Astronomy Div C 2014 Help Session V0
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Plasma Physics and Pulsars
Plasma Physics and Pulsars On the evolution of compact o bjects and plasma physics in weak and strong gravitational and electromagnetic fields by Anouk Ehreiser supervised by Axel Jessner, Maria Massi and Li Kejia as part of an internship at the Max Planck Institute for Radioastronomy, Bonn March 2010 2 This composition was written as part of two internships at the Max Planck Institute for Radioastronomy in April 2009 at the Radiotelescope in Effelsberg and in February/March 2010 at the Institute in Bonn. I am very grateful for the support, expertise and patience of Axel Jessner, Maria Massi and Li Kejia, who supervised my internship and introduced me to the basic concepts and the current research in the field. Contents I. Life-cycle of stars 1. Formation and inner structure 2. Gravitational collapse and supernova 3. Star remnants II. Properties of Compact Objects 1. White Dwarfs 2. Neutron Stars 3. Black Holes 4. Hypothetical Quark Stars 5. Relativistic Effects III. Plasma Physics 1. Essentials 2. Single Particle Motion in a magnetic field 3. Interaction of plasma flows with magnetic fields – the aurora as an example IV. Pulsars 1. The Discovery of Pulsars 2. Basic Features of Pulsar Signals 3. Theoretical models for the Pulsar Magnetosphere and Emission Mechanism 4. Towards a Dynamical Model of Pulsar Electrodynamics References 3 Plasma Physics and Pulsars I. The life-cycle of stars 1. Formation and inner structure Stars are formed in molecular clouds in the interstellar medium, which consist mostly of molecular hydrogen (primordial elements made a few minutes after the beginning of the universe) and dust. -
Negreiros Lecture II
General Relativity and Neutron Stars - II Rodrigo Negreiros – UFF - Brazil Outline • Compact Stars • Spherically Symmetric • Rotating Compact Stars • Magnetized Compact Stars References for this lecture Compact Stars • Relativistic stars with inner structure • We need to solve Einstein’s equation for the interior as well as the exterior Compact Stars - Spherical • We begin by writing the following metric • Which leads to the following components of the Riemman curvature tensor Compact Stars - Spherical • The Ricci tensor components are calculated as • Ricci scalar is given by Compact Stars - Spherical • Now we can calculate Einstein’s equation as 휇 • Where we used a perfect fluid as sources ( 푇휈 = 푑푖푎푔(휖, 푃, 푃, 푃)) Compact Stars - Spherical • Einstein’s equation define the space-time curvature • We must also enforce energy-momentum conservation • This implies that • Where the four velocity is given by • After some algebra we get Compact Stars - Spherical • Making use of Euler’s equation we get • Thus • Which we can rewrite as Compact Stars - Spherical • Now we introduce • Which allow us to integrate one of Einstein’s equation, leading to • After some shuffling of Einstein’s equation we can write Summary so far... Metric Energy-Momentum Tensor Einstein’s equation Tolmann-Oppenheimer-Volkoff eq. Relativistic Hydrostatic Equilibrium Mass continuity Stellar structure calculation Microscopic Ewuation of State Macroscopic Composition Structure Recapitulando … “Feed” with diferente microscopic models Microscopic Ewuation of State Macroscopic Composition Structure Compare predicted properties with Observed data. Rotating Compact Stars • During its evolution, compact stars may acquire high rotational frequencies (possibly up to 500 hz) • Rotation breaks spherical symmetry, increasing the degrees of freedom. -
Exploring Pulsars
High-energy astrophysics Explore the PUL SAR menagerie Astronomers are discovering many strange properties of compact stellar objects called pulsars. Here’s how they fit together. by Victoria M. Kaspi f you browse through an astronomy book published 25 years ago, you’d likely assume that astronomers understood extremely dense objects called neutron stars fairly well. The spectacular Crab Nebula’s central body has been a “poster child” for these objects for years. This specific neutron star is a pulsar that I rotates roughly 30 times per second, emitting regular appar- ent pulsations in Earth’s direction through a sort of “light- house” effect as the star rotates. While these textbook descriptions aren’t incorrect, research over roughly the past decade has shown that the picture they portray is fundamentally incomplete. Astrono- mers know that the simple scenario where neutron stars are all born “Crab-like” is not true. Experts in the field could not have imagined the variety of neutron stars they’ve recently observed. We’ve found that bizarre objects repre- sent a significant fraction of the neutron star population. With names like magnetars, anomalous X-ray pulsars, soft gamma repeaters, rotating radio transients, and compact Long the pulsar poster child, central objects, these bodies bear properties radically differ- the Crab Nebula’s central object is a fast-spinning neutron star ent from those of the Crab pulsar. Just how large a fraction that emits jets of radiation at its they represent is still hotly debated, but it’s at least 10 per- magnetic axis. Astronomers cent and maybe even the majority. -
Surface Structure of Quark Stars with Magnetic Fields
PRAMANA °c Indian Academy of Sciences Vol. 67, No. 5 | journal of November 2006 physics pp. 937{949 Surface structure of quark stars with magnetic ¯elds PRASHANTH JAIKUMAR Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA E-mail: [email protected] Abstract. We investigate the impact of magnetic ¯elds on the electron distribution of the electrosphere of quark stars. For moderately strong magnetic ¯elds of B » 1013 G, quantization e®ects are generally weak due to the large number density of electrons at surface, but can nevertheless a®ect the photon emission properties of quark stars. We outline the main observational characteristics of quark stars as determined by their surface emission, and briefly discuss their formation in explosive events termed as quark-novae, which may be connected to the r-process. Keywords. Quark stars; magnetic ¯elds; nucleosynthesis. PACS Nos 26.60.+c; 24.85.+p; 97.60.Jd 1. Introduction There is a renewed interest in the theory and observation of strange quark stars, which are believed to contain, or be entirely composed of, decon¯ned quark mat- ter [1]. An observational con¯rmation of their existence would be conclusive ev- idence of quark decon¯nement at large baryon densities, an expected feature of quantum chromodynamics (QCD). Furthermore, discovery of a stable bare quark star a±rms the Bodmer{Terazawa{Witten conjecture [2], that at high enough den- sity, strange quark matter, composed of up, down and strange quarks, is absolutely stable with respect to nuclear matter. This intriguing hypothesis is over three decades old, and bare quark stars are but one possible realization put forward in the intervening years. -
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. 25 December 1996 http://webhead.com/∼sergio/hot/ editor: Philippe Eenens http://www.inaoep.mx/∼eenens/hot/ [email protected] http://www.star.ucl.ac.uk/∼hsn/index.html Contents of this Newsletter Abstracts of 6 accepted papers . 1 Abstracts of 2 submitted papers . .4 Abstracts of 3 proceedings papers . 6 Abstract of 1 dissertation thesis . 7 Book .......................................................................8 Meeting .....................................................................8 Accepted Papers The Mass-Loss History of the Symbiotic Nova RR Tel Harry Nussbaumer and Thomas Dumm Institute of Astronomy, ETH-Zentrum, CH-8092 Z¨urich, Switzerland Mass loss in symbiotic novae is of interest to the theory of nova-like events as well as to the question whether symbiotic novae could be precursors of type Ia supernovae. RR Tel began its outburst in 1944. It spent five years in an extended state with no mass-loss before slowly shrinking and increasing its effective temperature. This transition was accompanied by strong mass-loss which decreased after 1960. IUE and HST high resolution spectra from 1978 to 1995 show no trace of mass-loss. Since 1978 the total luminosity has been decreasing at approximately constant effective temperature. During the present outburst the white dwarf in RR Tel will have lost much less matter than it accumulated before outburst. - The 1995 continuum at λ ∼< 1400 is compatible with a hot star of T = 140 000 K, R = 0.105 R , and L = 3700 L . Accepted by Astronomy & Astrophysics Preprints from [email protected] 1 New perceptions on the S Dor phenomenon and the micro variations of five Luminous Blue Variables (LBVs) A.M. -
White Dwarfs and Electron Degeneracy
White Dwarfs and Electron Degeneracy Farley V. Ferrante Southern Methodist University Sirius A and B 27 March 2017 SMU PHYSICS 1 Outline • Stellar astrophysics • White dwarfs • Dwarf novae • Classical novae • Supernovae • Neutron stars 27 March 2017 SMU PHYSICS 2 27 March 2017 SMU PHYSICS 3 Pogson’s ratio: 5 100≈ 2.512 27 March 2017 M.S. Physics Thesis Presentation 4 Distance Modulus mM−=5 log10 ( d) − 1 • Absolute magnitude (M) • Apparent magnitude of an object at a standard luminosity distance of exactly 10.0 parsecs (~32.6 ly) from the observer on Earth • Allows true luminosity of astronomical objects to be compared without regard to their distances • Unit: parsec (pc) • Distance at which 1 AU subtends an angle of 1″ • 1 AU = 149 597 870 700 m (≈1.50 x 108 km) • 1 pc ≈ 3.26 ly • 1 pc ≈ 206 265 AU 27 March 2017 SMU PHYSICS 5 Stellar Astrophysics • Stefan-Boltzmann Law: 54 2π k − − −− FT=σσ4; = = 5.67x 10 5 ergs 1 cm 24 K bol 15ch23 • Effective temperature of a star: Temp. of a black body with the same luminosity per surface area • Stars can be treated as black body radiators to a good approximation • Effective surface temperature can be obtained from the B-V color index with the Ballesteros equation: 11 T = 4600+ 0.92(BV−+) 1.70 0.92(BV −+) 0.62 • Luminosity: 24 L= 4πσ rT* E 27 March 2017 SMU PHYSICS 6 H-R Diagram 27 March 2017 SMU PHYSICS 8 27 March 2017 SMU PHYSICS 9 White dwarf • Core of solar mass star • Pauli exclusion principle: Electron degeneracy • Degenerate Fermi gas of oxygen and carbon • 1 teaspoon would weigh 5 tons • No energy produced from fusion or gravitational contraction Hot white dwarf NGC 2440. -
The Very Long Mystery of Epsilon Aurigae
A Unique Eclipsing Variable TheThe VeryVery LongLong MMysteryystery ofof EpsilonEpsilon AAurigaeurigae robertrobert e. sstenceltencel one of the great scientifi c advances of the 20th A remarkable naked-eye star century was the theory of stellar evolution, as physicists worked out not just how stars shine, but how they origi- will soon start dimming for nate, live, change, and die. To test theory against reality, however, astronomers had to determine accurate masses the eighth time since 1821. for many diff erent kinds of stars — and this meant analyz- What’s going on is still ing the motions of binary pairs. Theorists also needed the stars’ exact diameters, and this meant analyzing the light not exactly clear. curves of eclipsing binaries in particular. A century ago, S&T ILLUSTRATION BY CASEY REED giants of early astrophysics worked intensely on the prob- lem of eclipsing-binary analysis. Henry Norris Russell’s paper “On the Determination of the Orbital Elements of Eclipsing Variable Stars,” published in 1912, set the stage for what followed. BIG WHITE STAR, BIGGER BLACK PARTNER Epsilon Aurigae, hotter than the Sun and larger than Earth’s entire orbit, pours forth some 130,000 times the Sun’s light — which is why it shines as brightly as 3rd magnitude even from 2,000 light-years away. According to the currently favored model, a long, dark object will start sliding across its middle this summer. The object seems to be an opaque warped disk 10 a.u. wide and appearing roughly 1 a.u. tall. Whatever lies at its center seems to be hidden — though there’s also evidence that we see right through the center. -
Revisiting the Pre-Main-Sequence Evolution of Stars I. Importance of Accretion Efficiency and Deuterium Abundance ?
Astronomy & Astrophysics manuscript no. Kunitomo_etal c ESO 2018 March 22, 2018 Revisiting the pre-main-sequence evolution of stars I. Importance of accretion efficiency and deuterium abundance ? Masanobu Kunitomo1, Tristan Guillot2, Taku Takeuchi,3,?? and Shigeru Ida4 1 Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan e-mail: [email protected] 2 Université de Nice-Sophia Antipolis, Observatoire de la Côte d’Azur, CNRS UMR 7293, 06304 Nice CEDEX 04, France 3 Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan 4 Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan Received 5 February 2016 / Accepted 6 December 2016 ABSTRACT Context. Protostars grow from the first formation of a small seed and subsequent accretion of material. Recent theoretical work has shown that the pre-main-sequence (PMS) evolution of stars is much more complex than previously envisioned. Instead of the traditional steady, one-dimensional solution, accretion may be episodic and not necessarily symmetrical, thereby affecting the energy deposited inside the star and its interior structure. Aims. Given this new framework, we want to understand what controls the evolution of accreting stars. Methods. We use the MESA stellar evolution code with various sets of conditions. In particular, we account for the (unknown) efficiency of accretion in burying gravitational energy into the protostar through a parameter, ξ, and we vary the amount of deuterium present. Results. We confirm the findings of previous works that, in terms of evolutionary tracks on the Hertzsprung-Russell (H-R) diagram, the evolution changes significantly with the amount of energy that is lost during accretion. -
JOHN R. THORSTENSEN Address
CURRICULUM VITAE: JOHN R. THORSTENSEN Address: Department of Physics and Astronomy Dartmouth College 6127 Wilder Laboratory Hanover, NH 03755-3528; (603)-646-2869 [email protected] Undergraduate Studies: Haverford College, B. A. 1974 Astronomy and Physics double major, High Honors in both. Graduate Studies: Ph. D., 1980, University of California, Berkeley Astronomy Department Dissertation : \Optical Studies of Faint Blue X-ray Stars" Graduate Advisor: Professor C. Stuart Bowyer Employment History: Department of Physics and Astronomy, Dartmouth College: { Professor, July 1991 { present { Associate Professor, July 1986 { July 1991 { Assistant Professor, September 1980 { June 1986 Research Assistant, Space Sciences Lab., U.C. Berkeley, 1975 { 1980. Summer Student, National Radio Astronomy Observatory, 1974. Summer Student, Bartol Research Foundation, 1973. Consultant, IBM Corporation, 1973. (STARMAP program). Honors and Awards: Phi Beta Kappa, 1974. National Science Foundation Graduate Fellow, 1974 { 1977. Dorothea Klumpke Roberts Award of the Berkeley Astronomy Dept., 1978. Professional Societies: American Astronomical Society Astronomical Society of the Pacific International Astronomical Union Lifetime Publication List * \Can Collapsed Stars Close the Universe?" Thorstensen, J. R., and Partridge, R. B. 1975, Ap. J., 200, 527. \Optical Identification of Nova Scuti 1975." Raff, M. I., and Thorstensen, J. 1975, P. A. S. P., 87, 593. \Photometry of Slow X-ray Pulsars II: The 13.9 Minute Period of X Persei." Margon, B., Thorstensen, J., Bowyer, S., Mason, K. O., White, N. E., Sanford, P. W., Parkes, G., Stone, R. P. S., and Bailey, J. 1977, Ap. J., 218, 504. \A Spectrophotometric Survey of the A 0535+26 Field." Margon, B., Thorstensen, J., Nelson, J., Chanan, G., and Bowyer, S. -
Pos(INTEGRAL 2010)091
A candidate former companion star to the Magnetar CXOU J164710.2-455216 in the massive Galactic cluster Westerlund 1 PoS(INTEGRAL 2010)091 P.J. Kavanagh 1 School of Physical Sciences and NCPST, Dublin City University Glasnevin, Dublin 9, Ireland E-mail: [email protected] E.J.A. Meurs School of Cosmic Physics, DIAS, and School of Physical Sciences, DCU Glasnevin, Dublin 9, Ireland E-mail: [email protected] L. Norci School of Physical Sciences and NCPST, Dublin City University Glasnevin, Dublin 9, Ireland E-mail: [email protected] Besides carrying the distinction of being the most massive young star cluster in our Galaxy, Westerlund 1 contains the notable Magnetar CXOU J164710.2-455216. While this is the only collapsed stellar remnant known for this cluster, a further ~10² Supernovae may have occurred on the basis of the cluster Initial Mass Function, possibly all leaving Black Holes. We identify a candidate former companion to the Magnetar in view of its high proper motion directed away from the Magnetar region, viz. the Luminous Blue Variable W243. We discuss the properties of W243 and how they pertain to the former Magnetar companion hypothesis. Binary evolution arguments are employed to derive a progenitor mass for the Magnetar of 24-25 M Sun , just within the progenitor mass range for Neutron Star birth. We also draw attention to another candidate to be member of a former massive binary. 8th INTEGRAL Workshop “The Restless Gamma-ray Universe” Dublin, Ireland September 27-30, 2010 1 Speaker Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. -
Luminous Blue Variables
Review Luminous Blue Variables Kerstin Weis 1* and Dominik J. Bomans 1,2,3 1 Astronomical Institute, Faculty for Physics and Astronomy, Ruhr University Bochum, 44801 Bochum, Germany 2 Department Plasmas with Complex Interactions, Ruhr University Bochum, 44801 Bochum, Germany 3 Ruhr Astroparticle and Plasma Physics (RAPP) Center, 44801 Bochum, Germany Received: 29 October 2019; Accepted: 18 February 2020; Published: 29 February 2020 Abstract: Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our current knowledge of LBVs is limited by the fact that in comparison to other stellar classes and phases only a few “true” LBVs are known. This results from the lack of a unique, fast and always reliable identification scheme for LBVs. It literally takes time to get a true classification of a LBV. In addition the short duration of the LBV phase makes it even harder to catch and identify a star as LBV. We summarize here what is known so far, give an overview of the LBV population and the list of LBV host galaxies. LBV are clearly an important and still not fully understood phase in the live of (very) massive stars, especially due to the large and time variable mass loss during the LBV phase. We like to emphasize again the problem how to clearly identify LBV and that there are more than just one type of LBVs: The giant eruption LBVs or h Car analogs and the S Dor cycle LBVs. -
Aerodynamic Phenomena in Stellar Atmospheres, a Bibliography
- PB 151389 knical rlote 91c. 30 Moulder laboratories AERODYNAMIC PHENOMENA STELLAR ATMOSPHERES -A BIBLIOGRAPHY U. S. DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS ^M THE NATIONAL BUREAU OF STANDARDS Functions and Activities The functions of the National Bureau of Standards are set forth in the Act of Congress, March 3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and technical problems; in- vention and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications. The work includes basic and applied research, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover. Publications The results of the Bureau's work take the form of either actual equipment and devices or pub- lished papers.