# Astrophysics and Astronomy Commons™

## All Articles in Astrophysics and Astronomy

6,250 full-text articles. Page 7 of 189.

How Many Quasars Have Extremely High Velocity Outflows?, 2018 Humboldt State University

#### How Many Quasars Have Extremely High Velocity Outflows?, Carla P. Quintero, Sean S. Haas, Paola Rodriguez Hidalgo

##### IdeaFest: Interdisciplinary Journal of Creative Works and Research from Humboldt State University

No abstract provided.

Searching For A Connection Between Radio Emission And Uv/Optical Absorption In Quasars, 2018 Humboldt State University

#### Searching For A Connection Between Radio Emission And Uv/Optical Absorption In Quasars, Sean S. Haas, Carla P. Quintero, Paola Rodriguez Hidalgo

##### IdeaFest: Interdisciplinary Journal of Creative Works and Research from Humboldt State University

No abstract provided.

Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary - Ii. Effect Of Binary And Disc Parameters, 2018 University of Nevada, Las Vegas

#### Polar Alignment Of A Protoplanetary Disc Around An Eccentric Binary - Ii. Effect Of Binary And Disc Parameters, Rebecca G. Martin, Stephen H. Lubow

##### Physics & Astronomy Faculty Publications

In a recent paper Martin & Lubow showed that a circumbinary disc around an eccentric binary can undergo damped nodal oscillations that lead to the polar (perpendicular) alignment of the disc relative to the binary orbit. The disc angular momentum vector aligns to the eccentricity vector of the binary. We explore the robustness of this mechanism for a low-mass disc (0.001 of the binary mass) and its dependence on system parameters by means of hydrodynamic disc simulations. We describe how the evolution depends upon the disc viscosity, temperature, size, binary mass ratio, orbital eccentricity, and inclination. We compare results with ...

The Eccentric Cavity, Triple Rings, Two-Armed Spirals, And Double Clumps Of The Mwc 758 Disk, 2018 University of Arizona; Academia Sinica

#### The Eccentric Cavity, Triple Rings, Two-Armed Spirals, And Double Clumps Of The Mwc 758 Disk, Ruobing Dong, Sheng-Yuan Liu, Josh Eisner, Sean Andrews, Jeffrey Fung, Zhauhuan Zhu, Eugene Chiang, Jun Hashimoto, Hauyu Baobab Liu, Simon Casassus, Thomas Esposito, Yasuhiro Hasegawa, Takayuki Muto, Yaroslav Pavlyuchenkov, David Wilner, Eiji Akiyama, Motohide Tamura, John Wisniewski

##### Physics & Astronomy Faculty Publications

Spatially resolved structures in protoplanetary disks hint at unseen planets. Previous imaging observations of the transitional disk around MWC 758 revealed an inner cavity, a ring-like outer disk, emission clumps, and spiral arms, all possibly generated by companions. We present ALMA dust continuum observations of MWC 758 at 0.87 mm wavelength with 43 × 39 mas angular resolution (6.9 × 6.2 au) and 20 μJy beam−1 rms. The central submillimeter emission cavity is revealed to be eccentric; once deprojected, its outer edge can be well fitted by an ellipse with an eccentricity of 0.1 and one focus ...

How Middle Level Science Teachers Visualize And Translate Motion, Scale, And Geometric Space Of The Earth-Moon-Sun System With Their Students, 2018 University of Kentucky

#### How Middle Level Science Teachers Visualize And Translate Motion, Scale, And Geometric Space Of The Earth-Moon-Sun System With Their Students, Jennifer Wilhelm, Merryn Cole, Cheryl Cohen, Rebecca Lindell

##### Science, Technology, Engineering, and Mathematics (STEM) Education Faculty Publications

[This paper is part of the Focused Collection on Astronomy Education Research.] We examined teachers’ spatial-scientific reasoning and the alternative conceptions they held regarding Earth-space content. While participating in a professional development (PD) workshop, teachers engaged in an integrated mathematics and science project-based unit designed to foster spatial reasoning and improve lunar-related conceptual understanding. The Purdue Spatial Visualization Test-Rotation (PSVT-Rot) and the Lunar Phases Concept Inventory (LPCI) were used to assess understanding. We found the teachers held similar alternative conceptions as their students. Moreover, we discovered that teachers had limited understanding of the Earth-Moon-Sun scale, motions, and geometric configurations. To ...

Spatial Thinking In Astronomy Education Research, 2018 University of Nevada - Las Vegas

#### Spatial Thinking In Astronomy Education Research, Merryn Cole, Cheryl Cole, Jennifer Wilhelm, Rebecca Lindell

##### Science, Technology, Engineering, and Mathematics (STEM) Education Faculty Publications

This paper is part of the Focused Collection on Astronomy Education Research.] Multiple studies show that spatial thinking skills contribute to students’ performance in science, technology, engineering, and mathematics disciplines. The study of astronomy is no different with the understanding of many astronomical phenomena requiring spatial thinking skills. This paper describes traditional and contemporary approaches to characterizing and measuring spatial thinking skills and suggests how they inform research in astronomy education. It summarizes previous literature in astronomy education research and categorizes the research approaches of astronomy education peer-reviewed journal articles and conference proceedings that explicitly consider the role of spatial ...

Mapping The Neutrino Floor For Direct Detection Experiments Based On Dark Matter-Electron Scattering, 2018 Dordt College

#### Mapping The Neutrino Floor For Direct Detection Experiments Based On Dark Matter-Electron Scattering, Jason Wyenberg, Ian M. Shoemaker

##### Faculty Work Comprehensive List

We study the discovery reach of future Dark Matter (DM) Direct Detection experiments using DM-electron scattering in the presence of the solar neutrino background. At these low energies traditional methods for nuclear and electronic recoil discrimination fail, implying that the neutrino- nucleusscattering background can be sizable. We calculate discovery limits based on ionization values of signal and background, and quantify the dependence on the ionization model. Moreover, we explore how the dependence of the DM cross section discovery limits varies with exposure, electronic/nuclear recoil discrimination, DM form factors, and DM astrophysical uncertainties.

The Origin Of The Prompt Emission For Short Grb 170817a: Photosphere Emission Or Synchrotron Emission?, 2018 Chinese Academy of Sciences

#### The Origin Of The Prompt Emission For Short Grb 170817a: Photosphere Emission Or Synchrotron Emission?, Yan-Zhi Meng, Jin-Jun Geng, Bin-Bin Zhang, Jun-Jie Wei, Di Xiao, Liang-Duan Liu, He Gao, Xue-Feng Wu, En-Wei Liang, Yong-Feng Huang, Zi-Gao Dai, Bing Zhang

##### Physics & Astronomy Faculty Publications

The first gravitational-wave event from the merger of a binary neutron star system (GW170817) was detected recently. The associated short gamma-ray burst (GRB 170817A) has a low isotropic luminosity (~1047 erg s−1) and a peak energy E p ~ 145 keV during the initial main emission between −0.3 and 0.4 s. The origin of this short GRB is still under debate, but a plausible interpretation is that it is due to the off-axis emission from a structured jet. We consider two possibilities. First, since the best-fit spectral model for the main pulse of GRB 170817A is a cutoff ...

The Allowed Parameter Space Of A Long-Lived Neutron Star As The Merger Remnant Of Gw170817, 2018 Beijing Normal University

#### The Allowed Parameter Space Of A Long-Lived Neutron Star As The Merger Remnant Of Gw170817, Shunke Ai, He Gao, Zi-Gao Dai, Xue-Feng Wu, Ang Li, Bing Zhang, Mu-Zi Li

##### Physics & Astronomy Faculty Publications

Due to the limited sensitivity of the current gravitational wave (GW) detectors, the central remnant of the binary neutron star (NS) merger associated with GW170817 remains an open question. In view of the relatively large total mass, it is generally proposed that the merger of GW170817 would lead to a short-lived hypermassive NS or directly produce a black hole (BH). There is no clear evidence to support or rule out a long-lived NS as the merger remnant. Here, we utilize the GW and electromagnetic (EM) signals to comprehensively investigate the parameter space that allows a long-lived NS to survive as ...

On The Radio Detectability Of Circumplanetary Discs, 2018 University of Nevada, Las Vegas

#### On The Radio Detectability Of Circumplanetary Discs, Zhaohuan Zhu, Sean M. Andrews, Andrea Isella

##### Physics & Astronomy Faculty Publications

Discs around young planets, so-called circumplanetary discs (CPDs), are essential for planet growth, satellite formation, and planet detection. We study the millimetre and centimetre emission from accreting CPDs by using the simple α disc model. We find that it is easier to detect CPDs at shorter radio wavelengths (e.g. λ ≲ 1 mm). For example, if the system is 140 pc away from us, deep observations (e.g. 5 h) at ALMA Band 7 (0.87 mm) are sensitive to as small as 0.03 lunar mass of dust in CPDs. If the CPD is around a Jupiter mass planet ...

Automation And Enhancements To The Erau Oscom System Space Situational Awareness, 2018 Embry-Riddle Aeronautical University

#### Automation And Enhancements To The Erau Oscom System Space Situational Awareness, Sergei Bilardi, Patrick Rupp, Yevgeniy Lischuk, Joseph Stroup

OSCOM, Optical tracking and Spectral characterization of CubeSats for Operational Missions, is a system developed at Embry-Riddle Aeronautical University to produce time-resolved photometry of small satellites using commercial-off-the-shelf hardware. OSCOM has been able to observe resident space objects (RSOs) as small as CubeSats using a Celestron 11” RASA and a CMOS machine vision camera from Allied Vision. By obtaining photometric measurements of satellites, a light curve can be constructed and used to help determine satellite characteristics such as spin rate, satellite state, and even satellite attitude. To enhance the OSCOM system’s ability to observe small satellites, there is ongoing ...

Multiple Stellar Flybys Sculpting The Circumstellar Architecture In Rw Aurigae, 2018 Swarthmore College

#### Multiple Stellar Flybys Sculpting The Circumstellar Architecture In Rw Aurigae, J. E. Rodriguez, R. Loomis, S. Cabrit, T. H. Haworth, S. Facchini, C. Dougados, R. A. Booth, Eric L.N. Jensen, C. J. Clarke, K. G. Stassun, W. R. F. Dent, J. Pety

##### Physics & Astronomy Faculty Works

We present high-resolution ALMA Band 6 and 7 observations of the tidally disrupted protoplanetary disks of the RW Aurigae binary. Our observations reveal tidal streams in addition to the previously observed tidal arm around RW Aur A. The observed configuration of tidal streams surrounding RW Aur A and B is incompatible with a single star–disk tidal encounter, suggesting that the RW Aurigae system has undergone multiple flyby interactions. We also resolve the circumstellar disks around RW Aur A and B, with CO radii of 58 au and 38 au consistent with tidal truncation, and 2.5 times smaller dust ...

Grb 120729a: External Shock Origin For Both The Prompt Gamma-Ray Emission And Afterglow, 2018 Guangxi University

#### Grb 120729a: External Shock Origin For Both The Prompt Gamma-Ray Emission And Afterglow, Li-Ye Huang, Xiang-Gao Wang, Weikang Zheng, En-Wei Liang, Da-Bin Lin, Shi-Qing Zhong, Hai-Ming Zhang, Xiao-Li Huang, Alexi V. Filippenko, Bing Zhang

##### Physics & Astronomy Faculty Publications

Gamma-ray burst (GRB) 120729A was detected by Swift/BAT and Fermi/GBM, and then rapidly observed by Swift/XRT, Swift/UVOT, and ground-based telescopes. It had a single long and smooth \gamma-ray emission pulse, which extends continuously to the X-rays. We report Lick/KAIT observations of the source, and make temporal and spectral joint fits of the multiwavelength light curves of GRB 120729A. It exhibits achromatic light-curve behavior, consistent with the predictions of the external shock model. The light curves are decomposed into four typical phases: onset bump (Phase I), normal decay (Phase II), shallow decay (Phase III), and post-jet ...

Gamma-Ray Burst Jet Breaks Revisited, 2018 Guangxi University

#### Gamma-Ray Burst Jet Breaks Revisited, Xiang-Gao Wang, Bing Zhang, En-Wei Liang, Rui-Jing Liang, Da-Bin Lin, Jing Li, Long Li

##### Physics & Astronomy Faculty Publications

Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow light curve allows a measurement of the jet opening angle and true energetics of GRBs. In this paper, we re-investigate this problem using a large sample of GRBs that have an optical jet break that is consistent with being achromatic in the X-ray band. Our sample includes 99 GRBs from 1997 February to 2015 March that have optical and, for Swift GRBs, X-ray light curves that are consistent with the jet ...

2018 Embry-Riddle Aeronautical University

#### Book Review: Spectral Atlas For Amateur Astronomers: A Guide To The Spectra Of Astronomical Objects And Terrestrial Light Sources, T. D. Oswalt

##### Publications

This document is Dr. Oswalt’s review of Spectral Atlas for Amateur Astronomers: A Guide to the Spectra of Astronomical Objects and Terrestrial Light Sources by Richard Walker. Cambridge 2017, 277 p bibl index, 9781107165908 $89.99, 9781316731048$72.00

Spectroscopic Constants And Line Positions For Tio Singlet States, 2018 Old Dominion University

#### Spectroscopic Constants And Line Positions For Tio Singlet States, Dror M. Bittner, Peter F. Bernath

##### Chemistry & Biochemistry Faculty Publications

consistent set of spectroscopic constants for the a1Δ,d1Σ+,b1Π,c1Φ, and f1Δ states of 48Ti16O has been determined from analysis of the b1Π–a1Δ,b1Π–d1Σ+,c1Φ–a1Δ, and f1Δ–a1Δ systems. Three Fourier transform emission spectra have been used for the analysis. New bands of the b1Π–a1Δ and c1Φ–a1Δ systems have been fitted. The first analysis of the c ...

Kelvin-Helmholtz Instability: Lessons Learned And Ways Forward, 2018 European Space Agency

#### Kelvin-Helmholtz Instability: Lessons Learned And Ways Forward, A. Masson, K. Nykyri

##### Publications

The Kelvin–Helmholtz instability (KHI) is a ubiquitous phenomenon across the Universe, observed from 500 m deep in the oceans on Earth to the Orion molecular cloud. Over the past two decades, several space missions have enabled a leap forward in our understanding of this phenomenon at the Earth’s magnetopause. Key results obtained by these missions are first presented, with a special emphasis on Cluster and THEMIS. In particular, as an ideal instability, the KHI was not expected to produce mass transport. Simulations, later confirmed by spacecraft observations, indicate that plasma transport in Kelvin–Helmholtz (KH) vortices can arise ...

Contribution Of Hi-Bearing Ultra-Diffuse Galaxies To The Cosmic Number Density Of Galaxies, 2018 Instituto de Astrofísica de Andalucía

#### Contribution Of Hi-Bearing Ultra-Diffuse Galaxies To The Cosmic Number Density Of Galaxies, M. Jones, E. Papastergis, V. Pandya, L. Leisman, Aaron J. Romanowsky, L. Yung, R. Somerville, E. Adams

##### Faculty Publications

We estimate the cosmic number density of the recently identified class of HI-bearing ultra-diffuse sources (HUDs) based on the completeness limits of the ALFALFA survey. These objects have HI masses approximately in the range 8.5 < logMHI∕M⊙ < 9.5, average r-band surface brightnesses fainter than 24 mag arcsec−2, half-light radii greater than 1.5 kpc, and are separated from neighbours by at least 350 kpc. In this work we demonstrate that they contribute at most ~6% of the population of HI-bearing dwarfs detected by ALFALFA (with similar HI masses), have a total cosmic number density of (1.5 ± 0 ...

The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, 2018 Swinburne University of Technology

#### The Sluggs Survey: A Comparison Of Total-Mass Profiles Of Early-Type Galaxies From Observations And Cosmological Simulations, To ∼4 Effective Radii, Sabine Bellstedt, Duncan Forbes, Aaron Romanowsky, Rhea-Silvia Remus, Adam Stevens, Jean Brodie, Adriano Poci, Richard Mcdermid, Adebusola Alabi, Leonie Chevalier, Caitlin Adams, Anna Ferré-Mateu, Asher Wasserman, Viraj Pandya

##### Faculty Publications

We apply the Jeans Anisotropic Multi-Gaussian Expansion dynamical modelling method to SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey data of early-type galaxies in the stellar mass range 1010 < M*/M⊙ < 1011.6 that cover a large radial range of 0.1–4.0 effective radii. We combine SLUGGS and ATLAS3D data sets to model the total-mass profiles of a sample of 21 fast-rotator galaxies, utilizing a hyperparameter method to combine the two independent data sets. The total-mass density profile slope values derived for these galaxies are consistent with those measured in the inner regions of galaxies by other studies. Furthermore, the total-mass density slopes (γtot) appear to be universal over this broad stellar mass range, with an average value of γtot =  −2.24 ±  0.05 , i.e. slightly steeper than isothermal. We compare our results to model galaxies from the Magneticum and EAGLE cosmological hydrodynamic simulations, in order to probe the mechanisms that are responsible for varying total-mass density profile slopes. The simulated-galaxy slopes are shallower than the observed values by ∼0.3–0.5, indicating that the physical processes shaping the mass distributions of galaxies in cosmological simulations are still incomplete. For galaxies with M* > 1010.7 M⊙ in the Magneticum simulations, we identify a significant anticorrelation between total-mass density profile slopes and the fraction of stellar mass formed ex situ (i.e. accreted), whereas this anticorrelation is weaker for lower stellar masses, implying that the measured total-mass density slopes for low-mass galaxies are less likely to be determined by merger activity.

Anatomy Of The Ρ Resonance From Lattice Qcd At The Physical Point, 2018 Chinese Academy of Sciences, China

#### Anatomy Of The Ρ Resonance From Lattice Qcd At The Physical Point, Wei Sun, Andrei Alexandru, Ying Chen, Terrence Draper, Zhaofeng Liu, Yi-Bo Yang, Χqcd Collaboration

##### Physics and Astronomy Faculty Publications

We propose a strategy to access the qq component of the ρ resonance in lattice QCD.