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Articles 31 - 60 of 256
Full-Text Articles in Astrophysics and Astronomy
Improving The Conductivity Of Graphite-Based Films By Rapid Laser Annealing, Gulsum Ersu, Sruthi Kuriakose, Stuart J. Goldie, Abdullah M. Al-Enizi, Ayman Nafady, Carmen Munuera, Claudia Backes, Joshua O. Island, Andres Castellanos-Gomez
Improving The Conductivity Of Graphite-Based Films By Rapid Laser Annealing, Gulsum Ersu, Sruthi Kuriakose, Stuart J. Goldie, Abdullah M. Al-Enizi, Ayman Nafady, Carmen Munuera, Claudia Backes, Joshua O. Island, Andres Castellanos-Gomez
Physics & Astronomy Faculty Research
We present a method to anneal devices based on graphite films on paper and polycarbonate substrates. The devices are created using four different methods: spray-on films, graphite pencil-drawn films, liquid-phase exfoliated graphite films, and graphite powder abrasion-applied films. We characterize the optical properties of the films before and after laser annealing and report the two-terminal resistance of the devices for increased laser power density. We find the greatest improvement (16× reduction) in the resistance of spray-on film devices starting from 25.0 kΩ and reaching 1.6 kΩ at the highest annealing power densities. These improvements are attributed to local laser ablation …
An Automated System For Strain Engineering And Straintronics Of 2d Materials, Onur Çakıroğlu, Joshua O. Island, Yong Xie, Riccardo Frisenda, Andres Castellanos-Gomez
An Automated System For Strain Engineering And Straintronics Of 2d Materials, Onur Çakıroğlu, Joshua O. Island, Yong Xie, Riccardo Frisenda, Andres Castellanos-Gomez
Physics & Astronomy Faculty Research
This work presents an automated three-point bending apparatus that can be used to study strain engineering and straintronics in 2D materials. This work benchmarks the system by reporting reproducible strain tuned micro-reflectance, Raman, and photoluminescence spectra for monolayer molybdenum disulfide (MoS2). These results are in good agreement with reported literature using conventional bending apparatus. This work further utilizes the system to automate strain investigations of straintronic devices by measuring the piezoresistive effect and the strain effect on photoresponse in an MoS2 electrical device. The details of the construction of the straightforward system are given and it is anticipated that it …
Polar Alignment Of Massive Retrograde Circumbinary Discs, Charles Abod
Polar Alignment Of Massive Retrograde Circumbinary Discs, Charles Abod
UNLV Theses, Dissertations, Professional Papers, and Capstones
To understand the observed circumbinary planetary systems, we must first explain the dynamics of the circumbinary discs in which they formed. Observations of circumbinary discs show that misalignments to the binary orbital plane may be common. Here we investigate these systems by exploring the orbital dynamics of three-body systems and circumbinary discs. A test particle orbit around an eccentric binary has two stationary states in which there is no nodal precession: coplanar and polar. Nodal precession of a misaligned test particle orbit centres on one of these stationary states. A low mass circumbinary disc undergoes the same precession and moves …
The Disk Of Fu Orionis Viewed With Matisse/Vlti: First Interferometric Observations In L And M Bands, Foteini Lykou, P. Ábrahám, L. Chen, J. Varga, Á. Kóspál, A. Matter, M. Siwak, Zs. M. Szabo, Z. Zhu, H. B. Liu, B. Lopez, F. Allouche, J.-C. Augereau, P. Berio, P. Cruzalebes, C. Dominik, Th Henning, K.-H. Hofmann, M. Hogerheijde, W. J. Jaffe, E. Kokulina, S. Lagarde, A. Meilland, F. Millour, E. Pantin, R. Petrov, S. Robbe-Dubois, D. Schertl, M. Scheuck, R. Van Boekel, L. B. F. M. Waters, G. Weigelt, S. Wolf
The Disk Of Fu Orionis Viewed With Matisse/Vlti: First Interferometric Observations In L And M Bands, Foteini Lykou, P. Ábrahám, L. Chen, J. Varga, Á. Kóspál, A. Matter, M. Siwak, Zs. M. Szabo, Z. Zhu, H. B. Liu, B. Lopez, F. Allouche, J.-C. Augereau, P. Berio, P. Cruzalebes, C. Dominik, Th Henning, K.-H. Hofmann, M. Hogerheijde, W. J. Jaffe, E. Kokulina, S. Lagarde, A. Meilland, F. Millour, E. Pantin, R. Petrov, S. Robbe-Dubois, D. Schertl, M. Scheuck, R. Van Boekel, L. B. F. M. Waters, G. Weigelt, S. Wolf
Physics & Astronomy Faculty Research
Aims. We studied the accretion disk of the archetypal eruptive young star FU Orionis with the use of mid-infrared interferometry, which enabled us to resolve the innermost regions of the disk down to a spatial resolution of 3 milliarcseconds (mas) in the L band, that is, within 1 au of the protostar. Methods. We used the interferometric instrument MATISSE/VLTI to obtain observations of FU Ori’s disk in the L, M, and N bands with multiple baseline configurations. We also obtained contemporaneous photometry in the optical (UBVRIri ; SAAO and Konkoly Observatory) and near-infrared (JHKs; NOT). Our results were compared with …
A Repeating Fast Radio Burst Associated With A Persistent Radio Source, C.-H. Niu, K. Aggarwal, D. Li, X. Zhang, S. Chatterjee, C.-W. Tsai, W. Yu, C. J. Law, S. Burke-Spolaor, J. M. Cordes, Y.-K. Zhang, S. K. Ocker, J.-M. Yao, P. Wang, Y. Feng, Y. Niino, C. Bochenek, M. Cruces, L. Connor, J.-A. Jiang, S. Dai, R. Luo, G.-D. Li, C.-C. Miao, J.-R. Niu, R. Anna-Thomas, J. Sydnor, D. Stern, W.-Y. Wang, M Yuan, Y.-L. Yue, D.-J. Zhou, Z Yan, W.-W. Zhu, B. Zhang
A Repeating Fast Radio Burst Associated With A Persistent Radio Source, C.-H. Niu, K. Aggarwal, D. Li, X. Zhang, S. Chatterjee, C.-W. Tsai, W. Yu, C. J. Law, S. Burke-Spolaor, J. M. Cordes, Y.-K. Zhang, S. K. Ocker, J.-M. Yao, P. Wang, Y. Feng, Y. Niino, C. Bochenek, M. Cruces, L. Connor, J.-A. Jiang, S. Dai, R. Luo, G.-D. Li, C.-C. Miao, J.-R. Niu, R. Anna-Thomas, J. Sydnor, D. Stern, W.-Y. Wang, M Yuan, Y.-L. Yue, D.-J. Zhou, Z Yan, W.-W. Zhu, B. Zhang
Physics & Astronomy Faculty Research
The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium1, which is assumed to dominate the total extragalactic dispersion. Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs2, in at least one case there is evidence for an extreme magneto-ionic local environment3,4 and a compact persistent radio source5. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift …
Physics Of Electromagnetic Counterparts Of Binary-Neutron-Star Mergers, Shunke Ai
Physics Of Electromagnetic Counterparts Of Binary-Neutron-Star Mergers, Shunke Ai
UNLV Theses, Dissertations, Professional Papers, and Capstones
Binary neutron star (BNS) mergers are supposed to be the sources of a variety of astrophysical transients, including both gravitational wave (GW) and electromagnetic (EM) signals. The types and properties of the post-merger central product contain crucial information for many unsolved physical problems. Since the current GW detectors are not sensitive enough in kHz, only GWs from the inspiral phase can be detected, so that one cannot directly study the central products from GWs. EM signals can serve as probes to infer the type and properties of the central product. When a long-lived neutron star (NS) is formed after the …
Dust-Gas Dynamics Driven By The Streaming Instability With Various Pressure Gradients, Stanley Antedio Baronett
Dust-Gas Dynamics Driven By The Streaming Instability With Various Pressure Gradients, Stanley Antedio Baronett
UNLV Theses, Dissertations, Professional Papers, and Capstones
The radial pressure gradient (RPG), along the midplane of gaseous protoplanetary disks (PPD) – planetary nurseries – poses a severe obstacle to planet formation. Micron-sized dust grains, embedded in the disc, must quickly grow to kilometer-sized planetesimals – the building blocks of planets – before fatally drifting inwards, by RPG-induced gas drag, into a central host star. However, the RPG simultaneously powers one of the most robust processes to overcome this radial-drift barrier: the streaming instability (SI). Spontaneously triggered, the SI aerodynamically concentrates drifting dust via drag-induced, coupled interactions and feedback with the surrounding gas. In particular, the non-linear phase …
The Effects Of Winds On Accretion Disks And Spectra Of X-Ray Binaries And Active Galactic Nuclei, Shalini Ganguly
The Effects Of Winds On Accretion Disks And Spectra Of X-Ray Binaries And Active Galactic Nuclei, Shalini Ganguly
UNLV Theses, Dissertations, Professional Papers, and Capstones
Active galactic nuclei (AGNs) and X-ray binaries (XRBs) contain at their cores supermassive black holes (SMBH), and stellar mass black holes or neutron stars, respectively. These objects bind matter gravitationally, leading to the formation of accretion disks. The accretion of matter leads to efficient conversion of gravitational potential energy into radiation. When the force and/or energy imparted by this radiation on matter exceeds the attractive force due to the local gravitational field, it leads to the launching of matter in the form of outflows or winds. These outflows produce blueshifted (and occasionally redshifted) emission or absorption components in the spectra …
Miocene Ichnofaunas And Mammalian Communities In The Great Basin Region, Nevada And California, Annmarie R. Jones
Miocene Ichnofaunas And Mammalian Communities In The Great Basin Region, Nevada And California, Annmarie R. Jones
UNLV Theses, Dissertations, Professional Papers, and Capstones
The purpose of this dissertation is to document and interpret three new ichnofaunas and two fossil assemblages from the Neogene of Nevada and California. Ichnofossils are important for understanding behavior and geographical range of animals in the distant past and are key to locating and preserving sensitive material for future studies. I examined ichnofauna at three localities: two within the Mio-Pliocene Muddy Creek Formation of Nevada, and one within the Miocene China Ranch Beds of California. My research focuses primarily on (1) camelid and ursid ichnotaxa and how these new localities help in understanding the evolutionary history of these taxa …
Viability Of Energy And Fuel Sources For Interstellar Travel; Design And Feasibility Of The Construction Of Manned Interstellar Space Shuttles, Lukas Mittelman
Viability Of Energy And Fuel Sources For Interstellar Travel; Design And Feasibility Of The Construction Of Manned Interstellar Space Shuttles, Lukas Mittelman
UNLV Theses, Dissertations, Professional Papers, and Capstones
The importance of proving the viability of interstellar transport and addressing its potential hazards and pitfalls is immense. If we do not look toward the future and examine what could be waiting for us, we are doing our children, our children’s children, and so on, a disservice. Here we must attempt to lay the groundwork for our future scientists, engineers, and adventurers. Asking and answering questions like, which propulsion and energy systems must we incorporate to send us through the cosmos? Will we utilize technologies known today, such as fossil fuel rockets, fission or fusion rockets, and antimatter drives (pion …
Terrestrial Planet Formation In M-Dwarf And Binary Star Systems, Anna C. Childs
Terrestrial Planet Formation In M-Dwarf And Binary Star Systems, Anna C. Childs
UNLV Theses, Dissertations, Professional Papers, and Capstones
I examine circumbinary terrestrial planet formation in a gas free environment around various binary systems and terrestrial planet formation in a gaseous environment around M-dwarfs. While terrestrial cirumbinary planets have yet to be observed, this is likely due to observational bias. Motivated by recent observations of highly misaligned circumbinary gas disks, I perform a suite of n-body studies to understand the properties of terrestrial planets around various binary systems. In a polar alignment, a circumbinary disk is inclined by 90 degrees relative to the binary orbital plane. I find that terrestrial planet formation in a polar configuration may be as …
Expanding The Library Of Planet Building Materials In Magrathea, Rosalie Chaleunsouck, Tristan Benally
Expanding The Library Of Planet Building Materials In Magrathea, Rosalie Chaleunsouck, Tristan Benally
Undergraduate Research Symposium Posters
Exoplanets are often modeled with fully-differentiated layers of iron, silicates, water, and gas. The large pressure and temperature ranges within each layer results in changes of phase and mineral equilibrium. MAGRATHEA is an open-course planet interior structure code with a large library of equations of state for planet building materials. This allows for the user to build detailed planet models and test differing measurements of the equation of state. We extend MAGRATHEA's library to include upper-mantle materials and various phases of iron cores. We show the impact of these materials on the characterization of rocky planet interiors.
Microbial Life In Deep-Subsurface Environments: The Role Of High Pressure In Biogeochemical Cycles, Cheyenne Brokaw
Microbial Life In Deep-Subsurface Environments: The Role Of High Pressure In Biogeochemical Cycles, Cheyenne Brokaw
Undergraduate Research Symposium Posters
Ocean World: An ocean world is considered any planet or moon currently with a liquid ocean. While the deepest part of the Ocean (Mariana Trench, 11,000 mbsl, 110 Mpa) and the lithosphere host microbial life, it begs the question, How?
Validation Of Accelerometry As A Digital Phenotyping Measure Of Negative Symptoms In Schizophrenia, Gregory P. Strauss, Ian M. Raugh, Luyu Zhang, Lauren Luther, Hannah C. Chapman, Daniel N. Allen, Brian Kirkpatrick, Alex S. Cohen
Validation Of Accelerometry As A Digital Phenotyping Measure Of Negative Symptoms In Schizophrenia, Gregory P. Strauss, Ian M. Raugh, Luyu Zhang, Lauren Luther, Hannah C. Chapman, Daniel N. Allen, Brian Kirkpatrick, Alex S. Cohen
Physics & Astronomy Faculty Research
Negative symptoms are commonly assessed via clinical rating scales; however, these measures have several inherent limitations that impact validity and utility for their use in clinical trials. Objective digital phenotyping measures that overcome some of these limitations are now available. The current study evaluated the validity of accelerometry (ACL), a passive digital phenotyping method that involves collecting data on the presence, vigor, and variability of movement. Outpatients with schizophrenia (SZ: n = 50) and demographically matched healthy controls (CN: n = 70) had ACL continuously recorded from a smartphone and smartband for 6 days. Active digital phenotyping assessments, including surveys …
Temporal Scattering, Depolarization, And Persistent Radio Emission From Magnetized Inhomogeneous Environments Near Repeating Fast Radio Burst Sources, Yuan-Pei Yang, Wenbin Lu, Yi Feng, Bing Zhang, Di Li
Temporal Scattering, Depolarization, And Persistent Radio Emission From Magnetized Inhomogeneous Environments Near Repeating Fast Radio Burst Sources, Yuan-Pei Yang, Wenbin Lu, Yi Feng, Bing Zhang, Di Li
Physics & Astronomy Faculty Research
Some repeating fast radio burst (FRB) sources exhibit complex polarization behaviors, including frequencydependent depolarization, variation of rotation measure (RM), and oscillating spectral structures of polarized components. Very recently, Feng et al. reported that active repeaters exhibit conspicuous frequency-dependent depolarization and a strong correlation between RM scatter (σRM) and the temporal scattering time (τs), s s 1.0 0.2, both of which can be well described by multipath propagation through a magnetized inhomogeneous plasma screen. This observation strongly suggests that the temporal scattering and RM scatter originate from the same region. Besides, a particular finding of note in Feng et al. is …
Investigating The Future Potential Of An Upgraded Alma To Image Planet-Forming Disks At Sub-Astronomical-Unit Scales, Benjamin P. Burrill, Luca Ricci, Sarah K. Harter, Shangjia Zhang, Zhaohuan Zhu
Investigating The Future Potential Of An Upgraded Alma To Image Planet-Forming Disks At Sub-Astronomical-Unit Scales, Benjamin P. Burrill, Luca Ricci, Sarah K. Harter, Shangjia Zhang, Zhaohuan Zhu
Physics & Astronomy Faculty Research
In recent years, ALMA has been able to observe large-scale substructures within protoplanetary disks. Comparison with the predictions from models of planet–disk interactions has indicated that most of these disk substructures can be explained by the presence of planets with the mass of Neptune or larger at orbital radii of ≈5–100 au. Better resolution is needed to observe structures closer to the star, where terrestrial planets are expected to form, as well as structures opened by planets with masses lower than Neptune. We investigate the capabilities of a possible extension to ALMA that would double the longest baseline lengths in …
Dark Fluxes From Accreting Black Holes Through Several Mechanisms, Rong-Gen Cai, Sichun Sun, Bing Zhang, Yun-Long Zhang
Dark Fluxes From Accreting Black Holes Through Several Mechanisms, Rong-Gen Cai, Sichun Sun, Bing Zhang, Yun-Long Zhang
Physics & Astronomy Faculty Research
We discuss the possibility that accreting black hole systems can be sources for dark matter flux through several different mechanisms. We firstly discuss two types of systems‘: coronal thermal plasmas around supermassive black holes in active galactic nuclei (AGNs), and accretion disks of stellar-mass X-ray black hole binaries (BHBs). We explore how these black hole systems may produce keV light dark matter fluxes and find that the dark fluxes from those sources might be too weak to account for the current XENON1T excess. On the other hand, black holes can be good accelerators to accrete and boost heavy dark matter …
Circumbinary Disk Evolution In The Presence Of An Outer Companion Star, Rebecca G. Marin, Stephen Lepp, Stephen H. Lubow, Matthew A. Kenworthy, Grant M. Kennedy, David Vallet
Circumbinary Disk Evolution In The Presence Of An Outer Companion Star, Rebecca G. Marin, Stephen Lepp, Stephen H. Lubow, Matthew A. Kenworthy, Grant M. Kennedy, David Vallet
Physics & Astronomy Faculty Research
We consider a hierarchical triple system consisting of an inner eccentric binary with an outer companion. A highly misaligned circumbinary disk around the inner binary is subject to two competing effects: (i) nodal precession about the inner binary eccentricity vector that leads to an increase in misalignment (polar alignment) and (ii) Kozai–Lidov (KL) oscillations of eccentricity and inclination driven by the outer companion that leads to a reduction in the misalignment. The outcome depends upon the ratio of the timescales of these effects. If the inner binary torque dominates, then the disk aligns to a polar orientation. If the outer …
Macroscale Robust Superlubricity On Metallic Nbb2, Jia Wang, Chang Liu, Kaifei Miao, Kan Zhang, Weitao Zheng, Changfeng Chen
Macroscale Robust Superlubricity On Metallic Nbb2, Jia Wang, Chang Liu, Kaifei Miao, Kan Zhang, Weitao Zheng, Changfeng Chen
Physics & Astronomy Faculty Research
Robust superlubricity (RSL), defined by concurrent superlow friction and wear, holds great promise for reducing material and energy loss in vast industrial and technological operations. Despite recent advances, challenges remain in finding materials that exhibit RSL on macrolength and time scales and possess vigorous electrical conduction ability. Here, the discovery of RSL is reported on hydrated NbB2 films that exhibit vanishingly small coefficient of friction (0.001–0.006) and superlow wear rate (≈10−17 m3 N−1 m−1) on large length scales reaching millimeter range and prolonged time scales lasting through extensive loading durations. Moreover, the measured low resistivity (≈10−6 Ω m) of the …
Misalignment Of Terrestrial Circumbinary Planets As An Indicator Of Their Formation Mechanism, Anna C. Childs, Rebecca G. Martin
Misalignment Of Terrestrial Circumbinary Planets As An Indicator Of Their Formation Mechanism, Anna C. Childs, Rebecca G. Martin
Physics & Astronomy Faculty Research
Circumbinary gas disks are often observed to be misaligned with the binary orbit, suggesting that planet formation may proceed in a misaligned disk. With n-body simulations, we consider the formation of circumbinary terrestrial planets from a particle disk that is initially misaligned. We find that if terrestrial planets form in this way, in the absence of gas, they can only form close to coplanar or close to polar to the binary orbit. Planets around a circular binary form coplanar while planets around an eccentric binary can form coplanar or polar depending on the initial disk misalignment and the binary eccentricity. …
Asteroids And Life: How Special Is The Solar System?, Rebecca G. Martin, Mario Livio
Asteroids And Life: How Special Is The Solar System?, Rebecca G. Martin, Mario Livio
Physics & Astronomy Faculty Research
Asteroid impacts with Earth may have played an essential role in the emergence of life on Earth through their creation of favorable niches for life, changes to the atmosphere, and delivery of water. Consequently, we suggest two potential requirements for life in an exoplanetary system: first, that the system has an asteroid belt, and second, that there is a mechanism to drive asteroids to impact the terrestrial habitable planet. Since in the solar system the ν6 secular resonance has been shown to have been important in driving these impacts, we explore how the masses and locations of two giant planets …
Eccentric Dust-Ring Formation In Kozai-Lidov Gas Disks, Rebecca G. Martin, Stephen H. Lubow
Eccentric Dust-Ring Formation In Kozai-Lidov Gas Disks, Rebecca G. Martin, Stephen H. Lubow
Physics & Astronomy Faculty Research
A highly misaligned gas disk around one component of a binary star system can undergo global Kozai-Lidov (KL) oscillations for which the disk inclination and eccentricity are exchanged. With hydrodynamical simulations of a gas and dust disk we explore the effects of these oscillations on the dust density distribution. For dust that is marginally coupled to the gas (St ≈ 1), we find that the dust undergoes dynamical behavior similar to that of the gas disk but the radial distribution of dust may be very different from that of the gas. The inward radial drift of the dust is faster …
Stability And Mechanical Properties Of W1-X Mox B4.2 (X=0.0-1.0) From First Principles, Weiguang Gong, Rui Xu, Xuecheng Shao, Quan Li, Changfeng Chen
Stability And Mechanical Properties Of W1-X Mox B4.2 (X=0.0-1.0) From First Principles, Weiguang Gong, Rui Xu, Xuecheng Shao, Quan Li, Changfeng Chen
Physics & Astronomy Faculty Research
Heavy transition-metal tetraborides (e.g., tungsten tetraboride, molybdenum tetraboride, and molybdenum-doped tungsten tetraboride) exhibit superior mechanical properties, but solving their complex crystal structures has been a long-standing challenge. Recent experimental x-ray and neutron diffraction measurements combined with first-principles structural searches have identified a complex structure model for tungsten tetraboride that contains a boron trimer as an unusual structural unit with a stoichiometry of 1:4.2. In this paper, we expand the study to binary MoB4.2 and ternary W1-xMoxB4.2 (x=0.0-1.0) compounds to assess their thermodynamic stability and mechanical properties using a tailor-designed crystal structure search method in conjunction with first-principles energetic calculations. Our …
Eccentric Neutron Star Disk Driven Type Ii Outburst Pairs In Be/X-Ray Binaries, Alessia Franchini, Rebecca G. Martin
Eccentric Neutron Star Disk Driven Type Ii Outburst Pairs In Be/X-Ray Binaries, Alessia Franchini, Rebecca G. Martin
Physics & Astronomy Faculty Research
Be star X-ray binaries are transient systems that show two different types of outbursts. Type I outbursts occur each orbital period while type II outbursts have a period and duration that are not related to any periodicity of the binary system. Type II outbursts may be caused by mass transfer to the neutron star from a highly eccentric Be star disk. A sufficiently misaligned Be star decretion disk undergoes secular Von Zeipel-Lidov-Kozai (ZLK) oscillations of eccentricity and inclination. Observations show that in some systems the type II outbursts come in pairs with the second being of lower luminosity. We use …
Nonperiodic Type I Be/X-Ray Binary Outbursts, Rebecca G. Martin, Alessia Franchini
Nonperiodic Type I Be/X-Ray Binary Outbursts, Rebecca G. Martin, Alessia Franchini
Physics & Astronomy Faculty Research
Type I Be/X-ray binary outbursts are driven by mass transfer from a Be star decretion disk to a neutron star companion during each orbital period. Treiber et al. recently observed nonperiodic type I outbursts in RX J0529.8-6556 that has unknown binary orbital properties. We show that nonperiodic type I outbursts may be temporarily driven in a low eccentricity binary with a disk that is inclined sufficiently to be mildly unstable to Kozai-Lidov oscillations. The inclined disk becomes eccentric and material is transferred to the neutron star at up to three locations in each orbit: when the neutron star passes the …
Global 3d Radiation Hydrodynamic Simulations Of Proto-Jupiter’S Convective Envelope, Zhaohuan Zhu, Yan-Fei Jiang, Hans Baehr, Andrew N. Youdin, Philip J. Armitage, Rebecca G. Martin
Global 3d Radiation Hydrodynamic Simulations Of Proto-Jupiter’S Convective Envelope, Zhaohuan Zhu, Yan-Fei Jiang, Hans Baehr, Andrew N. Youdin, Philip J. Armitage, Rebecca G. Martin
Physics & Astronomy Faculty Research
The core accretion model of giant planet formation has been challenged by the discovery of recycling flows between the planetary envelope and the disc that can slow or stall envelope accretion. We carry out 3D radiation hydrodynamic simulations with an updated opacity compilation to model the proto-Jupiter’s envelope. To isolate the 3D effects of convection and recycling, we simulate both isolated spherical envelopes and envelopes embedded in discs. The envelopes are heated at given rates to achieve steady states, enabling comparisons with 1D models. We vary envelope properties to obtain both radiative and convective solutions. Using a passive scalar, we …
Multi-Messenger Astrophysics With Theseus In The 2030s, Bing Zhang, Numerous Authors, See Full List Below
Multi-Messenger Astrophysics With Theseus In The 2030s, Bing Zhang, Numerous Authors, See Full List Below
Physics & Astronomy Faculty Research
Multi-messenger astrophysics is becoming a major avenue to explore the Universe, with the potential to span a vast range of redshifts. The growing synergies between different probes is opening new frontiers, which promise profound insights into several aspects of fundamental physics and cosmology. In this context, THESEUS will play a central role during the 2030s in detecting and localizing the electromagnetic counterparts of gravitational wave and neutrino sources that the unprecedented sensitivity of next generation detectors will discover at much higher rates than the present. Here, we review the most important target signals from multi-messenger sources that THESEUS will be …
Initial Acoustoelastic Measurements In Olivine: Investigating The Effect Of Stress On P- And S-Wave Velocities, Taryn K. Traylor, Pamela C. Burnley, M. L. Whitaker
Initial Acoustoelastic Measurements In Olivine: Investigating The Effect Of Stress On P- And S-Wave Velocities, Taryn K. Traylor, Pamela C. Burnley, M. L. Whitaker
Geoscience Faculty Research
It is well known that elasticity is a key physical property in the determination of the structure and composition of the Earth and provides critical information for the interpretation of seismic data. This study investigates the stress-induced variation in elastic wave velocities, known as the acoustoelastic effect, in San Carlos olivine. A recently developed experimental ultrasonic acoustic system, the Directly Integrated Acoustic System Combined with Pressure Experiments (DIASCoPE), was used with the D-DIA multi-anvil apparatus to transmit ultrasonic sound waves and collect the reflections. We use the DIASCoPE to obtain longitudinal (P) and shear (S) elastic wave velocities from San …
Gw Ori: Circumtriple Rings And Planets, Jeremy L. Smallwood, Rebecca Nealon, Cheng Chen, Rebecca G. Martin, Jiaqing Bi, Ruobing Dong, Christophe Pinte
Gw Ori: Circumtriple Rings And Planets, Jeremy L. Smallwood, Rebecca Nealon, Cheng Chen, Rebecca G. Martin, Jiaqing Bi, Ruobing Dong, Christophe Pinte
Physics & Astronomy Faculty Research
GW Ori is a hierarchical triple star system with a misaligned circumtriple protoplanetary disc. Recent Atacama Large Millimeter/submillimeter Array observations have identified three dust rings with a prominent gap at 100 au and misalignments between each of the rings. A break in the gas disc may be driven by the torque from either the triple star system or a planet that is massive enough to carve a gap in the disc. Once the disc is broken, the rings nodally precess on different time-scales and become misaligned. We investigate the origins of the dust rings by means of N-body integrations and …
Inelastic, Exchange, And Reactive Processes In Rovibrationally Excited Collisions Of Hd With H, Boyi Zhou, Benhui Yang, Balakrishnan Naduvalath, B. K. Kendrick, Maodu Chen, P. C. Stancil
Inelastic, Exchange, And Reactive Processes In Rovibrationally Excited Collisions Of Hd With H, Boyi Zhou, Benhui Yang, Balakrishnan Naduvalath, B. K. Kendrick, Maodu Chen, P. C. Stancil
Chemistry and Biochemistry Faculty Research
The HD molecule is an important coolant in early universe chemistry models and a tracer of H2 in star-forming regions. Rate coefficients for collisional excitation and de-excitation of HD rotational and vibrational levels form important ingredients in astrophysical models. While collisions with He, H2, and H are the most important, available data for H + HD collisions are largely limited to temperatures less than 1000 K for the vibrational ground state, low-lying rotational levels of the v = 1 HD vibrational level, or computed without reactive contributions. Here, through explicit quantum scattering calculations, we report extensive data for rovibrational transitions …