DOCSLIB.ORG

A Fine Analysis of the Helium-Rich Star Hd184927. Norman Arthur Higginbotham Louisiana State University and Agricultural & Mechanical College

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Fine Analysis of the Helium-Rich Star Hd184927. Norman Arthur Higginbotham Louisiana State University and Agricultural & Mechanical College Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1974 A Fine Analysis of the Helium-Rich Star Hd184927. Norman Arthur Higginbotham Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Higginbotham, Norman Arthur, "A Fine Analysis of the Helium-Rich Star Hd184927." (1974). LSU Historical Dissertations and Theses. 2671. https://digitalcommons.lsu.edu/gradschool_disstheses/2671 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. 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 original submitted. The following explanation of techniques is provided to help you understand markings or patterns 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 thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the fiim is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 75-1932 HIGGINBOTHAM, Noman A rth u r, 1943- A FINE ANALYSIS OF THE HELIUM-RICH STAR HD 184927. The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1974 Astronomy Xerox University Microfilms, Ann Arbor, Michigan 48106 THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. A FINE ANALYSIS OF THE. HELIUM—RICH STAR HD 184927 A DISSERTATION Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Physics and Astronomy by Norman Arthur Higginbotham B.S., Louisiana State University, 1970 M.S., Louisiana State University, 1972 August, 1974 ACKNOWLEDGMENTS I would like to express my deepest appreciation and gratitude to my wife, Lucille. Without her continual encouragement and patient endurance, her lasting love and devotion to a husband and his dream, and, lastly, her much needed editing and typing abilities, this dissertation could not have been written. Never have I known an individual who could give so much while asking for so little; let this be a declaration of my appreciation of a long forbearance. I also extend my deepest thanks to Dr. Paul D. Lee, my thesis advisor, for his interest and guidance in this research. This work was initiated at his suggestion and to him I am most indebted for invaluable teaching, assistance, and friendship throughout my graduate school experience. His influence has affected all aspects of my graduate education; being his student has been a pleasant and rewarding experience. Dr. D. M. Peterson kindly made available extensive amounts of his data in advance of publication, for which I am grateful. To Martha Prather who, upon very short notice, typed the final manuscript, I extend my sincere appreciation. And, finally, I thank my two precious children, Normandy and Gus, who somehow have made this endeavor ii completely worthwhile. I gratefully acknowledge the Dr. Charles E. Coates Memorial Fund, donated by George H. Coates, for financial assistance pertinent to the publication of this disserta­ tion. TABLE OF CONTENTS Page I. Introduction 1 A. Spectral Classification 1 B. A "Normal" Stellar Helium to Hydrogen Ratio 10 C. Early-type Stellar Objects Having Abnormal Helium Abundances 12 1. Subdwarf B Stars 12 2. Helium-weak Stars 13 3. Subdwarf O Stars 13 4. Hydrogen-deficient, or Helium Stars 14 5. Non-classified, Helium Anomalous Stars 14 6. Helium-rich Stars 15 D. The Helium-rich Class of Stellar Objects 15 E. Known or Suspected Helium-rich Stars 16 F. HD 184927 27 II. Observations and Reduction 30 A. Photometric Observations: Wide-band 30 B. Photometric Observations: Narrow-band 30 C. The Line Spectrum 33 III. The Coarse Analysis 39 A. Effective Temperature Determination 39 iv B. The Helium to Hydrogen Ratio 43 C. Determination of Surface Gravity 52 IV. Model Stellar Atmospheres and Line Profile Calculations 54 A. Model Stellar Atmospheres - Qualitative 54 B. Model Stellar Atmospheres - Quantitative 60 C. Line Profile Calculations - General 73 D. Line Profile Calculations - Quantitative 76 V. A Fine Analysis of HD 184927 83 A. Helium-rich Model Atmosphere Grid and Line Program 83 B. Model Fitting 85 1. The Balmer and He I Lines 86 2. The Hy and HS Profiles 87 3. The Continuous Spectrum and Balmer Discontinuity 90 4. Microturbulence 92 5. Ionization Equilibria 93 6. Final Atmospheric Parameters 95 C. Metallic Line Analysis 97 D. Individual Metallic Results 99 1. Carbon, Nitrogerv and Oxygen 99 2. Silicon and Sulfur 99 3. Aluminum 100 v 4. Argon 100 5. Iron 101 6. Phosphorus, Magnesium, and Neon 102 E. Absolute Magnitude, Mass, Radius, Luminosity, and Distance 102 VI. Conclusions 106 Tables 109 Figures 140 References 152 Appendix I - A Simple Adiabatic Approach to Stark Broadening for the Hydrogen Lines 161 Appendix II - Hydrogenic Stark Broadening Based on the "Modified Impact Theory" 172 Appendix III - A Semi-Empirical Approach to Stark Broadening 176 Vita 180 TABLE CAPTIONS Table 1 Known or suspected helium-rich stars. Also listed are values of effective temperature, surface gravity and helium content as deter­ mined by references given in column 5. Table 2 Equivalent widths of several hydrogen and helium lines for representative normal, helium- rich, and helium stars. Table 3 Helium/hydrogen line ratios and helium abun­ dances for the known helium-rich stars. Table 4 Photometric observations of HD 184927. Table 5 Continuum measurements of HD 184927; observa­ tions of 4/5 April 1973. Table 6 Continuum measurements of HD 184927; observa­ tions of 23/24 April 1973. Table 7 Continuum fluxes for HD 184927. Table 8 Observational material for the analysis of HD 184927. Table 9 Calibration wavelengths of spectrograms of HD 184927. Table 10 Observed line profiles in HD 184927. Table 11 The metallic line spectrum of HD 184927. Grouped by ion, in columns one through five are listed multiplet number, wavelength in angstroms, log gf and reference, the measured equivalent vii width in milliangstroms, and determined abun­ dance. The final averaged abundance is listed to the right of the ion identification intro­ ducing each grouping. Table 12 Photometry for several helium-rich stars. Table 13 A comparison of the effective temperature scales of Morton and Adams, Hyland, and Schild, Peterson, and Oke. Table 14 A comparison of computed values of effective temperature for several helium-rich stars. Table 15 Values employed in the determination of N(HI,n=2). In columns one through five are listed the upper principal quantum number, wavelength in angstroms, measured (average) equivalent width, f-value, and the determined value of log N(HI,n=2). Table 16 Values employed in the determination of 3 N(He I, 2 P). Columns are as given in Table 15. Table 17 Extrapolated value and weight of log N(A) for helium. Table 18 Unreddened continuum fluxes for HD 184927. Table 19 Abundances (log e) in HD 184927, the Sun, and normal B stars. viii FIGURE CAPTIONS Figure 1 Measured He/H line ratios, [W^(HeIX 4143)/Wx (H6)] and [Wx (He I X 4471)/Wx (Hy)], as func­ tions of helium abundance, N(He), determined from fine analyses for the helium-rich stars, HD 144941 and BD + 13° 3224. The solid lines are representative changes as determined from the model atmospheres and lines. Figure 2 A segment of the standard color-color diagram showing the positions of four helium-rich stars, HD 184927, HD 96446, HD 37017, and HD 37479 having known UBV photometry. Posi­ tions are for unreddened values. Approximate temperatures are indicated along the standard two-color line. A representative change in colors with helium enrichment is indicated. Figure 3 log N(A) for various upper levels of hydrogen and helium. Each helium series has been re- 3 duced to the 2 P level. Figure 4a Theoretical equivalent widths for Hy as a function of log n„ for various values of li gravity and effective temperature. Figure 4b Theoretical equivalent widths for X 4471 of He I as a function of log n„; same notation h as in Figure 4a.
Load more

Recommended publications
  • Ultraviolet and Visual Flux and Line Variations of One of the Least Variable Bp Stars HD 64740
    Astronomy & Astrophysics manuscript no. hd64740 c ESO 2018 August 28, 2018 Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740⋆ J. Krtiˇcka1, J. Jan´ık1, H. Markov´a1, Z. Mikul´aˇsek1,2, J. Zverko1, M. Prv´ak1, and M. Skarka1 1 Department of Theoretical Physics and Astrophysics, Masaryk University, Kotl´aˇrsk´a2, CZ-611 37 Brno, Czech Republic 2 Observatory and Planetarium of J. Palisa, VSBˇ – Technical University, Ostrava, Czech Republic Received ABSTRACT Context. The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not. Aims. We study the Bp star HD 64740 to investigate how its remarkable inhomogeneities in the surface distribution of helium and silicon, and the corresponding strong variability of many spectral lines, can result in one of the faintest photometric variabilities among the Bp stars. Methods. We used model atmospheres and synthetic spectra calculated for the silicon and helium abundances from surface abundance maps to predict the ultraviolet and visual light and line variability of HD 64740. The predicted fluxes and line profiles were compared with the observed ones derived with the IUE, HST, and Hipparcos satellites and with spectra acquired using the FEROS spectrograph at the 2.2m MPG/ESO telescope in La Silla. Results. We are able to reproduce the observed visual light curve of HD 64740 assuming an inhomogeneous distribution of iron correlated with silicon distribution.
    [Show full text]
  • Fundamental Parameters of He-Weak and He-Strong Stars,
    Astronomy & Astrophysics manuscript no. aa6454-06 c ESO 2007 April 19, 2007 Fundamental parameters of He-weak and He-strong stars, L. S. Cidale1,M.L.Arias1, A. F. Torres1,J.Zorec2,Y.Frémat3, and A. Cruzado1 1 Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata and Instituto de Astrofísica de La Plata (CONICET), Paseo del Bosque S/N, 1900 La Plata, Buenos Aires, Argentina e-mail: [email protected] 2 Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis bd. Arago, 75014 Paris, France 3 Royal Observatory of Belgium, 3 Av. Circulaire, 1180 Bruxelles, Belgium Received 27 September 2006 / Accepted 15 March 2007 ABSTRACT Context. He-weak and He-strong stars are chemically peculiar AB objects whose He lines are anomalously weak or strong for their MK spectral type. The determination of fundamental parameters for these stars is often more complex than for normal stars due to their abundance anomalies. Aims. We discuss the determination of fundamental parameters: effective temperature, surface gravity, and visual and bolometric absolute magnitudes of He-weak and He-strong stars. We compare our values with those derived independently from methods based on photometry and model fitting. Methods. We carried out low resolution spectroscopic observations in the wavelength range 3400–4700 Å of 20 He-weak and 8 He-strong stars to determine their fundamental parameters by means of the Divan-Chalonge-Barbier (BCD) spectrophotometric system. This system is based on the measurement of the continuum energy distribution around the Balmer discontinuity (BD). For a few He-weak stars we also estimate the effective temperatures and the angular diameters by integrating absolute fluxes observed over a wide spectral range.
    [Show full text]
  • Wind Variability of B Supergiants
    (will..1,stronomyI)e inserted,(" ..Lstrophysicsby hand late[')manuscript no. Wind variability of B supergiants IV. A survey of IUE time-series data of 11 B0 to B3 stars R.K. Prinja l, I). Massa 2 and A.W. Fullerton _'4 Depaatment of Physics & Astr moray, [:niversity College London, Gower Street, London WC1E 6BT. U.N. e-mail: rkpQstar, ucl. ac. uk 2 Raytheon ITSS, NASA/GSFC (;ode681, C.reenbeh, MD 20771. USA e-mall: massaOt aot ao.,ona, gsl c. nasa. gov "_ Department of Physics and As1 ronomy, University of Victoria. P.O. Box 3055. Victoria, BC VSW .3P6, Canada e-mail: awf@pha, jhu. edu 4 Center for Astrophysical Sciences, Dept. of Physics and Astronomy. ,Johns Hopkins University,3400 N. Charles St. Baltimore, MD 21218-2686 lrSA Received : accepted Abstract. We present the most suitable data sets available in the International Ultraviolet Explorer(IUE) archive for the study of time-dependent stellar winds in early B supergiants. The UV line profile variability in 11 B0 to Ba stars is analysed, compared and discussed, based on 1B separate data sets comprising over 600 homogeneously re- duced high-resolution spectrograms. The targets include 'normal' stars with moderate rotation rates and examples of rapid rotators. A gallery of grey-scale images (dynamic spectra) is presented, which demonstrates the richness and range of wind variability and highlights different structures in the winds of these stars. This work emphasises the suitability of B supergiants _br wind studies, under-pinned by the fact that they exhibit unsaturated wind lines for a wide range of ionizaticn.
    [Show full text]
  • Fundamental Parameters of He-Weak and He-Strong Stars* **
    A&A 468, 263-272 (2007) Astronomy DOI: 10.1051/0004-6361:20066454 © ESO 2007 Astrophysics Fundamental parameters of He-weak and He-strong stars* ** L. S. Cidale1, M. L. Arias1, A. F. Torres1, J. Zorec2, Y. Frémat3. and A. Cruzado1 1 Facultad de Ciencias Astronómicas y Geofísicas. Universidad Nacional de La Plata and Instituto de Astrofísica de La Plata (CONICET), Paseo del Bosque S/N, 1900 La Plata. Buenos Aires. Argentina e-mail: lydia@fcaglp. fcaglp. unlp. edu. ar 2 Institut d’Astrophysique de Paris, UMR7095 CNRS. Université Pierre & Marie Curie. 98bis bd. Arago, 75014 Paris. France 3 Royal Observatory of Belgium. 3 Av. Circulaire. 1180 Bruxelles. Belgium Received 27 September 2006 / Accepted 15 March 2007 ABSTRACT Context. He-weak and He-strong stars are chemically peculiar AB objects whose He lines are anomalously weak or strong for their MK spectral type. The determination of fundamental parameters for these stars is often more complex than for normal stars due to their' abundance anomalies. Aims. We discuss the determination of fundamental parameters: effective temperature, surface gravity, and visual and bolometric absolute magnitudes of He-weak and He-strong stars. We compare our values with those derived independently from methods based on photometry and model fitting. Methods. We carried out low resolution spectroscopic observations in the wavelength range 340()—4700 A of 20 He-weak and 8 He-strong stars to determine their' fundamental parameters by means of the Divan-Chalonge-Barbier (BCD) spectrophotometric system. This system is based on the measurement of the continuum energy distribution around the Balmer discontinuity (BD).
    [Show full text]
  • The Magnetic Early B-Type Stars I: Magnetometry and Rotation
    Mon. Not. R. Astron. Soc. 000, 1–?? (2002) Printed 10 January 2018 (MN LATEX style file v2.2) The Magnetic Early B-type Stars I: Magnetometry and Rotation M. E. Shultz1,2,3,4⋆, G. A. Wade2, Th. Rivinius3, C. Neiner5, E. Alecian5, D. Bohlender6, D. Monin6, J. Sikora1,2 and the MiMeS and BinaMIcS Collaborations ⋆† 1Department of Physics, Engineering Physics & Astronomy, Queen’s University, Kingston, ON Canada, K7L 3N6 2Department of Physics, Royal Military College of Canada, Kingston, Ontario K7K 7B4, Canada 3ESO - European Organisation for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19, Chile 4Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 75120 5LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universits, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cit, 5 place Jules Janssen, 92195 Meudon, France 6National Research Council of Canada, Herzberg Institute of Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, ABSTRACT The rotational and magnetic properties of many magnetic hot stars are poorly char- acterized, therefore the MiMeS and BinaMIcS collaborations have collected extensive high-dispersion spectropolarimetric datasets of these targets. We present longitudinal magnetic field measurements hBzi for 52 early B-type stars (B5 to B0), with which we attempt to determine their rotational periods Prot. Supplemented with high-resolution spectroscopy, low-resolution DAO circular spectropolarimetry, and archival Hipparcos photometry, we determined Prot for 10 stars, leaving only 5 stars for which Prot could not be determined. Rotational ephemerides for 14 stars were refined via comparison of new to historical magnetic measurements. The distribution of Prot is very similar to that observed for the cooler Ap/Bp stars.
    [Show full text]
  • Evasion Maneuvers with Double Lunar Flyby for Interplanetary Missions
    POLITECNICO DI TORINO Department of Mechanical and Aerospace Engineering Master degree course in Aerospace Engineering Master Degree Thesis Evasion maneuvers with double lunar flyby for interplanetary missions Supervisor Candidate Lorenzo Casalino Sebastiano Bugno Matricola: 239257 Academic Year 2017-2018 Acknowledgements I would first like to thank my thesis advisor Professor Lorenzo Casalino of the Mechanics and Aerospace department (DIMEAS) at Politecnico of Turin. I owe him a special thanks, because he was always available for every problem or doubt about this thesis and his help it was essential for the success of the work. In addition, I must express my very profound gratitude to my family for providing me with unfailing support and continuous encouragement throughout my years of study and for the moving to Turin. This accomplishment would not have been possible without them. Thank you so much. Contents List of Figures iii List of Tables v 1 Introduction 1 2 Evasion maneuvers 3 2.1 Short background on interplanetary missions................3 2.2 Escape......................................5 2.3 Flyby......................................8 3 Approximate analytical approach 11 3.1 Introduction................................... 11 3.2 Trajectory analysis............................... 12 3.2.1 Moon to Escape............................ 13 3.2.2 Moon to Moon............................. 13 3.2.3 Perigee to Moon............................ 15 3.3 Calculations................................... 16 4 Exact numerical solution 19 4.1 Solution description.............................. 19 4.2 Equations.................................... 22 4.3 Perturbations.................................. 23 4.3.1 Earth asphericity............................ 24 4.3.2 LuniSolar perturbation......................... 24 4.3.3 Solar radiation pressure........................ 26 5 Approximate analytical approach results 27 5.1 Features..................................... 27 5.2 Case 0 (comparison between exact and approximated solution).....
    [Show full text]
  • Evidence of a Massive Black Hole Companion in the Massive
    Evidence of a Massive Black Hole Companion in the Massive Eclipsing Binary V Puppis Qian S.-B.1,2,3, Liao W.-P.1,2,3, and Fern´andez Laj´us, E.4 ABSTRACT Up to now, most stellar-mass black holes were discovered in X-ray emitting binaries, in which the black holes are formed through a common-envelope evolu- tion. Here we give evidence for the presence of a massive black hole candidate as a tertiary companion in the massive eclipsing binary V Puppis. We found that the orbital period of this short-period binary (P=1.45 days) shows a periodic variation while it undergoes a long-term increase. The cyclic period oscillation can be interpreted by the light-travel time effect via the presence of a third body with a mass no less than 10.4 solar mass. However, no spectral lines of the third body were discovered indicating that it is a massive black hole candidate. The black hole candidate may correspond to the weak X-ray source close to V Puppis discovered by Uhuru, Copernicus, and ROSAT satellites produced by accreting materials from the massive binary via stellar wind. The circumstellar matter with many heavy elements around this binary may be formed by the supernova explosion of the progenitor of the massive black hole. All of the observations suggest that a massive black hole is orbiting the massive close binary V Pup- pis with a period of 5.47 years. Meanwhile, we found the central close binary is undergoing slow mass transfer from the secondary to the primary star on a nuclear time scale of the secondary component, revealing that the system has passed through a rapid mass-transfer stage.
    [Show full text]
  • Dissertation
    DISSERTATION Titel der Dissertation “Solar-like oscillations in Delta Scuti stars” Verfasserin Mag. rer. nat. Victoria Laura Antoci angestrebter akademischer Grad Doktorin der Naturwissenschaften (Dr. rer. nat.) Wien, 2011 Studienkennzahl lt. Studienblatt: A 091 413 Dissertationsgebiet lt. Studienblatt: Astronomie Betreuer: PD Mag. Dr. Gerald Handler Contents 1 Introduction 5 1.1 Radialandnon-radialpulsations . 5 1.2 PressureandGravitymodes . 8 2 δ Scuti stars 13 2.1 Pulsationmechanisms . 13 2.2 Characterization of δ Scutistars..................... 16 2.3 Predictions of solar-like oscillations in δ Scutistars . 20 2.3.1 Solar-likeoscillationsinFstars . 23 3 Radial velocity measurements 25 3.1 Theiodinetechnique ........................... 25 3.2 iSONG................................... 28 4 The δ Sct star ρ Puppis 29 4.1 History................................... 29 4.2 Fundamentalparameters . 30 4.3 Observationsanddatareduction. 31 4.4 Photometry ................................ 35 4.4.1 MOSTdata ............................ 35 4.4.2 Ground-basedphotometry . 36 4.4.3 Interpretation and discussion . 42 4.5 RadialVelocities ............................. 45 4.5.1 GettingiSONGstarted. 45 4.5.2 Fittingtheinstrumentalprofile . 45 4.5.3 Intrinsicstellarspectrum . 46 4.5.4 Fittingtheobservations . 46 4.5.5 ESPaDONsradialvelocities . 67 4.6 Searching for solar-like oscillations . ...... 68 5 The Kepler satellite 78 5.1 NaturepublicationonHD187547 . 81 6 Conclusions & Discussion 97 7 Abstract 100 3 8 Zusammenfassung 102 Bibliography 104 9 Acknowledgements 111 10 Curriculum Vitae 112 1 Introduction The first chapter’s opening paragraph of Sir Arthur Eddington’s meanwhile leg- endary book ’The Internal Constitution of the Stars’ (1926) is the following: ’At first sight it would seem that the deep interior of the sun and stars less accessible to scientific investigation than any other region of the universe.
    [Show full text]
  • Správa O Činnosti Organizácie SAV Za Rok 2010
    Astronomický ústav SAV Správa o činnosti organizácie SAV za rok 2010 Tatranská Lomnica január 2011 Obsah osnovy Správy o činnosti organizácie SAV za rok 2010 1. Základné údaje o organizácii 2. Vedecká činnosť 3. Doktorandské ńtúdium, iná pedagogická činnosť a budovanie ľudských zdrojov pre vedu a techniku 4. Medzinárodná vedecká spolupráca 5. Vedná politika 6. Spolupráca s VŃ a inými subjektmi v oblasti vedy a techniky v SR 7. Spolupráca s aplikačnou a hospodárskou sférou 8. Aktivity pre Národnú radu SR, vládu SR, ústredné orgány ńtátnej správy SR a iné organizácie 9. Vedecko-organizačné a popularizačné aktivity 10. Činnosť kniņnično-informačného pracoviska 11. Aktivity v orgánoch SAV 12. Hospodárenie organizácie 13. Nadácie a fondy pri organizácii SAV 14. Iné významné činnosti organizácie SAV 15. Vyznamenania, ocenenia a ceny udelené pracovníkom organizácie SAV 16. Poskytovanie informácií v súlade so zákonom o slobodnom prístupe k informáciám 17. Problémy a podnety pre činnosť SAV PRÍLOHY A Zoznam zamestnancov a doktorandov organizácie k 31.12.2010 B Projekty riešené v organizácii C Publikačná činnosť organizácie D Údaje o pedagogickej činnosti organizácie E Medzinárodná mobilita organizácie Správa o činnosti organizácie SAV 1. Základné údaje o organizácii 1.1. Kontaktné údaje Názov: Astronomický ústav SAV Riaditeľ: RNDr. Aleń Kučera, CSc. Zástupca riaditeľa: doc. RNDr. Ján Svoreņ, DrSc. Vedecký tajomník: RNDr. Drahomír Chochol, DrSc. Predseda vedeckej rady: RNDr. Augustín Skopal, DrSc. Adresa: Astronomický ústav SAV, 059 60 Tatranská Lomnica http://www.ta3.sk Tel.: 052/ 7879 111 Fax: 052/ 4467 656 E-mail: [email protected] Názvy a adresy detašovaných pracovísk: Astronomický ústav - Oddelenie medziplanetárnej hmoty Dúbravská cesta 9, 845 04 Bratislava Vedúci detašovaných pracovísk: Astronomický ústav - Oddelenie medziplanetárnej hmoty Prof.
    [Show full text]
  • Subject Index
    Subject Index Absolute flux determinations AHS in Herbig-Haro objects 209 for Herbig-Haro objects 214 Angular dimensions Absolute radiation, measurements 9 of H20 sources 265 Absorption of OH sources 262,263 continuous 42 Anisotropy in masers 270,282 line 38,41 Anti-inversion 289 molecular 44 Ap phenomenon 129 Absorption coefficient 29,267 origin 132 depth dependence 27 Ap stars effecti ve 336 magnetic fields 107 for grains 242 magnetosphere 137 f. negative 257 major groups 109 f. Absorption profiles in masers 266 nuclear reactions 132 Abundance anomalies 102 separation of elements 132 Abundance gradients 102 supernova-binary hypothesis 134 Abundances surface spallation 134 definition 102 Ap-type anomalies 132 in CNO stars 119 H. detectability 117 of heavy elements 21 ff. hot boundary in Clog g, log Teff)­ in helium stars 81 plane 140 H. in Herbig-Haro objects 220 of population II B stars 129 metal 51 ATLAS, model atmosphere program 15 normal 104 Atmospheric parameters iri O-subdwarfs 83,84 of helium stars 72 in population II B stars 125 ff. A-type horizontal branch stars 149 ff. relative 103 solar 15,104 Backwarming effect 23 in weak-helium-line stars 112 f.,116 Balmer decrement in the spectrum in white dwarfs 177,182 ff. of Herbig-Haro objects 209 Accretion 139,189,192,306,315 Balmer discontinuity 34,36,37 Acoustic waves 302 in helium stars 68,73,76 Activity, stellar 305,309 in horizontal branch stars 153 358 subject Index Balmer lines 39,45,303,308 Carbon stars 57 in horizontal branch stars 153 Center to limb variation solar 13 in cosmic masers 270 Be stars 313 solar 8 Binaries 302,314 ff.
    [Show full text]
  • The Messenger
    THE MESSENGER No. 12-March 1978 La Silla Anno 19xx? The ESO Conference on Optical Telescopes of the Future (p. 2) showed a clear division be- tween the astronomers who want very large te- \ lescopes (16 to 25 m class) and those who opt for an array of interlinked "smalI" telescopes (-tOD elements, each 2-3 m mirror diameter). Confronted with the continuously increasing demand for precious telescope time on La Silla (p. 16), we here present the "optimal-solution plan" for La Silla that recent/y leaked from the ultra-secret ESO Planning Group (not even the Finance Committee knows about it!). Drawn by Karen Humby of the Engineering Group in Ge- neva, this beautifully simple conception pur­ portedly aims at the definitive pacification of the various advocates of future telescopes by a masterful combination ofsize and quantity. It is reported, however, that fears have been ex- pressed about the long-term stability of the support . .. no, you are wrong, of the La Silla bedrock, of course. ESO Conference on Optical Telescopes of the Future This conference took place in Geneva between 12 and incoherent addition of more photons from bigger systems, a 15 December 1977. strongly vocal minority was clearly convinced that tech­ The time seemed ripe for a conference on this subject, for niques using phase information should not be neglected. many ideas are in the air and certain projects in the United The discussion also inevitably brought up the vexed ques­ States which deviate markedly from the conventional tele­ tion of how an astronomer should or would like (not neces­ scope are al ready completed or in active study.
    [Show full text]
  • Ultraviolet and Visual Flux and Line Variations of One of the Least Variable Bp Stars HD 64740⋆
    A&A 556, A18 (2013) Astronomy DOI: 10.1051/0004-6361/201221018 & c ESO 2013 Astrophysics Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740 J. Krtickaˇ 1, J. Janík1, H. Marková1, Z. Mikulášek1,2,J.Zverko1,M.Prvák1, and M. Skarka1 1 Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlárskᡠ2, 61137 Brno, Czech Republic e-mail: [email protected] 2 Observatory and Planetarium of J. Palisa, VŠB − Technical University, 70833 Ostrava, Czech Republic Received 29 December 2012 / Accepted 23 May 2013 ABSTRACT Context. The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not. Aims. We study the Bp star HD 64740 to investigate how its remarkable inhomogeneities in the surface distribution of helium and silicon, and the corresponding strong variability of many spectral lines, can result in one of the faintest photometric variabilities among the Bp stars. Methods. We used model atmospheres and synthetic spectra calculated for the silicon and helium abundances from surface abundance maps to predict the ultraviolet and visual light and line variability of HD 64740. The predicted fluxes and line profiles were compared with the observed ones derived with the IUE, HST, and Hipparcos satellites and with spectra acquired using the FEROS spectrograph at the 2.2 m MPG/ESO telescope in La Silla. Results. We are able to reproduce the observed visual light curve of HD 64740 assuming an inhomogeneous distribution of iron correlated with silicon distribution.
    [Show full text]