NGC 1407. We obtained high signal-to-noise integral field spectra for a central and an outer (around one effective radius toward the southeast direction) pointing with integration times of just 600 s and 2400 s, respectively. We confirm the presence of a kinematically distinct core also revealed by VLT/MUSE data of the central regions. While NGC 1407 was previously found to have stellar populations characteristic of massive ETGs (with radially constant …

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How Bright Are Fast Optical Bursts Associated With Fast Radio Bursts?, Yuan-Pei Yang, Bing Zhang, Jian-Yan Wei Jun 2019

How Bright Are Fast Optical Bursts Associated With Fast Radio Bursts?, Yuan-Pei Yang, Bing Zhang, Jian-Yan Wei

Physics & Astronomy Faculty Research

The origin of fast radio bursts (FRBs) is still unknown. Multiwavelength observations during or shortly after the FRB phase would be essential to identify the counterpart of an FRB and to constrain its progenitor and environment. In this work, we investigate the brightness of the “fast optical bursts” (FOBs) associated with FRBs and the prospects of detecting them. We investigate several inverse Compton (IC) scattering processes that might produce an FOB, including both the one-zone and two-zone models. We also investigate the extension of the same mechanism of FRB emission to the optical band. We find that a detectable FOB …

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The Effect Of Binarity On Circumstellar Disk Evolution, S. A. Barenfeld, J. M. Carpenter, A. I. Sargent, A. C. Rizzuto, A. L. Kraus, T. Meshkat, R. L. Akeson, Eric L.N. Jensen, S. Hinkley Jun 2019

The Effect Of Binarity On Circumstellar Disk Evolution, S. A. Barenfeld, J. M. Carpenter, A. I. Sargent, A. C. Rizzuto, A. L. Kraus, T. Meshkat, R. L. Akeson, Eric L.N. Jensen, S. Hinkley

Physics & Astronomy Faculty Works

We present new results on how the presence of stellar companions affects disk evolution based on a study of the 5–11 Myr old Upper Scorpius OB Association. Of the 50 G0-M3 Upper Sco members with disks in our sample, only seven host a stellar companion within 2'' and brighter than K = 15, compared to 35 of 75 members without disks. This matches a trend seen in the 1–2 Myr old Taurus region, where systems with a stellar companion within 40 au have a lower fraction of infrared-identified disks than those without such companions, indicating shorter disk lifetimes in close …

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Thermodynamics Of Neutrons In A Magnetic Field And Its Implications For Neutron Stars, Efrain J. Ferrer, Aric Hackebill Jun 2019

Thermodynamics Of Neutrons In A Magnetic Field And Its Implications For Neutron Stars, Efrain J. Ferrer, Aric Hackebill

Physics & Astronomy Faculty Publications

We investigate the effects of a magnetic field on the thermodynamics of a neutron system at finite density and temperature. Our main motivation is to deepen the understanding of the physics of a class of neutron stars known as magnetars, which exhibit extremely strong magnetic fields. Taking into account two facts, (i) the existence of a pressure anisotropy in the presence of a magnetic field and (ii) that the quantum field theory contribution to the pressure is non-negligible, we show that the maximum value that the inner magnetic field of a star can reach while being in agreement with the …

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Propagation Of A Short Grb Jet In The Ejecta: Jet Launching Delay Time, Jet Structure, And Gw170817/Grb 170817a, Jin-Jun Geng, Bing Zhang, Anders Kölligan, Rolf Kuiper, Yong-Feng Huang Jun 2019

Propagation Of A Short Grb Jet In The Ejecta: Jet Launching Delay Time, Jet Structure, And Gw170817/Grb 170817a, Jin-Jun Geng, Bing Zhang, Anders Kölligan, Rolf Kuiper, Yong-Feng Huang

Physics & Astronomy Faculty Research

We perform a series of relativistic magnetohydrodynamic simulations to investigate how a hot magnetic jet propagates within the dynamical ejecta of a binary neutron star merger, focusing on how the jet structure depends on the delay time of jet launching with respect to the merger time, Δt jet. We find that regardless of the jet-launching delay time, a structured jet with an angle-dependent luminosity and Lorentz factor is always formed after the jet breaks out of the ejecta. On the other hand, the jet-launching delay time has an impact on the jet structure. If the jet-launching delay time is relatively …

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Variability In The Atmosphere Of The Hot Jupiter Kepler-76b, Brian Jackson, Elisabeth Adams, Wesley Sandidge, Steven Kreyche, Jennifer Briggs Jun 2019

Variability In The Atmosphere Of The Hot Jupiter Kepler-76b, Brian Jackson, Elisabeth Adams, Wesley Sandidge, Steven Kreyche, Jennifer Briggs

Physics Faculty Publications and Presentations

No abstract provided.

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The Newborn Planet Population Emerging From Ring-Like Structures In Discs, Giuseppe Lodato, Giovanni Dipierro, Enrico Ragusa, Feng Long, Gregory J. Herczeg, Ilaria Pascucci, Paola Pinilla, Carlo F. Manara, Marco Tazzari, Yao Liu, Gijs D. Mulders, Daniel Harsono, Yann Boehler, François Ménard, Doug Johnstone, Colette Salyk, Gerrit Van Der Plas, Sylvie Cabrit, Suzan Edwards, William J. Fischer, Nathan Hendler, Brunella Nisini, Elisabetta Rigliaco, Henning Avenhaus, Andrea Banzatti, Michael Gully-Santiago Jun 2019

The Newborn Planet Population Emerging From Ring-Like Structures In Discs, Giuseppe Lodato, Giovanni Dipierro, Enrico Ragusa, Feng Long, Gregory J. Herczeg, Ilaria Pascucci, Paola Pinilla, Carlo F. Manara, Marco Tazzari, Yao Liu, Gijs D. Mulders, Daniel Harsono, Yann Boehler, François Ménard, Doug Johnstone, Colette Salyk, Gerrit Van Der Plas, Sylvie Cabrit, Suzan Edwards, William J. Fischer, Nathan Hendler, Brunella Nisini, Elisabetta Rigliaco, Henning Avenhaus, Andrea Banzatti, Michael Gully-Santiago

Astronomy: Faculty Publications

ALMA has observed a plethora of ring-like structures in planet-forming discs at distances of 10–100 au from their host star. Although several mechanisms have been invoked to explain the origin of such rings, a common explanation is that they trace new-born planets. Under the planetary hypothesis, a natural question is how to reconcile the apparently high frequency of gap-carving planets at 10–100 au with the paucity of Jupiter-mass planets observed around main-sequence stars at those separations. Here, we provide an analysis of the new-born planet population emerging from observations of gaps in discs, under the assumption that the observed gaps …

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Differential Photometry Of Active Galactic Nuclei Using Time Resolved Observations With The 1m Nickel Telescope Of Lick Observatory, Chance L. Spencer Jun 2019

Differential Photometry Of Active Galactic Nuclei Using Time Resolved Observations With The 1m Nickel Telescope Of Lick Observatory, Chance L. Spencer

Physics

Active galactic nuclei (AGNs) are exotic objects in the center of some galaxies with luminosities that can greatly outshine the stars of the host galaxy across the entire electromagnetic spectrum. The origin of the UV/optical light is thought to be due to accretion of material onto the supermassive black hole in their centers. Since these objects are too far away to resolve the gravitational sphere of influence of the black hole directly, we make use of a method called reverberation mapping. We measure the lag between the AGN power-law continuum emitted by the accretion disk and the Doppler-broadened emission lines …

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Microcontroller Differential Gps To Subtract Signal Delay Due To Ambient Free Electrons In The Ionosphere, Diana Jane Swanson Jun 2019

Microcontroller Differential Gps To Subtract Signal Delay Due To Ambient Free Electrons In The Ionosphere, Diana Jane Swanson

Physics

The goal of this project is to create a Global Positioning System (GPS) receiver that is more precise than one GPS receiver on its own. The technique is to take the difference between a GPS receiver’s measured position and its actual position, then use radio frequency (RF) communication to send that differential value to another microcontroller GPS receiver. This differential value will be added to the measured second location to get a more accurate position for the second GPS receiver, thus creating a differential GPS.

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Multi-Wavelength Investigation Of Energy Release And Chromospheric Evaporation In Solar Flares, Viacheslav M. Sadykov May 2019

Multi-Wavelength Investigation Of Energy Release And Chromospheric Evaporation In Solar Flares, Viacheslav M. Sadykov

Dissertations

For a comprehensive understanding of the energy release and chromospheric evaporation processes in solar flares it is necessary to perform a combined multi-wavelength analysis using observations from space-based and ground-based observatories, and compare the results with predictions of the radiative hydrodynamic (RHD) flare models. Initially, the case study of spatially-resolved chromospheric evaporation properties for an M 1.0-class solar flare (SOL2014-06-12T21:12) using data form IRIS (Interface Region Imaging Spectrograph), HMI/SDO (Helioseismic and Magnetic Imager onboard Solar Dynamics Observatory), and VIS/GST (Visible Imaging Spectrometer at Goode Solar Telescope), demonstrate a complicated nature of evaporation and its connection to the magnetic field topology. …

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A Tight Relation Between Spiral Arm Pitch Angle And Protplanetary Disk Mass, Si-Yue Yu, Luis C. Ho, Zhaohuan Zhu May 2019

A Tight Relation Between Spiral Arm Pitch Angle And Protplanetary Disk Mass, Si-Yue Yu, Luis C. Ho, Zhaohuan Zhu

Physics & Astronomy Faculty Research

We use two-dimensional Fourier transformation to measure the pitch angle () of the dominant spiral Fourier mode of well-defined spiral arms in 13 protoplanetary disks, making use of near-infrared scattered-light images of AB Aur, SAO 206462, MWC 758, V1247 Ori, HD 142527, DZ Cha, LkHα 330, and HD 100453, and ALMA millimeter continuum images of Elias 2-27, IM Lup, AS 205, and HT Lup. We find that the measured pitch angle correlates strongly with disk mass (M D ), such that more massive protoplanetary disks have smaller pitch angles, following . Interestingly, four disks with a known companion (HD 142527, …

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A Hard Look At Ngc 5347: Revealing A Nearby Compton-Thick Agn, E. S. Kammoun, J. M. Miller, A. Zoghbi, K. Oh, M. Koss, R. F. Muchotzky, L. W. Brenneman, W. N. Brandt, Daniel Proga, A. M. Lohfink, J. S. Kaastra, D. Barret, E. Behar, D. Stern May 2019

A Hard Look At Ngc 5347: Revealing A Nearby Compton-Thick Agn, E. S. Kammoun, J. M. Miller, A. Zoghbi, K. Oh, M. Koss, R. F. Muchotzky, L. W. Brenneman, W. N. Brandt, Daniel Proga, A. M. Lohfink, J. S. Kaastra, D. Barret, E. Behar, D. Stern

Physics & Astronomy Faculty Research

Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC 5347 (z = 0.00792, D = 35.5 Mpc ) have alternately suggested a CT and Compton-thin source. Combining archival data from Suzaku, Chandra, and—most importantly—new data from NuSTAR, ... See full text for complete abstract

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Long-Term Dust Formation By Core Collapse Supernovae, Kelsie Marie Krafton May 2019

Long-Term Dust Formation By Core Collapse Supernovae, Kelsie Marie Krafton

LSU Doctoral Dissertations

Studying long-term dust formation by CCSNe is an important step toward understanding the large dust masses found in early galaxies. The amazing new discovery of approximately a solar mass of cold dust in the ejecta of SN 1987A has caused a complete re-evaluation of dust formation in core collapse supernovae (CCSNe). CCSNe form only a small amount of dust after three years, but SN 1987A has a dust mass that is several orders of magnitude larger after 25 years. A recent study of SN 2010jl by Gall et al. (2014) made the fascinating suggestion that dust is continuously forming in …

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One Solution To The Mass Budget Problem For Planet Formation: Optically Thick Disks With Dust Scattering, Zhaohuan Zhu, Shangjia Zhang, Yan-Fei Jiang, Akimasa Kataoka, Tilman Birnstiel, Cornelis P. Dullemond, Sean M. Andrews, Jane Huang, Laura M. Perez, John M. Carpenter, Xue-Ning Bai, David J. Wilner, Luca Ricci May 2019

One Solution To The Mass Budget Problem For Planet Formation: Optically Thick Disks With Dust Scattering, Zhaohuan Zhu, Shangjia Zhang, Yan-Fei Jiang, Akimasa Kataoka, Tilman Birnstiel, Cornelis P. Dullemond, Sean M. Andrews, Jane Huang, Laura M. Perez, John M. Carpenter, Xue-Ning Bai, David J. Wilner, Luca Ricci

Physics & Astronomy Faculty Research

Atacama Large Millimeter Array (ALMA) surveys have suggested that the dust in Class II disks may not be enough to explain the averaged solid mass in exoplanets, under the assumption that the mm disk continuum emission is optically thin. This optically thin assumption seems to be supported by recent Disk Substructures at High Angular Resolution Project (DSHARP) observations where the measured optical depths are mostly less than one. However, we point out that dust scattering can considerably reduce the emission from an optically thick region. If that scattering is ignored, an optically thick disk with scattering can be misidentified as …

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Galaxy Classification: A Machine Learning Analysis Of Gama Catalogue Data, Aleke Nolte, Lingyu Wang, Maciej Bilicki, Benne W. Holwerda, Michael Biehl May 2019

Galaxy Classification: A Machine Learning Analysis Of Gama Catalogue Data, Aleke Nolte, Lingyu Wang, Maciej Bilicki, Benne W. Holwerda, Michael Biehl

Faculty and Staff Scholarship

We present a machine learning analysis of five labelled galaxy catalogues from the Galaxy And Mass Assembly (GAMA): The SersicCatVIKING and SersicCatUKIDSS catalogues containing morphological features, the GaussFitSimplecatalogue containing spectroscopic features, the MagPhys catalogue including physical parameters for galaxies, and the Lambdar catalogue, which contains photometric measurements. Extending work previously presented at the ESANN 2018 conference – in an analysis based on Generalized Relevance Matrix Learning Vector Quantization and Random Forests – we find that neither the data from the individual catalogues nor a combined dataset based on all 5 catalogues fully supports the visual-inspection-based galaxy classification scheme employed to …

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