Astrophysics and Astronomy Commons^™

James Webb Space Telescope's Enlightening Journey Is Underway, Erik Johnson

Natural Science Faculty

A rocket carrying the successor to the Hubble Space Telescope launched on Christmas. Astronomers hope that the James Webb Space Telescope will provide insight about the earliest stage of the universe when it orbits about one million miles from Earth. The Staerkel Planetarium collaborated with the Illinois Space Grant Consortium to promote the launch of this revolutionary device.

Search For Continuous Gravitational Waves From 20 Accreting Millisecond X-Ray Pulsars In O3 Ligo Data, Ligo Scientific Collaboration, Virgo Collaboration, Kagra Collaboration, Tiffany Z. Summerscales

Faculty Publications

Results are presented of searches for continuous gravitational waves from 20 accreting millisecond x-ray pulsars with accurately measured spin frequencies and orbital parameters, using data from the third observing run of the Advanced LIGO and Advanced Virgo detectors. The search algorithm uses a hidden Markov model, where the transition probabilities allow the frequency to wander according to an unbiased random walk, while the J-statistic maximum-likelihood matched filter tracks the binary orbital phase. Three narrow subbands are searched for each target, centered on harmonics of the measured spin frequency. The search yields 16 candidates, consistent with a false alarm probability of …

Coupling Between Alfvén Wave And Kelvin–Helmholtz Waves In The Low Latitude Boundary Layer, Eun-Hwa Kim, Jay R. Johnson

Faculty Publications

The Kelvin–Helmholtz (KH) instability of magnetohydrodynamic surface waves at the low latitude boundary layer is examined using both an eigenfrequency analysis and a time-dependent wave simulation. The analysis includes the effects of sheared flow and Alfvén velocity gradient. When the magnetosheath flows are perpendicular to the ambient magnetic field direction, unstable KH waves that propagate obliquely to the sheared flow direction occur at the sheared flow surface when the Alfvén Mach number is higher than an instability threshold. Including a shear transition layer between the magnetosphere and magnetosheath leads to secondary KH waves (driven by the sheared flow) that are …

Comparison Of Maximum-Likelihood Mapping Methods For Gravitational-Wave Backgrounds, Arianna I. Renzini, Joseph D. Romano, Carlo R. Contaldi, Neil Cornish

Physics & Astronomy Faculty Publications

Detection of a stochastic background of gravitational waves is likely to occur in the next few years. Beyond searches for the isotropic component of a stochastic gravitational-wave background, there have been various mapping methods proposed to target anisotropic backgrounds. Some of these methods have been applied to data taken by the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo. Specifically, these directional searches have focused on mapping the intensity of the signal on the sky via maximum-likelihood solutions. We compare this intensity mapping approach to a previously proposed, but never employed, amplitude-phase mapping method to understand whether this latter approach may …

Towards A Quantum Notion Of Covariance In Spherically Symmetric Loop Quantum Gravity, Rodolfo Gambini, Javier Olmedo, Jorge Pullin

Faculty Publications

The covariance of loop quantum gravity studies of spherically symmetric space-times has recently been questioned. This is a reasonable worry, given that they are formulated in terms of slicing-dependent variables. We show explicitly that the resulting space-times, obtained from Dirac observables of the quantum theory, are covariant in the usual sense of the way-they preserve the quantum line element-for any gauge that is stationary (in the exterior, if there is a horizon). The construction depends crucially on the details of the Abelianized quantization considered, the satisfaction of the quantum constraints, and the recovery of standard general relativity in the classical …

Towards A Quantum Notion Of Covariance In Spherically Symmetric Loop Quantum Gravity, Rodolfo Gambini, Javier Olmedo, Jorge Pullin

Faculty Publications

The covariance of loop quantum gravity studies of spherically symmetric space-times has recently been questioned. This is a reasonable worry, given that they are formulated in terms of slicing-dependent variables. We show explicitly that the resulting space-times, obtained from Dirac observables of the quantum theory, are covariant in the usual sense of the way-they preserve the quantum line element-for any gauge that is stationary (in the exterior, if there is a horizon). The construction depends crucially on the details of the Abelianized quantization considered, the satisfaction of the quantum constraints, and the recovery of standard general relativity in the classical …

Dr. Jennifer Hoffman, Anit Tyagi

DU Undergraduate Research Journal Archive

An interview with Dr. Jennifer Hoffman.

Dark And Quiet Skies Ii Working Group Reports, James Lowenthal, Connie Walker, Piero Benvenuti

Astronomy: Faculty Publications

This Report presents the main results of the Conference “Dark and Quiet Skies for Science and Society II” which took place on-line on 3–7 October 2021. This conference was the logical follow-up of the first one, organized as an on-line workshop with the same title on 5–9 October 2020. Both conferences were co-organized by UNOOSA, IAU and the Government of Spain and were well attended. The focus of the second conference was about the feasibility of implementing the recommendations presented by the first one in its extensive report. The main qualifying difference between the first and the second conferences was …

Measurements Of The Electron-Helicity Asymmetry In The Quasi-Elastic A ((E) Over Right Arrow, E' O) Process, T. Kolar, S. J. Paul, P. Achenbach, H. Arenhoevel, A. Ashkenazi, J. Beričič, R. Böhm, D. Bosnar, T. Brecelj, E. Cline, E. O. Cohen, M. O. Distler, A. Esser, I. Friščić, R. Gilman, C. Giusti, M. Heilig, M. Hoek, D, Izraeli, Steffen Strauch, Et. Al.

Faculty Publications

We present measurements of the electron helicity asymmetry in quasi-elastic proton knockout from ²H and ¹²C nuclei by polarized electrons. This asymmetry depends on the fifth structure function, is antisymmetric with respect to the scattering plane, and vanishes in the absence of final-state interactions, and thus it provides a sensitive tool for their study. Our kinematics cover the full range in off-coplanarity angle θ_pq, with a polar angle θ_pq coverage up to about 8^◦. The missing energy resolution enabled us to determine the asymmetries for knock-out resulting in different states of the residual …

Characterization Of Ti/Sno2 Interface By X-Ray Photoelectron Spectroscopy, Miranda Martinez, Chourasia R. Anil

Faculty Publications

The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced …

Deep Extragalactic Visible Legacy Survey: Data Release 1 Blended Spectra Search For Candidate Strong Gravitational Lenses, Benne Holwerda, S Knabel, J E. Thorne, S Bellstedt, M Siudek, L J M Davies

Faculty and Staff Scholarship

Here, we present a catalogue of blended spectra in Data Release 1 of the Deep Extragalactic VIsible Legacy Survey (DEVILS) on the Anglo-Australian Telescope. Of the 23 197 spectra, 181 showed signs of a blend of redshifts and spectral templates. We examine these blends in detail for signs of either a candidate strong lensing galaxy or a useful overlapping galaxy pair. One of the three DEVILS target fields, COSMOS (D10), is close to complete and it is fully imaged with Hubble Space Telescope Advanced Camera for Surveys, and we visually examine the 57 blended spectra in this field in the …

Design, Construction And Operation Of The Protodune-Sp Liquid Argon Tpc, The Dune Collaboration, A. Abed Abud, B. Abi, R. Acciarri, M. A. Acero, M. R. Adames, G. Adamov, D. Adams, M. Adinolfi, A. Aduszkiewicz, J. Aguilar, Z. Ahmad, J. Ahmed, B. Ali-Mohammadzadeh, T. Alion, K. Allison, S. Alonso Monsalve, M. Alrashed, C. Alt, A. Alton, Roberto Petti, Et. Al.

Faculty Publications

The ProtoDUNE-SP detector is a single-phase liquid argon time projection chamber (LArTPC) that was constructed and operated in the CERN North Area at the end of the H4 beamline. This detector is a prototype for the first far detector module of the Deep Underground Neutrino Experiment (DUNE), which will be constructed at the Sandford Underground Research Facility (SURF) in Lead, South Dakota, U.S.A. The ProtoDUNE-SP detector incorporates full-size components as designed for DUNE and has an active volume of 7 × 6 × 7.2 m³. The H4 beam delivers incident particles with well-measured momenta and high-purity particle identification. …

Individual Element Sensitivity For Stellar Evolutionary Isochrones, Guy Worthey, Xiang Shi, Tathagata Pal, Hyun-Chul Lee, Baitian Tang

Physics & Astronomy Faculty Publications

Stellar evolution calculations with variable abundance ratios were used to gauge the effects on temperatures, luminosities, and lifetimes in various phases. The individual elements C, N, O, Mg, Si, and Fe were included. Most of the effect relevant to integrated light models is contained in the temperature variable, as opposed to the time-scale or luminosity. We derive a recipe for including abundance-sensitive temperature effects that is applicable to existing isochrone grids. The resultant enhanced isochrones are incorporated into composite stellar population models and compared with galaxy data from the Sloan Digital Sky Survey. A severe oxygen–age degeneracy is apparent, 2–3 …

Study Of B ¯ 0 →D+H- (H=K/Π) Decays At Belle Study Of B ¯ 0 →D+H- (H=K/Π) ... Waheed E. Et Al., E. Waheed, P. Urquijo, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, S. Bahinipati, P. Behera, K. Belous, J. Bennett, M. Bessner, V. Bhardwaj, B. Bhuyan, T. Bilka, J. Biswal, A. Bobrov

Faculty and Student Publications

We present a measurement of the branching fractions of the Cabibbo favored B¯0→D+π- and the Cabibbo suppressed B¯0→D+K- decays. We find B(B¯0→D+π-)=(2.48±0.01±0.09±0.04)×10-3 and B(B¯0→D+K-)=(2.03±0.05±0.07±0.03)×10-4 decays, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the D+→K-π+π+ branching fraction. The ratio of branching fractions of B¯0→D+K- and B¯0→D+π- is measured to be RD=[8.19±0.20(stat)±0.23(syst)]×10-2. These measurements are performed using the full Belle dataset, which corresponds to 772×106BB¯ pairs and use the Belle II software framework for data analysis.

Biographical Calendars Of Astronomers [January - December], Thomas A. Hockey

Data Sets

A set of twelve biographical calendars of astronomers for each month of the year (January through December). History of astronomy (public outreach).

Record contents:

• Main Download button - A merged Excel file with all 12 months
• Additional Files section - Individual Excel files for each month [January - December]

A Search For Analogs Of Kic 8462852 (Boyajian’S Star): A Second List Of Candidates, Edward G. Schmidt

Edward Schmidt Publications

In data from the Kepler mission, the normal F3V star KIC 8462852 (Boyajian’s star) was observed to exhibit infrequent dips in brightness that have not been satisfactorily explained. A previous paper reported the first results of a search for other similar stars in a limited region of the sky around the Kepler field. This paper expands on that search to cover the entire sky between declinations of +22°and +68°. Fifteen new candidates with low rates of dipping, referred to as “slow dippers” in Paper I, have been identified. The dippers occupy a limited region of the HR diagram and an …

The Differentialgeometry Package, Ian M. Anderson, Charles G. Torre

Downloads

This is the entire DifferentialGeometry package, a zip file (DifferentialGeometry.zip) containing (1) a Maple Library file, DifferentialGeometryUSU.mla, (2) a Maple help file DifferentialGeometry.help, (3) a Maple Library file, DGApplicatons.mla. This is the latest version of the DifferentialGeometry software; it supersedes what is released with Maple.

Installation instructions

Search For The Decay Bs0 →Ηη, B. Bhuyan, K. J. Nath, J. Borah, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, I. Badhrees, A. M. Bakich, P. Behera, J. Bennett, V. Bhardwaj, T. Bilka, J. Biswal

Faculty and Student Publications

We report results from a search for the decay Bs0→ηη using 121.4 fb-1 of data collected at the (5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We do not observe any signal and set an upper limit on the branching fraction of 14.3×10-5 at 90% confidence level. This result represents a significant improvement over the previous most stringent limit.

A New Non-Inheriting Homogeneous Solution Of The Einstein-Maxwell Equations With Cosmological Term, Charles G. Torre

Research Vignettes

No abstract provided.

The Meaning Of Dark, Light And Shadows: Inferences In Art, Materiality And Cultural Practices, Frank Prendergast

Book/Book Chapter

Our visual awareness relies on light acting on the eye to perceive materiality and colour. Medieval thought wrestled to articulate and comprehend its nature. The notebooks of Leonardo Da Vinci, for example, included his descriptions to define light and make comparisons so as to differentiate between light and shadow. His focus was on the illumination of surfaces from the perspective of a painter, seeing shadows as ‘the diminution of light by the intervention of an opaque body’ and ‘the counterpart of luminous rays’. In his mind, a shadow ‘stood between light and darkness’, with darkness being ‘the absence of light’. …

A New Non-Inheriting Homogeneous Solution Of The Einstein-Maxwell Equations With Cosmological Term, Ian M. Anderson, Charles G. Torre

Publications

We find a new homogeneous solution to the Einstein-Maxwell equations with a cos- mological term. The spacetime manifold is R × S3. The spacetime metric admits a simply transitive isometry group G = R × SU(2) and is Petrov type I. The spacetime is geodesically complete and globally hyperbolic. The electromagnetic field is non- null and non-inheriting: it is only invariant with respect to the SU(2) subgroup and is time-dependent in a stationary reference frame.

Formation Of Contact Binary Stars: Magnetic Braking, Lau Jenn Feng, Levi Carr, Larry A. Molnar

Summer Research

No abstract provided.

A New Universal Polarization Resolving Software Package For Solar Coronal And Heliospheric Observations, Bryce M. Walbridge, Matthew J. West, J. Marcus Hughes, Dan Seaton, Chris Lowder

Summer Research

No abstract provided.

Measurement Of B (Bs →Dsx) With Bs Semileptonic Tagging, B. Wang, K. Kinoshita, H. Aihara, D. M. Asner, T. Aushev, R. Ayad, V. Babu, I. Badhrees, A. M. Bakich, P. Behera, C. Beleño, J. Bennett, M. Bessner, V. Bhardwaj, T. Bilka, J. Biswal, A. Bobrov, G. Bonvicini, A. Bozek

Faculty and Student Publications

We report the first direct measurement of the inclusive branching fraction B(Bs→DsX) via Bs tagging in e+e-→ (5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays Bs→DsXℓν, where X denotes unreconstructed additional hadrons or photons and ℓ is an electron or muon. With 121.4 fb-1 of data collected at the (5S) resonance by the Belle detector at the KEKB asymmetric-energy e+e- collider, we obtain B(Bs→DsX)=(60.2±5.8±2.3)%, where the first uncertainty is statistical and the second is systematic.

Toi-2257 B: A Highly Eccentric Long-Period Sub-Neptune Transiting A Nearby M Dwarf, N. Schanche, F. J. Pozuelos, M. N. Günther, R. D. Wells, A. J. Burgasser, P. Chinchilla, L. Delrez, E. Ducrot, L. J. Garcia, Y. Gómez Maqueo Chew, E. Jofré, B. V. Rackham, D. Sebastian, K. G. Stassun, D. Stern, M. Timmermans, K. Barkaoui, A. Belinski, Z. Benkhaldoun, W. Benz, A. Bieryla, F. Bouchy, A. Burdanov, D. Charbonneau, J. L. Christiansen, K. A. Collins, B.-O. Demory, M. Dévora-Pajares, J. De Wit, D. Dragomir, G. Dransfield, E. Furlan, M. Ghachoui, M. Gillon, C. Gnilka, M. A. Gómez-Muñoz, N. Guerrero, M. Harris, K. Heng, C. E. Henze, K. Hesse, S. B. Howell, E. Jehin, J. Jenkins, Eric L.N. Jensen, M. Kunimoto, D. W. Latham, K. Lester, K. K. Mcleod, I. Mireles, C. A. Murray, P. Niraula, P. P. Pedersen, D. Queloz, E. V. Quintana, G. Ricker, A. Rudat, L. Sabin, B. Safonov, U. Schroffenegger, N. Scott, S. Seager, I. Strakhov, A. H. M. J. Triaud, R. Vanderspek, M. Vezie, J. Winn

Physics & Astronomy Faculty Works

Context. Thanks to the relative ease of finding and characterizing small planets around M-dwarf stars, these objects have become cornerstones in the field of exoplanet studies. The current paucity of planets in long-period orbits around M dwarfs makes such objects particularly compelling as they provide clues about the formation and evolution of these systems. Aims. In this study we present the discovery of TOI-2257 b (TIC 198485881), a long-period (35 d) sub-Neptune orbiting an M3 star at 57.8 pc. Its transit depth is about 0.4%, large enough to be detected with medium-size, ground-based telescopes. The long transit duration …

Extremely Broad Ly Α Line Emission From The Molecular Intragroup Medium In Stephan's Quintet: Evidence For A Turbulent Cascade In A Highly Clumpy Multiphase Medium?, P. Guillard, P. N. Appleton, F. Boulanger, J. M. Shull, M. D. Lehnert, G. Pineau Des Forets, E. Falgarone, M. E. Cluver, C. K. Xu, Sarah C. Gallagher, P. A. Duc

Physics and Astronomy Publications

We present Hubble Space Telescope Cosmic Origin Spectrograph (COS) UV line spectroscopy and integral-field unit (IFU) observations of the intragroup medium in Stephan's Quintet (SQ). SQ hosts a 30 kpc long shocked ridge triggered by a galaxy collision at a relative velocity of 1000 km s-1, where large amounts of molecular gas coexist with a hot, X-ray-emitting, plasma. COS spectroscopy at five positions sampling the diverse environments of the SQ intragroup medium reveals very broad (≈2000 km s-1) Lyα line emission with complex line shapes. The Lyα line profiles are similar to or much broader than those of Hβ, [C …

What's New In Differentialgeometry Release Dg2022, Ian M. Anderson, Charles G. Torre

Tutorials on... in 1 hour or less

This Maple worksheet demonstrates the salient new features and functionalities of the 2022 release of the DifferentialGeometry software package.

Formation Of Contact Binary Stars: 1) Kozai Cycles With Tidal Friction, Levi Carr, Lau Jenn Feng, Larry A. Molnar

Summer Research

A binary star is a system that contains two stars orbiting each other. A contact binary is a binary star whose component stars are so close that they share the same atmosphere (see Figure 1 on far right). They are the most common kind of eclipsing binary stars. Critical questions to be answered are: how do they form, how do they survive for a long time, and how do they ultimately die? This summer’s work focused on the first of those questions. A process is needed to bring a widely separated binary into contact. It has been suggested this requires …

Physical Characteristics And Classification Of The Large Amplitude Variable Star V1719 Cygni, Ashley Lieber, Logan Siems, Julia Kennefick, Michael Fitzgerald

Inquiry: The University of Arkansas Undergraduate Research Journal

Pulsating stars are used as standard candles which are helpful in determining distances to stellar objects along with the relationship between their period and apparent luminosity. The focus of this study was the variable star, V1719 Cygni, which is often classified as a Delta (δ) Scuti star, but there exists debate that it should be classified as a RR Lyrae star due to its abnormal light curve and similar characteristics between the two variable star categories. Observational data was taken in 2019 using the Las Cumbres Observatory international telescope network. The resulting data were calibrated using comparison stars in the …

Athena Detector Proposal — A Totally Hermetic Electron Nucleus Apparatus Proposed For Ip6 At The Electron-Ion Collider, The Athena Collaboration

Physics and Astronomy Faculty Publications

ATHENA has been designed as a general purpose detector capable of delivering the full scientific scope of the Electron-Ion Collider. Careful technology choices provide fine tracking and momentum resolution, high performance electromagnetic and hadronic calorimetry, hadron identification over a wide kinematic range, and near-complete hermeticity. This article describes the detector design and its expected performance in the most relevant physics channels. It includes an evaluation of detector technology choices, the technical challenges to realizing the detector and the R&D required to meet those challenges.