Stars, Interstellar Medium and the Galaxy Commons^™

"Water Fountain" Masers In Proto-Planetary Nebulae, Patrick R. Latimer

2018 Award Winners

No abstract provided.

Remark On Vacuum Fluctuation As The Cause Of Universe Creation: Or How Neutrosophic Logic And Material Point Method May Resolve Dispute On The Origin Of The Universe Through Re-Reading Gen. 1:1-2, Florentin Smarandache, Victor Christianto

Branch Mathematics and Statistics Faculty and Staff Publications

Questions regarding the formation of the Universe and what was there before the existence of Early Universe have been great interest to mankind of all times. In recent decades, the Big Bang as described by the Lambda CDMStandard Model Cosmology has become widely accepted by majority of physics and cosmology communities. Among other things, we can cite A.A. Grib Pavlov who pointed out some problems of heavy particles creation out of vacuum and also other proposal of Creatio ex nihilo theory (CET). But the philosophical problems remain, as Vaas pointed out: Did the universe have a beginning or does it …

An Enigmatic Population Of Luminous Globular Clusters In A Galaxy Lacking Dark Matter, Pieter Van Dokkum, Yotam Cohen, Shany Danieli, J. Diederik Kruijssen, Aaron Romanowsky, Allison Merritt, Roberto Abraham, Jean Brodie, Charlie Conroy, Deborah Lokhorst, Lamiya Mowla, Ewan O'Sullivan, Jielai Zhang

Faculty Publications

We recently found an ultra diffuse galaxy (UDG) with a half-light radius of R e  = 2.2 kpc and little or no dark matter. The total mass of NGC1052–DF2 was measured from the radial velocities of bright compact objects that are associated with the galaxy. Here, we analyze these objects using a combination of Hubble Space Telescope (HST) imaging and Keck spectroscopy. Their average size is  pc and their average ellipticity is . From a stacked Keck spectrum we derive an age of 9 Gyr and a metallicity of [Fe/H] = −1.35 ± 0.12. Their properties are similar to ωCentauri, …

Multiwavelength Observations Of The Blazar Bl Lacertae: A New Fast Tev Gamma-Ray Flare, P. T. Reynolds, Et Al

Physical Sciences Publications

Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of ~2.3 hr and a decay time of ~36 min. The peak flux above 200 GeV …

Patterns Of Variation For The Sun And Sun-Like Stars, Richard R. Radick, G. Wesley Lockwood, Gregory W. Henry, Jeffrey C. Hall, Alexei A. Pevtsov

Information Systems and Engineering Management Research Publications

We compare patterns of variation for the Sun and 72 Sun-like stars by combining total and spectral solar irradiance measurements between 2003 and 2017 from the SORCE satellite, Strömgren b, y stellar photometry between 1993 and 2017 from Fairborn Observatory, and solar and stellar chromospheric Ca ii H+K emission observations between 1992 and 2016 from Lowell Observatory. The new data and their analysis strengthen the relationships found previously between chromospheric and brightness variability on the decadal timescale of the solar activity cycle. Both chromospheric H+K and photometric b, y variability among Sun-like stars are related to average chromospheric activity by …

Precise Ages Of Field Stars From White Dwarf Companions, M. Fouesneau, H-W. Rix, T. Von Hippel, D. W. Hogg, H. Tian

Publications

Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star’s physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can be measured from spectroscopy, but ages are very hard to determine. The situation is different if the MS star has a white dwarf (WD) companion and a known distance, as the age of such a binary system can then be determined precisely from the photometric properties of the cooling WD. As a pilot study for obtaining precise age determinations of field MS stars, we identify …

Where Is Oh And Does It Trace The Dark Molecular Gas (Dmg)?, Di Li, Ningyu Tang, Hiep Nguyen, J. R. Dawson, Carl Heiles, Duo Xu, Zhichen Pan, Paul F. Goldsmith, Steven J. Gibson, Claire E. Murray, Tim Robishaw, N. M. Mcclure-Griffiths, John Dickey, Jorge Pineda, Snežana Stanimirović, L. Bronfman, Thomas Troland

Physics and Astronomy Faculty Publications

Hydroxyl (OH) is expected to be abundant in diffuse interstellar molecular gas because it forms along with H₂ under similar conditions and forms within a similar extinction range.

For the remainder of the abstract, please download this article or visit: https://doi.org/10.3847/1538-4365/aaa762

Frb 121102: A Repeatedly Combed Neutron Star By A Nearby Low-Luminosity Accreting Supermassive Black Hole, Bing Zhang

Physics & Astronomy Faculty Research

The origin of fast radio bursts (FRBs) remains mysterious. Recently, the only repeating FRB source, FRB 121102, was reported to possess an extremely large and variable rotation measure (RM). The inferred magnetic field strength in the burst environment is comparable to that in the vicinity of the supermassive black hole Sagittarius A* of our Galaxy. Here, we show that all of the observational properties of FRB 121102 (including the high RM and its evolution, the high linear polarization degree, an invariant polarization angle across each burst and other properties previously known) can be interpreted within the "cosmic comb" model, which …

Direct Collapse To Supermassive Black Hole Seeds With Radiative Transfer: Isolated Halos, Yang Luo, Kazem Ardaneh, Isaac Shlosman, Kentaro Nagamine, John H. Wise, Mitchell C. Begelman

Physics and Astronomy Faculty Publications

Direct collapse within dark matter haloes is a promising path to form supermassive black hole seeds at high redshifts. The outer part of this collapse remains optically thin. However, the innermost region of the collapse is expected to become optically thick and requires to follow the radiation field in order to understand its evolution. So far, the adiabatic approximation has been used exclusively for this purpose. We apply radiative transfer in the flux-limited diffusion (FLD) approximation to solve the evolution of coupled gas and radiation for isolated haloes. We find that (1) the photosphere forms at 10⁻⁶ pc and …

A Disk Origin For The Monoceros Ring And A13 Stellar Overdensities, Allyson A. Sheffield, Adrian M. Price-Whelan, Anastasios Tzanidakis, Kathryn V. Johnston, Chervin F.P. Laporte, Branimir Sesar

Publications and Research

The Monoceros Ring (also known as the Galactic Anticenter Stellar Structure) and A13 are stellar overdensities at estimated heliocentric distances of d ~ 11 kpc and 15 kpc observed at low Galactic latitudes toward the anticenter of our Galaxy. While these overdensities were initially thought to be remnants of a tidally disrupted satellite galaxy, an alternate scenario is that they are composed of stars from the Milky Way (MW) disk kicked out to their current location due to interactions between a satellite galaxy and the disk. To test this scenario, we study the stellar populations of the Monoceros Ring and …

Thinking Out Loud On Primeval Atom, Big Bang & Biblical Account Of Creation, Florentin Smarandache, Victor Christianto

Branch Mathematics and Statistics Faculty and Staff Publications

In recent years, the Big Bang as described by the Lambda CDM-Standard Model Cosmology has become widely accepted by majority of physics and cosmology communities. Some people even have concluded that it has no serious alternative in horizon. Is that true? First, as we argued elsewhere, Big Bang relies on singularity, so, when we are able to describe the observed data without invoking singularity, then Big Bang model is no longer required. In this paper, we explore a few alternatives other than Big Bang which most cosmologists believe is the closest to biblical account of creation. We argue that re-reading …

A Young Solar Twin In The Rosette Cluster Ngc 2244 Line Of Sight, Jeremy M. Huber, John F. Kielkopf, Matthew Mengel, Bradley D. Carter, Gary J. Ferland, Frank O. Clark

Physics and Astronomy Faculty Publications

Based on prior precision photometry and cluster age analysis, the bright star GSC 00154−01819 is a possible young pre-main sequence member of the Rosette cluster, NGC 2244. As part of a comprehensive study of the large-scale structure of the Rosette and its excitation by the cluster stars, we noted this star as a potential backlight for a probe of the interstellar medium and extinction along the sight line towards a distinctive nebular feature projected on to the cluster centre. New high-resolution spectra of the star were taken with the University College London Echelle Spectrograph of the AAT. They reveal that …

Luminous And Obscured Quasars And Their Host Galaxies, Agnese Del Moro, David M. Alexander, Franz E. Bauer, Emanuele Daddi, Dale D. Kocevski, Flora Stanley, Daniel H. Mcintosh

Physics and Astronomy Faculty Publications

The most heavily-obscured, luminous quasars might represent a specific phase of the evolution of the actively accreting supermassive black holes and their host galaxies, possibly related to mergers. We investigated a sample of the most luminous quasars at z ≈ 1 − 3 in the GOODS fields, selected in the mid-infrared band through detailed spectral energy distribution (SED) decomposition. The vast majority of these quasars (~80%) are obscured in the X-ray band and ~30% of them to such an extent, that they are undetected in some of the deepest (2 and 4 Ms) Chandra X-ray data. Although no clear relation …

On The Formation Mechanisms Of Compact Elliptical Galaxies, Anna Ferré-Mateu, Duncan Forbes, Aaron Romanowsky, Joachim Janz, Christopher Dixon

Faculty Publications

In order to investigate the formation mechanisms of the rare compact elliptical (cE) galaxies, we have compiled a sample of 25 cEs with good SDSS spectra, covering a range of stellar masses, sizes and environments. They have been visually classified according to the interaction with their host, representing different evolutionary stages. We have included clearly disrupted galaxies, galaxies that despite not showing signs of interaction are located close to a massive neighbour (thus are good candidates for a stripping process), and cEs with no host nearby. For the latter, tidal stripping is less likely to have happened and instead they …

Thinking Out Loud On Early Creation Through The Lens Of Hermeneutics Of Sherlock Holmes (Towards A Model Of Universe Based On Turbulence-Generated Sound Theory), Victor Christianto, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

In recent years, apparently the Big Bang as described by the Lambda CDM-Standard Model Cosmology has become widely accepted by majority of physics and cosmology communities. Even some people have concluded that it has no serious alternative in horizon. Is that true? First, as we argued elsewhere, Big Bang story relies on singularity. In other words, when we are able to describe the observed data without invoking singularity, then Big Bang model is no longer required. Therefore, here we explore a few alternative stories other than Big Bang story, which most cosmologists believe it is the nearest to Biblical account …

Solar Eclipse, 2017 (Sc 3152), Manuscripts & Folklife Archives

Manuscript Collection Finding Aids

Finding aid only for Manuscripts Small Collection 3152. Materials relating to the 2017 solar eclipse as experienced primarily in Bowling Green and Hopkinsville, Kentucky and vicinity. Includes viewing glasses, first day stamped covers, stickers, art work, photographs (in digital format), promotional materials, and impressions of the eclipse contributed as part of WKU’s Department of Library Special Collections’ “Tell Us About Your Eclipse Day” project. Also includes wristbands, handouts and volunteer information relating to an eclipse viewing event for schoolchildren held at WKU’s Smith-Houchens Stadium. Digital photographs are stored in the Photo Archives.

Differential Rotation In Magnetic Chemically Peculiar Stars, Zdeněk Mikulášek, Jiří Krtička, Ernst Paunzen, Michal Švanda, Stefan Hummerich, Klaus Bernhard, Miroslav Jagelka, Jan Janík, Gregory W. Henry, Matthew E. Shultz

Information Systems and Engineering Management Research Publications

Magnetic chemically peculiar (mCP) stars constitute about 10% of upper-main-sequence stars and are characterized by strong magnetic fields and abnormal photospheric abundances of some chemical elements. Most of them exhibit strictly periodic light, magnetic, radio, and spectral variations that can be fully explained by a rigidly rotating main-sequence star with persistent surface structures and a stable global magnetic field. Long-term observations of the phase curves of these variations enable us to investigate possible surface differential rotation with unprecedented accuracy and reliability. The analysis of the phase curves in the best-observed mCP stars indicates that the location and the contrast of …

Effects Of Mass And Distance Uncertainties On Calculations Of Flux From Giant Molecular Clouds, Matt Coel

Dissertations, Master's Theses and Master's Reports

It is assumed that the distribution of the Milky Way cosmic rays, the cosmic ray ‘sea,’ is even throughout the Galaxy. This assumption can be tested by measuring gamma rays produced from cosmic ray interactions with Giant Molecular Clouds. The gamma ray flux depends on the mass and distance of a given molecular cloud as well as the cosmic ray flux in its vicinity. Thus a predicted gamma ray flux can be compared to actual flux data from a detector. Uncertainties from measuring the mass of and distance to the clouds are taken into account for this prediction. This report …

Study Of The Cygnus Region With Fermi And Hawc, Andrew Robare

Dissertations, Master's Theses and Master's Reports

The Cygnus Cocoon is an extended source of high-energy gamma-ray emission in the Cygnus region. The gamma-ray emission has been attributed to a volume 50pc in diameter of freshly-accelerated particles near the Supernova Remnant γ Cygni which is located 1.4kpc from the solar system [Ackermann et al., 2011], [Tibaldo et al., 2013]. Since its discovery in 2011, Fermi LAT has improved their event reconstruction to allow analysis at higher energies, and recorded six additional years of data. An analysis was performed on the entire dataset to reproduce the previous results, then expand on them with higher energies and larger time …

Multi-Telescope Radio Observations For Low Frequency Gravitational Wave Astrophysics, Megan L. Jones

Graduate Theses, Dissertations, and Problem Reports (ETD)

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has the principal goal of detecting gravitational waves (GWs) in the nanohertz part of the spectrum using pulsar timing. This thesis presents results from radio campaigns at frequencies from 322 MHz to 10 GHz aimed at both multi-messenger constraints on GW sources and improving the timing sensitivity. The primary expected source of GWs at the nanohertz frequencies to which pulsar timing is sensitive are supermassive black hole (SMBH) binaries. We investigate a purported SMBH displaced from the galactic photocenter in NGC 3115. We explore the possibilities that the source is a …

Rr Lyrae Calibration Using Sdss, Single-Epoch Spectroscopy, Stacy Long

Theses and Dissertations--Physics and Astronomy

I use single-epoch, SDSS spectroscopy of RR Lyraes identified in the Catalina survey to separate the spectra into same-temperature groups. Then I draw temperature-phase diagrams of the groups. I find shocked stars, improperly phased stars, low amplitude stars, and a few that are more likely eclipsing binaries. The RR Lyraes are then given precise metallicities by measurements of the CaII K and H-β, H-γ, and H-δ lines. This leads to better distance measurements, which allow me to confirm a distinction between the inner and outer galactic halo.

An Additional Pulsating Mode (7.35 Mhz) And Pulsations Timing Variations Of Pg 1613+426, Tomomi Otani, Terry D. Oswalt, Patrice Majewski, Riley Jordan, Marc Amaral, Adam Moss

Publications

We present the detection of an additional pulsation mode (7.35 mHz) of a subdwarf B star, PG 1613+426, and periodic Observed minus Calculated (O-C) variations for two existing pulsations. PG 1613+426 is near the hot end of the sdB instability strip. One pulsation mode (6.94 mHz) was detected so far by Bonanno et al. (2002) and another pulsation mode candidate (7.05 mHz) was proposed with a confidence level above 90% by Kuassivi and Ferlet (2005). To constrain sdB star evolutional scenarios, this star was monitored in 2010, 2011, 2015, and 2017 as a part of a project for finding companions …

Orbital Misalignment Of The Neptune-Mass Exoplanet Gj 436b With The Spin Of Its Cool Star, Vincent Bourrier, Christophe Lovis, Hervé Beust, David Ehrenreich, Gregory W. Henry, Nicola Astudillo-Defru, Romain Allart, Xavier Bonfils, Damien Ségransan, Xavier Delfosse, Heather M. Cegla, Aurélien Wyttenbach, Kevin Heng, Baptiste Lavie, Francesco Pepe

Information Systems and Engineering Management Research Publications

The angle between the spin of a star and the orbital planes of its planets traces the history of the planetary system. Exoplanets orbiting close to cool stars are expected to be on circular, aligned orbits because of strong tidal interactions with the stellar convective envelope. Spin–orbit alignment can be measured when the planet transits its star, but such ground-based spectroscopic measurements are challenging for cool, slowly rotating stars. Here we report the three-dimensional characterization of the trajectory of an exoplanet around an M dwarf star, derived by mapping the spectrum of the stellar photosphere along the chord transited by …

Unseen Science: Modern Discoveries Too Far Away Or Tiny For Human Eyes, Lucy Huang

Capstones

As science has progressed, scientists have realized that evidence goes beyond the realms of physical sight. Whether it is too small or difficult to find, scientists have developed different ways to get around this problem. We see this in cancer genomics and in extrasolar planetary research. Scientists use what they know and what they measure to validate their work.

https://lucy-huang-9tge.squarespace.com/

Nonlinear Gravity Wave Forcing As A Source Of Acoustic Waves In The Mesosphere, Thermosphere, And Ionosphere, J. B. Snively

Publications

Numerical simulations demonstrate theoretical predictions that gravity waves with short periods (∼4–8 min) in the mesosphere and lower thermosphere may force secondary acoustic waves, with harmonic periods (∼2-4 minutes), that can reach detectable amplitudes in the thermosphere and ionosphere. The mechanism is through their vertical fluxes of vertical momentum, which lead to forcing as they are disrupted by varying stratification or instability. This is shown likely to occur where horizontally or radially opposing gravity waves interact at large amplitudes, such as above large convective sources, and after overturning. Evanescence and reflection of the waves can lead to further enhancements of …

Energy From Active Galactic Nuclei And The Effects On Host Spiral Galaxies, Amanda Schilling

Graduate Theses and Dissertations

I have investigated the energy output of active galactic nuclei (AGN) in order to understand how these objects evolve and the impact they may have on host galaxies. First, I looked at a sample of 96 AGN at redshifts $z \sim 2, 3,$ and $4$ which have imaging and thus luminosity measurements in the $griz$ and $JHK$ observed wavebands. For these galaxies, I have co-epochal data across those bands which accounted for variability in AGN luminosity. I used the luminosity measurements in the five bands to construct spectral energy distributions (SED) in the emitted optical-UV bands for each AGN. I …

Deep Subaru Hyper Suprime-Cam Observations Of Milky Way Satellites Columba I And Triangulum Ii*, Jeffrey Carlin, David Sand, Ricardo Muñoz, Kristine Spekkens, Beth Willman, Denija Crnojević, Duncan Forbes, Jonathan Hargis, Evan Kirby, Annika Peter, Aaron Romanowsky, Jay Strader

Faculty Publications

We present deep, wide-field Subaru Hyper Suprime-Cam photometry of two recently discovered satellites of the Milky Way (MW): Columba I (Col I) and Triangulum II (Tri II). The color–magnitude diagrams of both objects point to exclusively old and metal-poor stellar populations. We re-derive structural parameters and luminosities of these satellites, and find  for Col I and  for Tri II, with corresponding half-light radii of  pc and  pc. The properties of both systems are consistent with observed scaling relations for MW dwarf galaxies. Based on archival data, we derive upper limits on the neutral gas content of these dwarfs, and find …

An X-Ray Study Of Two B+B Binaries: Ah Cep And Cw Cep, Richard Ignace, K. T. Hole, Lidia M. Oskinova, J. P. Rotter

ETSU Faculty Works

AH Cep and CW Cep are both early B-type binaries with short orbital periods of 1.8 days and 2.7 days, respectively. All four components are B0.5V types. The binaries are also double-lined spectroscopic and eclipsing. Consequently, solutions for orbital and stellar parameters make the pair of binaries ideal targets for a study of the colliding winds between two B stars. Chandra ACIS-I observations were obtained to determine X-ray luminosities. AH Cep was detected with an unabsorbed X-ray luminosity at a 90% confidence interval of erg s−1, or , relative to the combined Bolometric luminosities of the two components. While formally …

Initial Mass Function Variability (Or Not) Among Low-Velocity Dispersion, Compact Stellar Systems, Alexa Villaume, Jean Brodie, Charlie Conroy, Aaron Romanowsky, Pieter Van Dokkum

Faculty Publications

Analyses of strong gravitational lenses, galaxy-scale kinematics, and absorption-line stellar population synthesis (SPS) have all concluded that the stellar initial mass function (IMF) varies within the massive early-type galaxy (ETG) population. However, the physical mechanism that drives variation in the IMF is an outstanding question. Here we use new SPS models to consider a diverse set of compact, low-velocity dispersion stellar systems: globular clusters (GCs), an ultra-compact dwarf (UCD), and the compact elliptical (cE) galaxy M32. We compare our results to massive ETGs and available dynamical measurements. We find that the GCs have stellar mass-to-light ratios (M/L) that are either …

Discovery Of Very-High-Energy Emission From Rgb J2243+203 And Derivation Of Its Redshift Upper Limit, P. T. Reynolds, Et Al

Physical Sciences Publications

Very-high-energy (VHE; > 100 GeV) gamma-ray emission from the blazar RGB J2243+203 was discovered with the VERITAS Cherenkov telescope array, during the period between 2014 December 21 and 24. The VERITAS energy spectrum from this source can be fitted by a power law with a photon index of 4.6 ± 0.5, and a flux normalization at 0.15 TeV of . The integrated Fermi-LAT flux from 1 to 100 GeV during the VERITAS detection is , which is an order of magnitude larger than the four-year-averaged flux in the same energy range reported in the 3FGL catalog, (). The detection with …