Stars, Interstellar Medium and the Galaxy Commons^™

Faraday Rotation Effects For Diagnosing Magnetism In Bubble Environments., Richard Ignace

Richard Ignace

Faraday rotation is a process by which the position angle (PA) of background linearly polarized light is rotated when passing through an ionized and magnetized medium. The effect is sensitive to the line-of-sight magnetic field in conjunction with the electron density. This contribution highlights diagnostic possibilities of inferring the magnetic field (or absence thereof) in and around wind-blown bubbles from the Faraday effect. Three cases are described as illustrations: a stellar toroidal magnetic field, a shocked interstellar magnetic field, and an interstellar magnetic field within an ionized bubble.

Absolute Properties Of The Eclipsing Binary Star Ap Andromedae, Claud H. Sandberg Lacy, Guillermo Torres, Francis C. Fekel, Matthew W. Muterspaugh

Information Systems and Engineering Management Research Publications

AP And is a well-detached F5 eclipsing binary star for which only a very limited amount of information was available before this publication. We have obtained very extensive measurements of the light curve (19,097 differential V magnitude observations) and a radial velocity curve (83 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.277 ± 0.004 and 1.251 ± 0.004 M☉, radii of 1.233 ± 0.006 and 1.1953 ± 0.005 R☉, and temperatures of 6565 ± 150 K and 6495 ± 150 K. The distance to the system is …

Continuum Polarization In Circumstellar Media, Richard Ignace

ETSU Faculty Works

See http://www.asu.cas.cz/~wg2prague/

The White Dwarfs Within 25 Pc Of The Sun: Kinematics And Spectroscopic Subtypes, Edward M. Sion, J. B. Holberg, Terry D. Oswalt, George P. Mccook, Richard Wasatonic, Janine Myszka

Publications

We present the fractional distribution of spectroscopic subtypes, range and distribution of surface temperatures, and kinematical properties of the white dwarfs (WDs) within 25 pc of the Sun. There is no convincing evidence of halo WDs in the total 25 pc sample of 224 WDs. There is also little to suggest the presence of genuine thick disk subcomponent members within 25 pc. It appears that the entire 25 pc sample likely belongs to the thin disk. We also find no significant kinematic differences with respect to spectroscopic subtypes. The total DA to non-DA ratio of the 25 pc sample is …

Where Did The First Generation Of Stars Form In The Universe, Long Yan Yung, Aparna Venkatesan

Creative Activity and Research Day - CARD

The first generation of stars in the universe are expected to contain no heavy elements beyond helium, and are considered “metal-free” Population III stars (or Pop III). These metal-free stars in the early universe are predicted to have hard ionizing photon spectra and unique element yields from their supernovae, leaving signatures through the reionization of the intergalactic medium and the metal enrichment of gas in the early universe. Here, we examine the metal abundances in a variety of systems in the nearby universe, from very metal-poor Galactic halo stars to ultra-faint dwarf spheroidal galaxies, and compare them with the latest …

The Link Between Shocks, Turbulence And Magnetic Reconnection In Collisionless Plasmas, H. Karimabadi, V. Roytershteyn, H. X. Vu, Y. Omelchenko, J. Scudder, W. Daughton, A. Dimmock, Katariina (Heidi) Nykyri, Et Al.

Publications

Global hybrid (electron fluid, kinetic ions) and fully kinetic simulations of the magnetosphere have been used to show surprising interconnection between shocks, turbulence and magnetic reconnection. In particular collisionless shocks with their reflected ions that can get upstream before retransmission can generate previously unforeseen phenomena in the post shocked flows: (i) formation of reconnecting current sheets and magnetic islands with sizes up to tens of ion inertial length. (ii) Generation of large scale low frequency electromagnetic waves that are compressed and amplified as they cross the shock. These 'wavefronts' maintain their integrity for tens of ion cyclotron times but eventually …

Characterizing The Quiescent X-Ray Variability Of The Black Hole Low-Mass X-Ray Binary V404 Cyg, F Bernardini, E. M. Cackett

Physics and Astronomy Faculty Research Publications

We conducted the first long-term (75 d) X-ray monitoring of the black hole low-mass X-ray binary V404 Cyg, with the goal of understanding and characterizing its variability during quiescence. The X-ray light curve of V404 Cyg shows several flares on time-scales of hours with a count rate change of a factor of about 5–8. The root-mean-square variability isF_var = 57.0 ± 3.2 per cent. The first-order structure function is consistent with both a power spectrum of index −1 (flicker noise), or with a power spectrum of index 0 (white noise), implying that the light curve is variable on …

A Chandra Grating Observation Of The Dusty Wolf-Rayet Star Wr 48a, Svetozar A. Zhekov, Marc Gagne, Stephen L. Skinner

Earth & Space Sciences Faculty Publications

No abstract provided.

Dipole Bound Excited States Of Polycyclic Aromatic Hydrocarbons Containing Nitrogen And Their Relation To The Interstellar Medium, Mallory L. Theis

Honors College Theses

Polycyclic aromatic hydrocarbons (PAHs) are the most abundant type of molecule present in the interstellar medium (ISM). It has been hypothesized that nitrogen replacement within a ring is likely for PAHs present in the ISM. Additionally, electrons, protons, and hydrogen atoms are readily added to or removed from PAHs creating a truly diverse set of chemistries in various interstellar regions. The presence of a nitrogen within a PAH (called a PANH herein) that is additionally dehydrogenated leads to a neutral radical with a large dipole moment. It has recently been shown through the use of high-level quantum chemical computations for …

Disk-Outflow Models As Applied To High Mass Star Forming Regions Through Methanol And Water Maser Observations, Hontas Farmer

Hontas F Farmer

As the recent publication by Breen et al (2013) found Class II methanol masers are exclusively associated with high mass star forming regions. Based on the positions of the Class I and II methanol and H2O masers, UC H~II regions and 4.5~μm infrared sources, and the center velocities (vLSR) of the Class I methanol and H2O masers, compared to the vLSR of the Class II methanol masers, we propose three disk-outflow models that may be traced by methanol masers. In all three models, we have located the Class II methanol maser near the protostar, and the Class I methanol maser …

1207-3900_Nir_Spex, Jonathan Gagné

Publications and Research

No abstract provided.

The Physics Of A Space Elevator, Trevor Hamer

Thinking Matters Symposium Archive

A space elevator is a hypothetical device consisting of a long cable attached to the surface of the earth that extends upward into space. Its purpose is to provide a tether on which a vehicle could be lifted up into orbit, greatly reducing the cost of space travel. This project explains the physical forces acting on the elevator along with the kinds of materials required to keep such a cable intact. It also examines different design aspects, as well as potential problems facing the construction and usage of the elevator, and whether or not it is something we should expect …

Transit Timing Analysis In The Hat-P-32 System, M. Seeliger, D. P. Dimitrov, D. Kjurkchieva, M. Mallonn, M. Fernandez, M. Kitze, V. Casanova, G. Maciejewski, J. M. Ohlert, J. G. Schmidt, A. Pannicke, D. Puchalski, E. Gogus, T. Guver, S. Bilir, T. Ak, M. M. Hohle, T. O.B. Schmidt, R. Errmann, E.L.N. Jensen, D. H. Cohen, Laurence A. Marschall, G. Saral, I. Bernt, E. Derman, C. Galan, R. Neuhauser

Physics and Astronomy Faculty Publications

We present the results of 45 transit observations obtained for the transiting exoplanet HATP- 32b. The transits have been observed using several telescopes mainly throughout the YETI (Young Exoplanet Transit Initiative) network. In 25 cases, complete transit light curves with a timing precision better than 1.4 min have been obtained. These light curves have been used to refine the system properties, namely inclination i, planet-to-star radius ratio Rp/Rs, and the ratio between the semimajor axis and the stellar radius a/Rs. First analyses by Hartman et al. suggests the existence of a second planet in the system, thus we tried to …

Book Review: Cosmic Dawn: The Search For The First Stars And Galaxies, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Cosmic Dawn : the Search for the First Stars and Galaxies by George Rhee, springer, 2013. 279p, 9781461478126 $39.99, 9781461478133 $29.99.

1207-3900_Opt_Mage, Jonathan Gagné

Publications and Research

No abstract provided.

Deep Broadband Observations Of The Distant Gamma-Ray Blazar Pks 1424+240, P. T. Reynolds, Et Al

Physical Sciences Publications

We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z ≥ 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 ± 0.3) × 10–7 photons m–2 …

Multi-Wavelength Coverage Of State Transitions In The New Black Hole X-Ray Binary Swift J1910.2-0546, N. Degenaar, D. Maitra, E. M. Cackett, M. T. Reynolds, J M. Miller, R. C. Reis, A L. King, K. Gültekin, C D. Bailyn, M M. Buxton, R K. D Macdonald, A. C. Fabian, D B. Fox, E. S. Rykoff

Physics and Astronomy Faculty Research Publications

Understanding howblack holes accrete and supply feedback to their environment is one of the outstanding challenges of modern astrophysics. Swift J1910.2–0546 is a candidate black hole low-mass X-ray binary that was discovered in 2012 when it entered an accretion outburst. To investigate the binary configuration and the accretion morphology, we monitored the evolution of the outburst for ≃3 months at X-ray, UV, optical (B,V,R,I), and near-infrared (J,H,K) wavelengths using Swift and SMARTS. The source evolved from a hard to a soft X-ray spectral state with a relatively cold accretion disk that peaked at ≃0.5 keV. A Chandra/HETG spectrum obtained during …

The Acs Survey Of Globular Clusters. Xiii. Photometric Calibration In Comparison With Stetson Standards, Maren Hempel, Ata Sarajedini, Jay Anderson, Antonio Aparicio, Luigi R. Bedin, Brian Chaboyer

Dartmouth Scholarship

In this study we compare the photometric data of 34 Milky Way globular clusters, observed within the Advanced Camera for Surveys (ACS) Treasury Program (PI: A. Sarajedini) with the corresponding ground-based data, provided by the Photometric Standard Field Catalogs of Stetson. We focus on the transformation between the Hubble Space Telescope/ACS F606W to V-band and F814W to I-band only. The goal is to assess the validity of the filter transformation equations by Sirianni et al. with respect to their dependence on metallicity, horizontal branch morphology, mass, and integrated (V – I) color of the various …

Convection, Granulation, And Period Jitter In Classical Cepheids., Hilding Neilson, Richard Ignace

ETSU Faculty Works

Analyses of recent observations of the sole classical Cepheid in the Kepler field, V1154 Cygni, found random changes of about 30 min in the pulsation period. These period changes challenge standard theories of pulsation and evolution because the period change is non-secular, and explaining this period jitter is necessary for understanding stellar evolution and the role of Cepheids as precise standard candles. We suggest that convection and convective hot spots can explain the observed period jitter. Convective hot spots alter the timing of flux maximum and minimum in the Cepheid light curve, hence change the measured pulsation period. We present …

Convection, Granulation, And Period Jitter In Classical Cepheids., Hilding R. Neilson, Richard Ignace

Richard Ignace

Analyses of recent observations of the sole classical Cepheid in the Kepler field, V1154 Cygni, found random changes of about 30 min in the pulsation period. These period changes challenge standard theories of pulsation and evolution because the period change is non-secular, and explaining this period jitter is necessary for understanding stellar evolution and the role of Cepheids as precise standard candles. We suggest that convection and convective hot spots can explain the observed period jitter. Convective hot spots alter the timing of flux maximum and minimum in the Cepheid light curve, hence change the measured pulsation period. We present …

Star Formation And Substructure In Galaxy Clusters, Seth A. Cohen, Ryan C. Hickox, Gary A. Wegner, Maret Einasto, Jaan Vennik

Dartmouth Scholarship

We investigate the relationship between star formation (SF) and substructure in a sample of 107 nearby galaxy clusters using data from the Sloan Digital Sky Survey (SDSS). Several past studies of individual galaxy clusters have suggested that cluster mergers enhance cluster SF, while others find no such relationship. The SF fraction in multi-component clusters (0.228 +/- 0.007) is higher than that in single-component clusters (0.175 +/- 0.016) for galaxies with M^0.1_r < -20.5. In both single- and multi-component clusters, the fraction of star-forming galaxies increases with clustercentric distance and decreases with local galaxy number density, and multi-component clusters show a higher SF fraction than single-component clusters at almost all clustercentric distances and local densities. Comparing the SF fraction in individual clusters to several statistical measures of substructure, we find weak, but in most cases significant at greater than 2 sigma, correlations between substructure and SF fraction. These results could indicate that cluster mergers may cause weak but significant SF enhancement in clusters, or unrelaxed clusters exhibit slightly stronger SF due to their less evolved states relative to relaxed clusters.

Secular Damping Of Stellar Bars In Spinning Dark Matter Halos, Stacy Long, Isaac Shlosman, Clayton Heller

Department of Physics and Astronomy Faculty Publications

We demonstrate using numerical simulations of isolated galaxies that growth of stellar bars in spinning dark matter halos is heavily suppressed in the secular phase of evolution. In a representative set of models, we show that for values of the cosmological spin parameter λ ≳ 0.03, bar growth (in strength and size) becomes increasingly quenched. Furthermore, the slowdown of the bar pattern speed weakens considerably with increasing λ until it ceases completely. The terminal structure of the bars is affected as well, including extent and shape of their boxy/peanut bulges. The essence of this effect lies in the modified angular …

Spot Activity Of The Rs Canum Venaticorum Star Σ Geminorum, Perttu Kajatkari, Thomas Hackman, Lauri Jetsu, Jyri J. Lehtinen, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Aims. We model the photometry of RS CVn star σ Geminorum to obtain new information on the changes of the surface starspot distribution, that is, activity cycles, differential rotation, and active longitudes.

Methods. We used the previously published continuous period search (CPS) method to analyse V-band differential photometry obtained between the years 1987 and 2010 with the T3 0.4 m Automated Telescope at the Fairborn Observatory. The CPS method divides data into short subsets and then models the light-curves with Fourier-models of variable orders and provides estimates of the mean magnitude, amplitude, period, and light-curve minima. These light-curve parameters …

Interaction Between The Broad-Lined Type Ic Supernova 2012ap And Carriers Of Diffuse Interstellar Bands, Dan Milisavljevic, Raffaella Margutti, Kyle N. Crabtree, Jonathan B. Foster, Alicia M. Soderberg, Robert A. Fesen, Jerod T. Parrent

Dartmouth Scholarship

Diffuse interstellar bands (DIBs) are absorption features observed in optical and near-infrared spectra that are thought to be associated with carbon-rich polyatomic molecules in interstellar gas. However, because the central wavelengths of these bands do not correspond to electronic transitions of any known atomic or molecular species, their nature has remained uncertain since their discovery almost a century ago. Here we report on unusually strong DIBs in optical spectra of the broad-lined Type Ic supernova SN 2012ap that exhibit changes in equivalent width over short ( 30 days) timescales. The 4428 Å and 6283 Å DIB features get weaker with …

The Orbits Of The Triple-Star System 1 Geminorum From Phases Differential Astrometry And Spectroscopy, Benjamin F. Lane, Matthew W. Muterspaugh, Roger F. Griffin, Colin D. Scarfe, Francis C. Fekel, Michael H. Williamson, Joel A. Eaton, Michael Shao, Mark M. Colavita, Maciej Konacki

Information Systems and Engineering Management Research Publications

We have used precise differential astrometry from the Palomar High-precision Astrometric Search for Exoplanet Systems project and radial-velocity measurements covering a time span of 40 yr to determine the orbital parameters of the 1 Geminorum triple system. We present the first detection of the spectral lines of the third component of the system, together with precise mass (0.5%) and distance (0.15%) determinations for this system. In addition, our astrometry allows us to make the first determination of the mutual inclination of the orbits.

Evidence For A Weak Wind From The Young Sun, Brian E. Wood, Hans-Reinhard Müller, Seth Redfield, Eric Edelman

Dartmouth Scholarship

The early history of the solar wind has remained largely a mystery due to the difficulty of detecting winds around young stars that can serve as analogs for the young Sun. Here we report on the detection of a wind from the 500 Myr old solar analog π1 UMa (G1.5 V), using spectroscopic observations from the Hubble Space Telescope. We detect H I Lyα absorption from the interaction region between the stellar wind and interstellar medium, i.e., the stellar astrosphere. With the assistance of hydrodynamic models of the π1 UMa astrosphere, we infer a wind only half as strong as …

Extensive Study Of Hd 25558, A Long-Period Double-Lined Binary With Two Spb Components, Á. Sódor, Peter De Cat, David J. Wright, Coralie Neiner, Maryline Briquet, Patricia Lampens, Robert J. Dukes, Gregory W. Henry, Michael H. Williamson, Emily Brunsden, Karen R. Pollard, Peter L. Cottrell, Florian Maisonneuve, Pam M. Kilmartin, Jaymie Matthews, Thomas Kallinger, Paul G. Beck, Eiji Kambe, Chris A. Engelbrecht, Robert J. Czanik, Stephenson Yang, Osamu Hashimoto, Satoshi Honda, Jian-Ning Fu, Barbara Castanheira, Holger Lehmann, Zsófia Bognár, Natalie Behara, Simone Scaringi, Hans Van Winckel, Jonathan Menu, Alex Lobel, P. Mathias, Sophie Saesen, Maja Vučković, The Mimes Collaboration

Information Systems and Engineering Management Research Publications

We carried out an extensive observational study of the Slowly Pulsating B (SPB) star, HD 25558. The ≈2000 spectra obtained at different observatories, the ground-based and MOST satellite light curves revealed that this object is a double-lined spectroscopic binary with an orbital period of about nine years. The observations do not allow the inference of an orbital solution. We determined the physical parameters of the components, and found that both lie within the SPB instability strip. Accordingly, both show line-profile variations due to stellar pulsations. 11 independent frequencies were identified in the data. All the frequencies were attributed to one …

Black Hole Variability And The Star Formation-Active Galactic Nucleus Connection: Do All Star-Forming Galaxies Host An Active Galactic Nucleus?, Ryan C. Hickox, James R. Mullaney, David M. Alexander, Chien-Ting J. Chen, Francesca M. Civano, Andy D. Goulding, Kevin N. Hainline

Dartmouth Scholarship

We investigate the effect of active galactic nucleus (AGN) variability on the observed connection between star formation and black hole accretion in extragalactic surveys. Recent studies have reported relatively weak correlations between observed AGN luminosities and the properties of AGN hosts, which has been interpreted to imply that there is no direct connection between AGN activity and star formation. However, AGNs may be expected to vary significantly on a wide range of timescales (from hours to Myr) that are far shorter than the typical timescale for star formation (100 Myr). This variability can have important consequences for observed correlations. We …

The Structure Of Broad Line Region And The Effects Of Cooling Function In Active Galactic Nuclei, Ye Wang

Theses and Dissertations--Physics and Astronomy

Active Galactic Nuclei (AGNs) are the most mystic objects in the universe. They are usually very far away from our Galaxy, which means that they are ancient objects. They are also luminous and have unique features in their spectra. Studying AGNs helps understanding the early universe and the evolution of galaxies. This Dissertation aims to research the structure of AGNs and the cooling function in the AGNs environment.

I first investigate what optical/ultraviolet spectroscopic features would be produced by Broad-line Region (BLR) clouds crossing our line of sight to the accretion disk, the source of the optical/UV continuum. This research, …

Orion, Katelyn G. Gyorkos

Natural Sciences Student Research Presentations

The purpose of this project was to gather information about the stars and objects in the constellation Orion. This is a project for the Natural Sciences Poster Session at Parkland College.