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The Star Newsletter
THE HOT STAR NEWSLETTER ? An electronic publication dedicated to A, B, O, Of, LBV and Wolf-Rayet stars and related phenomena in galaxies ? No. 70 2002 July-August http://www.astro.ugto.mx/∼eenens/hot/ editor: Philippe Eenens http://www.star.ucl.ac.uk/∼hsn/index.html [email protected] ftp://saturn.sron.nl/pub/karelh/uploads/wrbib/ Contents of this newsletter Call for Data . 1 Abstracts of 12 accepted papers . 2 Abstracts of 2 submitted papers . 10 Abstracts of 6 proceedings papers . 11 Jobs .......................................................................13 Meetings ...................................................................14 Call for Data The multiplicity of 9 Sgr G. Rauw and H. Sana Institut d’Astrophysique, Universit´ede Li`ege,All´eedu 6 Aoˆut, BˆatB5c, B-4000 Li`ege(Sart Tilman), Belgium e-mail: [email protected], [email protected] The non-thermal radio emission observed for a number of O and WR stars implies the presence of a small population of relativistic electrons in the winds of these objects. Electrons could be accelerated to relativistic velocities either in the shock region of a colliding wind binary (Eichler & Usov 1993, ApJ 402, 271) or in the shocks due to intrinsic wind instabilities of a single star (Chen & White 1994, Ap&SS 221, 259). Dougherty & Williams (2000, MNRAS 319, 1005) pointed out that 7 out of 9 WR stars with non-thermal radio emission are in fact binary systems. This result clearly supports the colliding wind scenario. In the present issue of the Hot Star Newsletter, we announce the results of a multi-wavelength campaign on the O4 V star 9 Sgr (= HD 164794; see the abstract by Rauw et al.). -
Wolf-Rayet Stars in the Small Magellanic Cloud As Testbed for Massive Star Evolution A
Astronomy & Astrophysics manuscript no. smc˙wr c ESO 2018 February 8, 2018 Wolf-Rayet stars in the Small Magellanic Cloud as testbed for massive star evolution A. Schootemeijer and N. Langer Argelander-Institut¨ fur¨ Astronomie, Universitat¨ Bonn, Auf dem Hugel¨ 71, 53121 Bonn, Germany e-mail: [email protected] Received September 5, 2017; accepted December 5, 2017 ABSTRACT Context. The majority of the Wolf-Rayet (WR) stars represent the stripped cores of evolved massive stars who lost most of their hydrogen envelope. Wind stripping in single stars is expected to be inefficient in producing WR stars in metal-poor environments such as the Small Magellanic Cloud (SMC). While binary interaction can also produce WR stars at low metallicity, it is puzzling that the fraction of WR binaries appears to be about 40%, independent of the metallicity. Aims. We aim to use the recently determined physical properties of the twelve known SMC WR stars to explore their possible formation channels through comparisons with stellar models. Methods. We used the MESA stellar evolution code to construct two grids of stellar models with SMC metallicity. One of these consists of models of rapidly rotating single stars, which evolve in part or completely chemically homogeneously. In a second grid, we analyzed core helium burning stellar models assuming constant hydrogen and helium gradients in their envelopes Results. We find that chemically homogeneous evolution is not able to account for the majority of the WR stars in the SMC. However, in particular the apparently single WR star SMC AB12, and the double WR system SMC AB5 (HD 5980) appear consistent with this channel. -
ULLYSES) High-Mass and Low-Mass, Young Stars
REPORT of the HUBBLE SPACE TELESCOPE ULTRAVIOLET LEGACY SCIENCE DEFINITION WORKING GROUP Sally Oey, University of Michigan (Chair) Nate Bastian, Liverpool John Moores University Nuria Calvet, University of Michigan Paul Crowther, University of Sheffield Andrew Fox, Space Telescope Science Institute Jay Gallagher, University of Wisconsin, Ana I. Gómez de Castro, Universidad Complutense de Madrid Gregory Herczeg, Peking University Claus Leitherer, Space Telescope Science Institute Christy Tremonti, University of Wisconsin Neill Reid, Space Telescope Science Institute (ex officio) Tom Brown, Space Telescope Science Institute (ex officio) 1 EXECUTIVE SUMMARY Star formation is the basis for understanding cosmic origins from the largest scales to the smallest. High-mass stars are the tracers of star formation on extragalactic and galactic scales, and are the powerhouses of radiative, mechanical, and nucleosynthetic feedback, thus playing an essential role in galaxy evolution across cosmic time. Low-mass stars are the vast majority of stellar mass in the universe and are home to planetary systems, including the only one we know in detail: our own. At ages < 10 Myr, both high-mass and low-mass stars generate complex UV emission processes that are difficult to model, and these are central to a wide range of vital astrophysical problems, ranging from cosmic reionization to the origin of our Earth. Therefore, in response to the STScI Director’s charge to identify a large, legacy UV program focused on star formation and related stellar physics, the HST UV Legacy Science Definition Working Group recommends that the HST UV Initiative be devoted to obtaining a Hubble UV Legacy Library of to serve as a UV spectroscopic reference sample of Young Stars as Essential Standards (ULLYSES) high-mass and low-mass, young stars. -
Formation of the SMC WO+O Binary AB8
High-mass X-ray Binaries: Illuminating the Passage from Massive Binaries to Merging Compact Objects Proceedings IAU Symposium No. 346, 2019 c International Astronomical Union 2019 L.M.Oskinova,E.Bozzo,T.Bulik&D.Gies,eds. doi:10.1017/S1743921318008128 Formation of the SMC WO+O binary AB8 Chen Wang1, Norbert Langer1,G¨otz Gr¨afener1 and Pablo Marchant2 1Argelander-Institut fur Astronomie, Universit¨at Bonn, Auf dem H¨ugel 71, 53121 Bonn, Germany email: [email protected] 2Dept. of Physics & Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA Abstract. Wolf-Rayet (WR) stars are stripped stellar cores that form through strong stellar wind or binary mass transfer. It is proposed that binary evolution plays a vital role in the formation of WR stars in low metallicity environments due to the metallicity dependance of stellar winds. However observations indicate a similar binary fraction of WR stars in the Small Magellanic Cloud (SMC) compared to the Milky Way. There are twelve WR stars in the SMC and five of them are members of binary systems. One of them (SMC AB8) harbors a WO type star. In this work we explore possible formation channels of this binary. We use the MESA code to compute large grids of binary evolution models, and then use least square fitting to compare our models with the observations. In order to reproduce the key properties of SMC AB8, we require efficient semiconvection to produce a sufficiently large convective core, as well as a longer He-burning lifetime. We also need a high mass loss rate during the WN stage to assist the removal of the outer envelope. -
University Microfilms International
INFORMATION TO USERS This was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help you understand markings or notations which may appear on this reproduction. 1. The sign or “target” for pages apparently lacking from the document photographed is “Missing Page(s)”. If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure you of complete continuity. 2. When an image on the film is obliterated with a round black mark it is an indication that the film inspector noticed either blurred copy because of movement during exposure, or duplicate copy. Unless we meant to delete copyrighted materials that should not have been filmed, you will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photo graphed the photographer has followed a definite method in “sectioning” the material. It is customary to begin filming at the upper left hand corner of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again—beginning below the first row and continuing on until complete. 4. For any illustrations that cannot be reproduced satisfactorily by xerography, photographic prints can be purchased at additional cost and tipped into your xerographic copy. -
R-1237 CU-403 Nevis-297
R-1237 CU-403 Nevis-297 ColuInbia University Department of Physics New York, New York 10027 MEASUREMENTS OF R10ng AND IVcs I FROM THE CCFR EXPERIMENT Cynthia Kay McNulty Reproduction in whole or in part is permitted for any purpose by the United States Government. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Gradauate School of Arts and Sciences COLUMBIA UNIVERSITY National Science Foundation NSF PHY 95-12810 1997 - - - - - ... - ... - - - - - .... - MEASUREMENTS OF Rlong AND IVes I FROM THE CCFR EXPERIMENT Cynthia Kay McNulty Columbia University, New York, NY * Research supported by the National Science Foundation. t Submitted in partial fulfillment of the requirement for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences, ColuITlbia University. - Abstract v v The four structure functions F2 , R long' xF3 ' and xF3 are extracted from measurements of inclusive charged-current v-Fe interactions in the CCFR detector at the Fermilab Tevatron. The analysis produces measurements of ~:~~ the CKM matrix element IVes I = 1.05 ± 0.1 0 and measurements of 2 2 ~ ~ ~ ~ R long made at 0.0 x 0.425 and 1 Q 100 GeV . The new R long measurements probe a low-x kinematic region (x = 0.01) which is important for constraining the gluon distribution. - - - - - - - - Table of Contents Table of Contents i List of Figures ' iv List of Tables vi 1 Introduction 1 1.1 The Standard Model 3 1.2 Neutrino-Nucleon Scattering 8 1.3 Kinematics of a Charged-Current n Event. 10 1.4 The Formalism of Deep-Inelastic Scattering 13 - 1.5 The Parton Model 17 1.6 The Strange Sea 24 - 1.7 QCD 25 1.8 The Structure Function RZong •.••..••.....•...••.•.•••.•.•...•.......••.••.......••..•.....•...27 1.9 Analysis Overview 31 2 The Neutrino Beam and Detector 34 2.1 Neutrinos at the Fermilab Tevatron 35 2.2 Neutrino Beam 40 2.3 Detector 42 2.3.1 Target Calorimeter 43 2.3.1.1 Scintillator Counters 44 2.3.1.2 Drift Chambers 48 2.3.2 Muon Spectrometer 51 2.4 Data Acquisition 54 2.4.1 The Trigger System 55 -. -
Testing Massive Star Evolution, Star Formation History, and Feedback at Low Metallicity Spectroscopic Analysis of OB Stars in the SMC Wing?,??
A&A 625, A104 (2019) Astronomy https://doi.org/10.1051/0004-6361/201935365 & c ESO 2019 Astrophysics Testing massive star evolution, star formation history, and feedback at low metallicity Spectroscopic analysis of OB stars in the SMC Wing?,?? V. Ramachandran1, W.-R. Hamann1, L. M. Oskinova1,2, J. S. Gallagher3, R. Hainich1, T. Shenar4, A. A. C. Sander5, H. Todt1, and L. Fulmer6,7 1 Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany e-mail: [email protected] 2 Kazan Federal University, Kremlevskaya Ul. 18, Kazan, Russia 3 Department of Astronomy, University of Wisconsin, Madison, WI, USA 4 Institute of Astrophysics, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium 5 Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK 6 National Optical Astronomy Observatory, 950 North Cherry Ave., Tucson, AZ 85719, USA 7 University of Washington, Physics-Astronomy Bldg. 3910 15th Ave NE Rm. C319, Seattle, WA 98195, USA Received 20 February 2019 / Accepted 4 April 2019 ABSTRACT Stars that start their lives with spectral types O and early B are the progenitors of core-collapse supernovae, long gamma-ray bursts, neutron stars, and black holes. These massive stars are the primary sources of stellar feedback in star-forming galaxies. At low metallicities, the properties of massive stars and their evolution are not yet fully explored. Here we report a spectroscopic study of 320 massive stars of spectral types O (23 stars) and B (297 stars) in the Wing of the Small Magellanic Cloud (SMC). The spectra, which we obtained with the ESO Very Large Telescope, were analyzed using state-of-the-art stellar atmosphere models, and the stellar parameters were determined. -
Nqineering Aeru
--- Aeronautical NA,3Ar S?-/bJ\r '(;.)3, Engineering February 1988 A Continuing Bibliography with Indexes National Aeronacrtics and Space Administration Aeronautical Engineering Aem :iMg Aeronautical Engin ngirieeiring Aeronautical E %Ia IEncjineering Aevonauti n(i5Uticikl Engineering Aeronaut Aeronautical Engineering Aero 3nrhg A,eronautical EngineeringI nqineering!I Aeronautical Engine -a1w4 Enqineering Aeronautical Ei niautid Engineering Aeronaut! Pleronautical Enaineerinu- Aeru NASA SP-7037(223) AERONAUTICAL ENGINEERING A CONTINUING BIBLIOGRAPHY WITH INDEXES (Supplement 223) A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in January 1988 in Scientific and Technical Aerospace Reports (S JAR) lnternational Aerospace Abstracts (IAA). Scientific and Technical Information Division 1988 National Aeronautics and Space Administration Washington, DC This supplement is available from the National Technical Information Service (NTIS), Springfield, Virginia 22161, price code A07. INTRODUCTION This issue of Aeronautical Engineering -- A Continuing Bibliography (NASA SP-7037)lists 423 reports, journal articles and other documents originally announced in January 1988 in Scientific and Technical Aerospace Reports (STAR) or in International Aerospace Abstracts (lAA). The coverage includes documents on the engineering and theoretical aspects of design, construc- tion, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and as- sociated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles. Each entry in the bibliography consists of a standard bibliographic citation accompanied in most cases by an abstract. The listing of the entries is arranged by the first nine STAR specific categories and the remaining STAR major categories. -
Wind Properties of Wolf-Rayet Stars at Low Metallicity: Sk41 (SMC)
A&A manuscript no. ASTRONOMY (will be inserted by hand later) AND Your thesaurus codes are: 08.23.2; 08:06.3; 08.09.2 (Sk41); 11.13.1; 11.19.3 ASTROPHYSICS Wind properties of Wolf-Rayet stars at low metallicity: Sk41 (SMC) ⋆ Paul A. Crowther Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, U.K. received 4 November 1999; accepted ??? Abstract. The stellar properties of Sk 41 (AB4, WN5h), Table 1. Revised catalogue of SMC WR stars, updated the only known single Wolf-Rayet star in the SMC, are de- from Azzopardi & Breysacher (AB, 1979) to include rived from ultraviolet (IUE), optical (AAT) and near-IR MDV1 (Morgan et al. 1991) and exclude the O3If/WN6 (NTT) spectroscopy. Contrary to expectations, the stel- star AB2 (AzV39a, Walborn 1977). Spectral types follow lar properties of Sk 41 are typical of equivalent WN stars Smith et al. (1996) for WN stars or Crowther et al. (1998) in the Galaxy and LMC, with T∗ 42kK, log(L/L⊙)=5.7, for the WO star. A foreground extinction of EB−V=0.03 −1 −∼5 −1 v∞=1300 kms , M/˙ √f=3 10 M⊙yr , and H/He 2 mag is adopted, together with the SMC extinction law of by number, where f is the volume× filling factor. The stel-∼ Bouchet et al. (1985). lar luminosity of Sk 41 is 50% below the minimum value predicted by single star evolutionary models at the metal- licity of the SMC. Name AB SkAzV SpType mv EB−V Mv Mv Emission line luminosities of He ii λ4686 and C iv sys mag sys WR λλ5801-12 in SMC WR stars are not systematically lower 1 2a WN3+O4 15.2 0.26 -4.6 -3.6 than their Galactic and LMC counterparts.