DOCSLIB.ORG

The Atmospheric Chemistry of Magnetic Bp Stars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Atmospheric Chemistry of Magnetic Bp Stars Western University Scholarship@Western Electronic Thesis and Dissertation Repository 8-12-2013 12:00 AM The atmospheric chemistry of magnetic Bp stars Jeffrey D. Bailey The University of Western Ontario Supervisor Dr. John D. Landstreet The University of Western Ontario Graduate Program in Astronomy A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Jeffrey D. Bailey 2013 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Stars, Interstellar Medium and the Galaxy Commons Recommended Citation Bailey, Jeffrey D., "The atmospheric chemistry of magnetic Bp stars" (2013). Electronic Thesis and Dissertation Repository. 1420. https://ir.lib.uwo.ca/etd/1420 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. THE ATMOSPHERIC CHEMISTRY OF MAGNETIC BP STARS (Thesis format: Integrated Article) by Jeffrey Bailey Graduate Program in Astronomy A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy The School of Graduate and Postdoctoral Studies The University of Western Ontario London, Ontario, Canada c Jeffrey Daniel Bailey 2013 Abstract The chemically peculiar magnetic A- and B-type (Ap/Bp) stars are characterised by large overabundances, of the order of 102 and 104 times the Sun, of Fe-peak and rare earth elements, respectively. Further, they possess strong, ordered magnetic fields (of order 1 kG) that are roughly dipolar in nature. We present in-depth investigations of magnetic Ap/Bp stars, ranging from detailed analyses of specific stars to larger surveys aimed at studying stratification and atmospheric abundance evolution. For HD 133880 and HD 147010, we offer complete investigations of their magnetic fields and chemical abundance distributions. For each star, a simple magnetic field model is de- rived, from both line-of-sight and surface magnetic field measurements, that consists of dipole, quadrupole and octupole components. Abundance analysis is then performed using zeeman, a spectrum synthesis program that takes into account the effects of the magnetic field. Discrepant results between abundances derived from Si ii and Si iii in B-type stars has been documented in the literature. We report on the first comprehensive study of this phenomenon in various classes of B-type stars (including the non-magnetic HgMn and normal stars and magnetic Bp stars) ranging in effective temperature from about 11000 to 15000 K. We interpret the results in the context of vertical stratification in the atmospheres of these stars. The abundance anomalies that exist in magnetic Ap/Bp stars are known to be produced by diffusion processes, when the gravitational settling of ions competes with radiative levitation. However, nothing is known about how these abundance anomalies may evolve during the main sequence lifetime of these stars. We present an extensive study of the atmospheric abundances for several elements of magnetic Ap/Bp stars, that are members of open clusters or associations (and therefore have well-determined ages), and attempt to interpret the results in the context of diffusion. Keywords: Stars: abundances, chemically peculiar, magnetic field ii Co-Authorship Statement This thesis is based on work done in collaboration with several co-authors including my super- visor J. D. Landstreet, as well as G. Wade, S. Bagnulo, J. Grunhut, M. Shultz, D. Bohlender, J. Lim, K. Wong, S. Drake, and J. Linksy. Below, I briefly describe my contributions to each project. Chapter 2: This chapter presents the extensive study of HD 133880. This project was the idea of myself, D. Bohlender and G. Wade. I was responsible for determining the star’s physical parameters, deriving the magnetic field model (including the magnetic field modulus mea- surements) and performing the abundance analysis. I wrote the majority of the manuscript, excluding the sections on the period refinement and magnetosphere (G. Wade), the line profile variations (J. Grunhut) and the longitudinal magnetic field measurements (M. Shultz). Chapter 3: This chapter presents the investigation of HD 147010. I envisioned this entire project and am responsible for writing the observing proposal that collected the data used. I performed all the analysis and wrote the entire manuscript. Chapter 4: This chapter investigates the abundances determined using lines of Si ii and Si iii in B-type stars. This project was based on my analysis under the guidance of J. D. Landstreet. I am responsible for the majority of the manuscript, excluding the stratification and non-LTE effects. Chapter 5: This chapter presents the study of the time evolution of abundances in magnetic Bp stars. This project was the idea of J. D. Landstreet, but I performed all the analysis. The discussion section was mainly the work of J. D. Landstreet, with some input from me. All other aspects of the paper were written exclusively by me, with suggestions from J. D. Landstreet. iii Acknowledgements I have had the distinct pleasure of being supervised by John D. Landstreet. I thank him for his dedication, guidance and patience. It is my sincere hope that I can inject my career with the same unwavering enthusiasm and love of science that John has displayed over the past five years that I have been at Western. To my parents, Raymond and Johanna Bailey. Words cannot adequately express how im- portant they are to me, nor the role they played in making me the man I am today. I thank them for their unconditional love, support and for affording me the opportunity to fulfill my potential. If asked, they will say that they are proud of what I have accomplished. To them I say that I am proud to be your son. To the rest of my family, I thank you for your support and for always showing interest in my endeavours. To my friends, Robbie Halonen, Alex DeSouza, Allison Hill and Megan Mattos. I thank you for necessary distractions and for friendships that will last a lifetime. Lastly, I’d like to thank the love of my life, my wife Nicole Bailey. You are my best friend and I can’t imagine a more fitting partner to journey through life with. I thank you for being my sounding board, for your encouragement and for your confidence in me. iv Contents Abstract ii Co-Authorship Statement iii Acknowledgements iv List of Figures x List of Tables xiv List of Abbreviations, Symbols, and Nomenclature xvi 1 Introduction 1 1.1 A-andlateBstars:apeculiarlot . ..... 5 1.1.1 Non-magneticstars ............................ 5 Amstars.................................. 5 HgMnstars ................................ 5 1.1.2 Magneticstars............................... 6 Ap/Bpstars ................................ 6 1.2 Diffusionprocesses ................................ 8 1.3 NatureofmagneticfieldsinA-andB-typestars . ........ 9 1.3.1 Origin................................... 9 1.3.2 Mainsequenceevolution . 10 1.4 Measurementofmagneticfieldsinstars . ...... 11 1.4.1 BasicPhysics ............................... 11 PolarisationofZeemancomponents . 12 1.4.2 Detectingmagnetisminstars . .. 12 1.5 Spectrallineformation . ... 13 1.5.1 Equationofradiativetransfer . .... 14 1.5.2 SpectralLines............................... 15 v AbsorptionFeatures. 16 1.5.3 Polarisation and the equations of radiative transfer ............ 17 1.6 SpectrumSynthesis ............................... 18 1.6.1 Computing emergent spectra with zeeman ................ 18 Illustrativeexamples . 19 1.7 AbundanceanalysisofmagneticBpstars. ....... 21 Bibliography....................................... 21 2 TherapidlyrotatingmagneticBpstarHD133880 25 2.1 Introduction .................................... 25 2.2 Observations.................................... 26 2.2.1 Polarisedspectra ............................. 26 2.2.2 Unpolarisedspectra. 28 2.2.3 LongitudinalMagneticFieldMeasurements . ...... 28 2.2.4 ATCAradiocontinuummeasurements . .. 30 2.3 Rotationperiod .................................. 31 2.4 DeterminationofPhysicalParameters . ....... 32 2.4.1 EffectiveTemperature. 32 2.4.2 Luminosity ................................ 34 2.4.3 OtherParameters ............................. 34 2.5 Lineprofilevariations. ... 35 2.6 MagneticFieldModel.............................. 35 2.6.1 Surfacemagneticfieldmodulusmeasurements . ..... 39 2.6.2 Magneticfieldgeometry . 40 2.7 AbundanceModel................................. 42 2.7.1 Spectranormalisation. 43 2.7.2 Choiceofmagneticfieldmodel. 44 2.8 Abundanceanalysis............................... 44 2.8.1 Helium .................................. 46 2.8.2 Oxygen .................................. 46 2.8.3 Magnesium ................................ 47 2.8.4 Silicon................................... 47 2.8.5 Titanium.................................. 48 2.8.6 Chromium................................. 48 2.8.7 Iron .................................... 49 2.8.8 Nickel................................... 50 vi 2.8.9 Praseodymium .............................. 50 2.8.10 Neodymium................................ 50 2.9 Magnetosphere .................................. 50 2.10Discussion..................................... 54 Bibliography....................................... 59 3 The surface chemistry of the magnetic Bp star HD 147010 63 3.1 Introduction .................................... 63 3.2 Observations.................................... 64 3.2.1 Longitudinal magnetic
Load more

Recommended publications
  • Type Ia Supernovae, Massive White Dwarfs, and Ap Stars
    Merging of Components in Close Binaries: Type Ia Supernovae, Massive White Dwarfs, and Ap stars A. I. Bogomazov1, A. V. Tutukov2 1 Sternberg Astronomical Institute, Moscow State University, Universitetski pr. 13, Moscow, 119992, Russia, 2 Institute of Astronomy, Russian Academy of Sciences, ul. Pyatnitskaya 48, Moscow, 109017, Russia Astronomy Reports, volume 53, no. 3, pp. 214-222 (2009) The “Scenario Machine” (a computer code designed for studies of the evolution of close bina- ries) was used to carry out a population synthesis for a wide range of merging astrophysical objects: main-sequence stars with main-sequence stars; white dwarfs with white dwarfs, neu- tron stars, and black holes; neutron stars with neutron stars and black holes; and black holes with black holes.We calculate the rates of such events, and plot the mass distributions for merging white dwarfs and main-sequence stars. It is shown that Type Ia supernovae can be used as standard candles only after approximately one billion years of evolution of galaxies. In the course of this evolution, the average energy of Type Ia supernovae should decrease by roughly 10%; the maximum and minimum energies of Type Ia supernovae may differ by no less than by a factor of 1.5. This circumstance should be taken into account in estimations of parameters of acceleration of the Universe. According to theoretical estimates, the most massive – as a rule, magnetic – white dwarfs probably originate from mergers of white dwarfs of lower mass. At least some magnetic Ap and Bp stars may form in mergers of low-mass main-sequence stars (M .
    [Show full text]
  • Tests of Stellar Model Atmospheres by Optical Interferometry IV
    A&A 460, 855–864 (2006) Astronomy DOI: 10.1051/0004-6361:20066032 & c ESO 2006 Astrophysics Tests of stellar model atmospheres by optical interferometry IV. VINCI interferometry and UVES spectroscopy of Menkar M. Wittkowski1, J. P. Aufdenberg2, T. Driebe3, V. Roccatagliata4 , T. Szeifert5,andB.Wolff1 1 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching bei München, Germany e-mail: [email protected] 2 National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA 3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany 4 Max-Planck-Institut für Astronomie, Königsstuhl 17, 69117 Heidelberg, Germany 5 European Southern Observatory, Casilla 19001, Santiago 19, Chile Received 13 July 2006 / Accepted 29 August 2006 ABSTRACT Aims. We present coordinated near-infrared K-band interferometric and optical spectroscopic observations of the M 1.5 giant α Cet (Menkar) obtained with the instruments VINCI and UVES at the Paranal Observatory. Spherically symmetric PHOENIX stellar model atmospheres are constrained by comparison to our interferometric and spectroscopic data, and high-precision fundamental parameters of Menkar are obtained. Methods. Our high-precision VLTI/VINCI observations in the first and second lobes of the visibility function directly probe the model-predicted strength of the limb darkening effect in the K-band and the stellar angular diameter. The high spectral resolution of UVES of R = 80 000–110 000 allows us to confront in detail observed and model-predicted profiles of atomic lines and molecular bands. Results. We show that our derived PHOENIX model atmosphere for Menkar is consistent with both the measured strength of the limb- darkening in the near-infrared K-band and the profiles of spectral bands around selected atomic lines and TiO bandheads from 370 nm to 1000 nm.
    [Show full text]
  • Magnetism, Dynamo Action and the Solar-Stellar Connection
    Living Rev. Sol. Phys. (2017) 14:4 DOI 10.1007/s41116-017-0007-8 REVIEW ARTICLE Magnetism, dynamo action and the solar-stellar connection Allan Sacha Brun1 · Matthew K. Browning2 Received: 23 August 2016 / Accepted: 28 July 2017 © The Author(s) 2017. This article is an open access publication Abstract The Sun and other stars are magnetic: magnetism pervades their interiors and affects their evolution in a variety of ways. In the Sun, both the fields themselves and their influence on other phenomena can be uncovered in exquisite detail, but these observations sample only a moment in a single star’s life. By turning to observa- tions of other stars, and to theory and simulation, we may infer other aspects of the magnetism—e.g., its dependence on stellar age, mass, or rotation rate—that would be invisible from close study of the Sun alone. Here, we review observations and theory of magnetism in the Sun and other stars, with a partial focus on the “Solar-stellar connec- tion”: i.e., ways in which studies of other stars have influenced our understanding of the Sun and vice versa. We briefly review techniques by which magnetic fields can be measured (or their presence otherwise inferred) in stars, and then highlight some key observational findings uncovered by such measurements, focusing (in many cases) on those that offer particularly direct constraints on theories of how the fields are built and maintained. We turn then to a discussion of how the fields arise in different objects: first, we summarize some essential elements of convection and dynamo theory, includ- ing a very brief discussion of mean-field theory and related concepts.
    [Show full text]
  • UC Irvine UC Irvine Previously Published Works
    UC Irvine UC Irvine Previously Published Works Title Astrophysics in 2006 Permalink https://escholarship.org/uc/item/5760h9v8 Journal Space Science Reviews, 132(1) ISSN 0038-6308 Authors Trimble, V Aschwanden, MJ Hansen, CJ Publication Date 2007-09-01 DOI 10.1007/s11214-007-9224-0 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Space Sci Rev (2007) 132: 1–182 DOI 10.1007/s11214-007-9224-0 Astrophysics in 2006 Virginia Trimble · Markus J. Aschwanden · Carl J. Hansen Received: 11 May 2007 / Accepted: 24 May 2007 / Published online: 23 October 2007 © Springer Science+Business Media B.V. 2007 Abstract The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords Cosmology: general · Galaxies: general · ISM: general · Stars: general · Sun: general · Planets and satellites: general · Astrobiology · Star clusters · Binary stars · Clusters of galaxies · Gamma-ray bursts · Milky Way · Earth · Active galaxies · Supernovae 1 Introduction Astrophysics in 2006 modifies a long tradition by moving to a new journal, which you hold in your (real or virtual) hands. The fifteen previous articles in the series are referenced oc- casionally as Ap91 to Ap05 below and appeared in volumes 104–118 of Publications of V.
    [Show full text]
  • A New Magnetic White Dwarf: PG 2329+267
    Mon. Not. R. Astron. Soc. 299, 218–222 (1998) A new magnetic white dwarf: PG 2329+267 C. Moran,1 T. R. Marsh1 and V. S. Dhillon2 1University of Southampton, Department of Physics, Highfield, Southampton SO17 1BJ 2University of Sheffield, Department of Physics, Hounsfield Road, Sheffield S3 7RH Accepted 1998 April 27. Received 1998 April 3; in original form 1997 December 15 ABSTRACT We have discovered that the white dwarf PG 2329+267 is magnetic, and, assuming a centred dipole structure, has a dipole magnetic field strength of approximately 2.3 MG. This makes it one of only approximately 4 per cent of isolated white dwarfs with a detectable magnetic field. Linear Zeeman splitting, as well as quadratic Zeeman shifts, is evident in the hydrogen Balmer sequence and circular spectropolarimetry reveals ,10 per cent circular polarization in the two displaced j components of Ha. We suggest from comparison with spectra of white dwarfs of known mass that PG 2329+267 is more massive than typical isolated white dwarfs, in agreement with the hypothesis that magnetic white dwarfs evolve from magnetic chemically peculiar Ap and Bp type main-sequence stars. Key words: magnetic fields – polarization – stars: individual: PG 2329+267 – white dwarfs. remnants of magnetic main-sequence stars (Sion et al. 1988), as 1 INTRODUCTION well as the observed tendency for magnetic white dwarfs to be more The possibility that white dwarfs may possess large magnetic fields massive than non-magnetic white dwarfs because of their proposed was first suggested in 1947 (Blackett 1947); however, it was not evolution from more massive progenitors.
    [Show full text]
  • Arxiv:1601.04959V1 [Astro-Ph.SR] 19 Jan 2016
    X-rays from magnetic intermediate mass Ap/Bp stars Jan Robrade Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany Abstract The X-ray emission of magnetic intermediate mass Ap/Bp stars is reviewed and put into context of intrinsic as well as extrinsic hypotheses for its origin. New X-ray observations of Ap/Bp stars are presented and combined with an updated analysis of the available datasets, providing the largest sample of its type that is currently available. In the studied stars the X-ray detections are found predominantly among the more massive, hotter and more luminous targets. Their X-ray properties are quite diverse and beside strong soft X-ray emission significant magnetic activity is frequently present. While a connection between more powerful winds and brighter X-ray emission is expected in intrinsic models, the scatter in X-ray luminosity at given bolometric luminosity is so far unexplained and several observational features like X-ray light curves and flaring, luminosity distributions and spectral properties are often similar to those of low-mass stars. It remains to be seen if these features can be fully reproduced by magnetospheres of intermediate mass stars. The article discusses implications for magnetically confined wind-shock models (MCWS) and stellar magnetospheres under the assumption that the intrinsic model is applicable, but also examines the role of possible companions. Further, related magnetospheric phenomena are presented and an outlook on future perspectives is given. Keywords: X-rays: stars, Stars: Ap/Bp, Stars: intermediate mass 1. Introduction indeed likely true for all 'normal' main-sequence stars. See e.g.
    [Show full text]
  • The SDSS Standard BD +17 4708
    A&A 459, 613–625 (2006) Astronomy DOI: 10.1051/0004-6361:20065647 & c ESO 2006 Astrophysics Fundamental parameters and abundances of metal-poor stars: the SDSS standard BD +17 4708 I. Ramírez, C. Allende Prieto, S. Redfield, and D. L. Lambert McDonald Observatory and Department of Astronomy, University of Texas at Austin, RLM 15.306 Austin, TX, 78712-1083, USA e-mail: [ivan;callende;sredfield;dll]@astro.as.utexas.edu Received 22 May 2006 / Accepted 21 August 2006 ABSTRACT The atmospheric parameters and iron abundance of the Sloan Digital Sky Survey (SDSS) spectrophotometric standard star BD +17 4708 are critically examined using up-to-date Kurucz model atmospheres, LTE line formation calculations, and reli- able atomic data. We find Teff = 6141 ± 50 K, log g = 3.87 ± 0.08, and [Fe/H] = −1.74 ± 0.09. The line-of-sight interstellar reddening, bolometric flux, limb-darkened angular diameter, stellar mass, and the abundances of Mg, Si, and Ca are also obtained: −9 −2 −1 E(B−V) = 0.010 ± 0.003, fbol = (4.89±0.10) × 10 erg cm s , θ = 0.1016 ± 0.0023 mas, M = 0.91 ± 0.06 M,[Mg/Fe] = 0.40 ± 0.10, [Si/Fe] = 0.35 ± 0.11, [Ca/Fe] = 0.36 ± 0.11. This star is a unique example of a moderately metal-poor star for which the effective temperature (Teff) can be accurately constrained from the observed spectral energy distribution (corrected for reddening). Such analysis leads to a value that is higher than most spectroscopic results previously reported in the literature (∼5950 K).
    [Show full text]
  • Astronomy Astrophysics
    A&A 454, 321–325 (2006) Astronomy DOI: 10.1051/0004-6361:20064932 & c ESO 2006 Astrophysics Remarkable non-dipolar magnetic field of the Bp star HD 137509 O. Kochukhov Department of Astronomy and Space Physics, Uppsala University, 751 20, Uppsala, Sweden Received 30 January 2006 / Accepted 26 March 2006 ABSTRACT The southern magnetic Bp star HD 137509 exhibits complex rotational modulation of the longitudinal field and other magnetic ob- servables. Interpretation of this magnetic variability in the framework of the low-order multipolar field models suggests a very strong quadrupolar component to dominate the surface field topology of HD 137509. I have examined the high-quality VLT/UVES spectra of HD 137509 and discovered resolved Zeeman split components in some of the spectral lines. The inferred mean surface field modulus, B = 29 kG, agrees with the multipolar model predictions. This confirms the presence of an extremely strong non-dipolar magnetic field in HD 137509 and establishes this star as the object with the second-largest field among magnetic chemically peculiar stars. Key words. line: profiles – stars: magnetic fields – stars: chemically peculiar – stars: individual: HD 137509 1. Introduction suggested quadrupolar and octupolar deviations from the basic dipolar structure reflect the physical reality or represent merely a Significant fraction of the middle and upper main sequence mathematical approximation of the unresolved small-scale field. stars of the B–F spectral classes shows unusual surface prop- Solution of this problem is certainly of great interest because erties. The chemical composition of the outer layers in these it will provide additional important constraints for the theoret- stars departs significantly from solar, with elements distributed ical models of the field generation and evolution in CP stars.
    [Show full text]
  • Arxiv:2001.10147V1
    Magnetic fields in isolated and interacting white dwarfs Lilia Ferrario1 and Dayal Wickramasinghe2 Mathematical Sciences Institute, The Australian National University, Canberra, ACT 2601, Australia Adela Kawka3 International Centre for Radio Astronomy Research, Curtin University, Perth, WA 6102, Australia Abstract The magnetic white dwarfs (MWDs) are found either isolated or in inter- acting binaries. The isolated MWDs divide into two groups: a high field group (105 − 109 G) comprising some 13 ± 4% of all white dwarfs (WDs), and a low field group (B < 105 G) whose incidence is currently under investigation. The situation may be similar in magnetic binaries because the bright accretion discs in low field systems hide the photosphere of their WDs thus preventing the study of their magnetic fields’ strength and structure. Considerable research has been devoted to the vexed question on the origin of magnetic fields. One hypothesis is that WD magnetic fields are of fossil origin, that is, their progenitors are the magnetic main-sequence Ap/Bp stars and magnetic flux is conserved during their evolution. The other hypothesis is that magnetic fields arise from binary interaction, through differential rotation, during common envelope evolution. If the two stars merge the end product is a single high-field MWD. If close binaries survive and the primary develops a strong field, they may later evolve into the arXiv:2001.10147v1 [astro-ph.SR] 28 Jan 2020 magnetic cataclysmic variables (MCVs). The recently discovered population of hot, carbon-rich WDs exhibiting an incidence of magnetism of up to about 70% and a variability from a few minutes to a couple of days may support the [email protected] [email protected] [email protected] Preprint submitted to Journal of LATEX Templates January 29, 2020 merging binary hypothesis.
    [Show full text]
  • Astrophysics in 2006 3
    ASTROPHYSICS IN 2006 Virginia Trimble1, Markus J. Aschwanden2, and Carl J. Hansen3 1 Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, Las Cumbres Observatory, Santa Barbara, CA: ([email protected]) 2 Lockheed Martin Advanced Technology Center, Solar and Astrophysics Laboratory, Organization ADBS, Building 252, 3251 Hanover Street, Palo Alto, CA 94304: ([email protected]) 3 JILA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder CO 80309: ([email protected]) Received ... : accepted ... Abstract. The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords: cosmology: general, galaxies: general, ISM: general, stars: general, Sun: gen- eral, planets and satellites: general, astrobiology CONTENTS 1. Introduction 6 1.1 Up 6 1.2 Down 9 1.3 Around 10 2. Solar Physics 12 2.1 The solar interior 12 2.1.1 From neutrinos to neutralinos 12 2.1.2 Global helioseismology 12 2.1.3 Local helioseismology 12 2.1.4 Tachocline structure 13 arXiv:0705.1730v1 [astro-ph] 11 May 2007 2.1.5 Dynamo models 14 2.2 Photosphere 15 2.2.1 Solar radius and rotation 15 2.2.2 Distribution of magnetic fields 15 2.2.3 Magnetic flux emergence rate 15 2.2.4 Photospheric motion of magnetic fields 16 2.2.5 Faculae production 16 2.2.6 The photospheric boundary of magnetic fields 17 2.2.7 Flare prediction from photospheric fields 17 c 2008 Springer Science + Business Media.
    [Show full text]
  • Gravitational Waves from Neutron Star Magnetic Explosions
    Gravitational Waves from Neutron Star Magnetic Explosions Emily Kuhn, Brynmor Haskell, Andrew Melatos, Paul Lasky, Patrick Clearwater August 11, 2015 Abstract The detection of gravitational waves is one of the most anticipated events in modern science. Postu- lated by Albert Einstein in his 1915 Theory of Gravity, these phenomena are thought to hold important insights into the workings and origin of our universe. Many sources of gravitational wave signals are being explored in an e↵ort towards first detection, one of these being highly magnetic neutron stars known as magnetars. We use the numerical code PLUTO to simulate magnetars and their development over Alfven time scales, in order to determine whether they have potential to produce detectable signals. We investigate two field configurations and their evolutions, finding that the wave strain produced is sufficient to make certain neutron stars candidates for LIGO. 1 Introduction 1.1 Gravitational Waves Albert Einstein first postulated gravitational waves as part of his theory of gravity. Gravitational waves, as we understand them, arise when a massive body undergoes an acceleration, provided the motion is not spherically or cylindrically symmetric, and are the result of a time varying quadrupole. These waves are in the form of three types of signals: 1. Inspirals, which describe a signal increasing in frequency as two objects coalesce, such as from a system 1 of binary black holes or neutron stars 2. Bursts, which characterize a short non-repeating signal, and are the product of such things as super- novae explosions 3. Continuous Signals, which are steady and consistent and from such sources as rotating asymmetric stars.
    [Show full text]
  • O/IR Polarimetry for the 2010 Decade (SSE): Science at the Edge, Sharp Tools for All
    O/IR Polarimetry for the 2010 Decade (SSE): Science at the Edge, Sharp Tools for All A Science White Paper for the Stars and Stellar Evolution (SSE) Science Frontiers Panel of the Astro2010 Decadal Survey Committee Lead Authors: Jennifer L. Hoffman Physics and Astronomy University of Denver 2112 E. Wesley Ave. Denver, CO 80208 (303) 871–2268 [email protected] Dean C. Hines Space Science Institute New Mexico Office 405 Alamos Rd. Corrales, NM 87048 (505) 239-6762 [email protected] Surface magnetic field of the B0.5V star ! Sco, which shows a strongly non-dipolar field topology (Donati et al. 2006)." Contributors and Signatories Andy Adamson UKIRT, JAC, Hilo B-G Andersson Stratospheric Observatory for Infrared Astronomy Karen Bjorkman University of Toledo Ryan Chornock University of California, Berkeley Dan Clemens Boston University James De Buizer SOFIA, NASA Ames Nicholas M. Elias II Universität Heidelberg; MPIA Richard Ignace East Tennessee State University Terry Jay Jones University of Minnesota Alexander Lazarian University of Wisconsin Douglas C. Leonard San Diego State University Antonio Mario Magalhaes University of Sao Paulo, Brazil Marshall Perrin UCLA Claudia Vilega Rodrigues Inst. Nac. De Pesquisas Espaciais, Brazil Hiroko Shinnaga CalTech William Sparks STScI Lifan Wang Texas A&M University Overview and Context: Polarimetry as a cross-cutting enterprise Photometry, spectroscopy, and polarimetry together comprise the basic toolbox astronomers use to discover the nature of the universe. Polarimetry established the Unified Model of AGN and continues to yield unique and powerful insight into complex phenomena. Polarimetry reveals the elusive magnetic field in the Milky Way and external galaxies, allows mapping of features of unresolved stars and supernovae, uncovers nearby exoplanets and faint circumstellar disks, and probes acoustic oscillations of the early universe.
    [Show full text]