Plasma Physics and Pulsars
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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. -
Beyond the Solar System Homework for Geology 8
DATE DUE: Name: Ms. Terry J. Boroughs Geology 8 Section: Beyond the Solar System Instructions: Read each question carefully before selecting the BEST answer. Use GEOLOGIC VOCABULARY where APPLICABLE! Provide concise, but detailed answers to essay and fill-in questions. Use an 882-e scantron for your multiple choice and true/false answers. Multiple Choice 1. Which one of the objects listed below has the largest size? A. Galactic clusters. B. Galaxies. C. Stars. D. Nebula. E. Planets. 2. Which one of the objects listed below has the smallest size? A. Galactic clusters. B. Galaxies. C. Stars. D. Nebula. E. Planets. 3. The Sun belongs to this class of stars. A. Black hole C. Black dwarf D. Main-sequence star B. Red giant E. White dwarf 4. The distance to nearby stars can be determined from: A. Fluorescence. D. Stellar parallax. B. Stellar mass. E. Emission nebulae. C. Stellar distances cannot be measured directly 5. Hubble's law states that galaxies are receding from us at a speed that is proportional to their: A. Distance. B. Orientation. C. Galactic position. D. Volume. E. Mass. 6. Our galaxy is called the A. Milky Way galaxy. D. Panorama galaxy. B. Orion galaxy. E. Pleiades galaxy. C. Great Galaxy in Andromeda. 7. The discovery that the universe appears to be expanding led to a widely accepted theory called A. The Big Bang Theory. C. Hubble's Law. D. Solar Nebular Theory B. The Doppler Effect. E. The Seyfert Theory. 8. One of the most common units used to express stellar distances is the A. -
XIII Publications, Presentations
XIII Publications, Presentations 1. Refereed Publications E., Kawamura, A., Nguyen Luong, Q., Sanhueza, P., Kurono, Y.: 2015, The 2014 ALMA Long Baseline Campaign: First Results from Aasi, J., et al. including Fujimoto, M.-K., Hayama, K., Kawamura, High Angular Resolution Observations toward the HL Tau Region, S., Mori, T., Nishida, E., Nishizawa, A.: 2015, Characterization of ApJ, 808, L3. the LIGO detectors during their sixth science run, Classical Quantum ALMA Partnership, et al. including Asaki, Y., Hirota, A., Nakanishi, Gravity, 32, 115012. K., Espada, D., Kameno, S., Sawada, T., Takahashi, S., Ao, Y., Abbott, B. P., et al. including Flaminio, R., LIGO Scientific Hatsukade, B., Matsuda, Y., Iono, D., Kurono, Y.: 2015, The 2014 Collaboration, Virgo Collaboration: 2016, Astrophysical Implications ALMA Long Baseline Campaign: Observations of the Strongly of the Binary Black Hole Merger GW150914, ApJ, 818, L22. Lensed Submillimeter Galaxy HATLAS J090311.6+003906 at z = Abbott, B. P., et al. including Flaminio, R., LIGO Scientific 3.042, ApJ, 808, L4. Collaboration, Virgo Collaboration: 2016, Observation of ALMA Partnership, et al. including Asaki, Y., Hirota, A., Nakanishi, Gravitational Waves from a Binary Black Hole Merger, Phys. Rev. K., Espada, D., Kameno, S., Sawada, T., Takahashi, S., Kurono, Lett., 116, 061102. Y., Tatematsu, K.: 2015, The 2014 ALMA Long Baseline Campaign: Abbott, B. P., et al. including Flaminio, R., LIGO Scientific Observations of Asteroid 3 Juno at 60 Kilometer Resolution, ApJ, Collaboration, Virgo Collaboration: 2016, GW150914: Implications 808, L2. for the Stochastic Gravitational-Wave Background from Binary Black Alonso-Herrero, A., et al. including Imanishi, M.: 2016, A mid-infrared Holes, Phys. -
Collapsing Supra-Massive Magnetars: Frbs, the Repeating FRB121102 and Grbs
J. Astrophys. Astr. (2018) 39:14 © Indian Academy of Sciences https://doi.org/10.1007/s12036-017-9499-9 Review Collapsing supra-massive magnetars: FRBs, the repeating FRB121102 and GRBs PATRICK DAS GUPTA∗ and NIDHI SAINI Department of Physics and Astrophysics, University of Delhi, Delhi 110007, India. ∗Corresponding author. E-mail: [email protected], [email protected] MS received 30 August 2017; accepted 3 October 2017; published online 10 February 2018 Abstract. Fast Radio Bursts (FRBs) last for ∼ few milli-seconds and, hence, are likely to arise from the gravitational collapse of supra-massive, spinning neutron stars after they lose the centrifugal support (Falcke & Rezzolla 2014). In this paper, we provide arguments to show that the repeating burst, FRB 121102, can also be modeled in the collapse framework provided the supra-massive object implodes either into a Kerr black hole surrounded by highly magnetized plasma or into a strange quark star. Since the estimated rates of FRBs and SN Ib/c are comparable, we put forward a common progenitor scenario for FRBs and long GRBs in which only those compact remnants entail prompt γ -emission whose kick velocities are almost aligned or anti-aligned with the stellar spin axes. In such a scenario, emission of detectable gravitational radiation and, possibly, of neutrinos are expected to occur during the SN Ib/c explosion as well as, later, at the time of magnetar implosion. Keywords. FRBs—FRB 121102—Kerr black holes—Blandford–Znajek process—strange stars—GRBs— pre-natal kicks. 1. Introduction 43% linear polarization and 3% circular polarization (Petroff et al. -
A Star Is Born
A STAR IS BORN Overview: Students will research the four stages of the life cycle of a star then further research the ramifications of the stage of the sun on Earth. Objectives: The student will: • research, summarize and illustrate the proper sequence in the life cycle of a star; • share findings with peers; and • investigate Earth’s personal star, the sun, and what will eventually come of it. Targeted Alaska Grade Level Expectations: Science [9] SA1.1 The student demonstrates an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [9] SD4.1 The student demonstrates an understanding of the theories regarding the origin and evolution of the universe by recognizing that a star changes over time. [10-11] SA1.1 The student demonstrates an understanding of the processes of science by asking questions, predicting, observing, describing, measuring, classifying, making generalizations, analyzing data, developing models, inferring, and communicating. [10] SD4.1 The student demonstrates an understanding of the theories regarding the origin and evolution of the universe by recognizing phenomena in the universe (i.e., black holes, nebula). [11] SD4.1 The student demonstrates an understanding of the theories regarding the origin and evolution of the universe by describing phenomena in the universe (i.e., black holes, nebula). Vocabulary: black dwarf – the celestial object that remains after a white dwarf has used up all of its -
When Neutron Stars Melt, What’S Left Behind Is Spectacular Explosion
Space oddity implodes. The outer layers are cast off in a When neutron stars melt, what’s left behind is spectacular explosion. What’s left behind is truly strange. Anil Ananthaswamy reports a rapidly spinning neutron star, which as the name implies is made mainly of neutrons, with a crust of iron. Whirling up to 1000 times per second, a neutron star is constantly shedding magnetic fields. Over time, this loss of energy causes the star to spin slower and slower. As it spins down, the centrifugal forces that kept gravity at bay start weakening, allowing gravity to squish the star still further. In what is a blink of an eye in cosmic time, the neutrons can be converted to strange N 22 September last year, the website of fundamental building blocks of matter in quark matter, which is a soup of up, down and The Astronomer’s Telegram alerted ways that even machines like the Large strange quarks. In theory, this unusual change Oresearchers to a supernova explosion in Hadron Collider cannot. happens when the density inside the neutron a spiral galaxy about 84 million light years Astrophysicists can thank string theorist star starts increasing. New particles called away. There was just one problem. The same Edward Witten for quark stars. In 1984, he hyperons begin forming that contain at least object, SN 2009ip, had blown up in a similarly hypothesised that protons and neutrons one strange quark bound to others. spectacular fashion just weeks earlier. Such may not be the most stable forms of matter. However, the appearance of hyperons stars shouldn’t go supernova twice, let alone Both are made of two types of smaller marks the beginning of the end of the neutron in quick succession. -
Exors and the Stellar Birthline Mackenzie S
A&A 600, A133 (2017) Astronomy DOI: 10.1051/0004-6361/201630196 & c ESO 2017 Astrophysics EXors and the stellar birthline Mackenzie S. L. Moody1 and Steven W. Stahler2 1 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA e-mail: [email protected] 2 Astronomy Department, University of California, Berkeley, CA 94720, USA e-mail: [email protected] Received 6 December 2016 / Accepted 23 February 2017 ABSTRACT We assess the evolutionary status of EXors. These low-mass, pre-main-sequence stars repeatedly undergo sharp luminosity increases, each a year or so in duration. We place into the HR diagram all EXors that have documented quiescent luminosities and effective temperatures, and thus determine their masses and ages. Two alternate sets of pre-main-sequence tracks are used, and yield similar results. Roughly half of EXors are embedded objects, i.e., they appear observationally as Class I or flat-spectrum infrared sources. We find that these are relatively young and are located close to the stellar birthline in the HR diagram. Optically visible EXors, on the other hand, are situated well below the birthline. They have ages of several Myr, typical of classical T Tauri stars. Judging from the limited data at hand, we find no evidence that binarity companions trigger EXor eruptions; this issue merits further investigation. We draw several general conclusions. First, repetitive luminosity outbursts do not occur in all pre-main-sequence stars, and are not in themselves a sign of extreme youth. They persist, along with other signs of activity, in a relatively small subset of these objects. -
The Formation of Brown Dwarfs 459
Whitworth et al.: The Formation of Brown Dwarfs 459 The Formation of Brown Dwarfs: Theory Anthony Whitworth Cardiff University Matthew R. Bate University of Exeter Åke Nordlund University of Copenhagen Bo Reipurth University of Hawaii Hans Zinnecker Astrophysikalisches Institut, Potsdam We review five mechanisms for forming brown dwarfs: (1) turbulent fragmentation of molec- ular clouds, producing very-low-mass prestellar cores by shock compression; (2) collapse and fragmentation of more massive prestellar cores; (3) disk fragmentation; (4) premature ejection of protostellar embryos from their natal cores; and (5) photoerosion of pre-existing cores over- run by HII regions. These mechanisms are not mutually exclusive. Their relative importance probably depends on environment, and should be judged by their ability to reproduce the brown dwarf IMF, the distribution and kinematics of newly formed brown dwarfs, the binary statis- tics of brown dwarfs, the ability of brown dwarfs to retain disks, and hence their ability to sustain accretion and outflows. This will require more sophisticated numerical modeling than is presently possible, in particular more realistic initial conditions and more realistic treatments of radiation transport, angular momentum transport, and magnetic fields. We discuss the mini- mum mass for brown dwarfs, and how brown dwarfs should be distinguished from planets. 1. INTRODUCTION form a smooth continuum with those of low-mass H-burn- ing stars. Understanding how brown dwarfs form is there- The existence of brown dwarfs was first proposed on the- fore the key to understanding what determines the minimum oretical grounds by Kumar (1963) and Hayashi and Nakano mass for star formation. In section 3 we review the basic (1963). -
Protostars and Pre-Main-Sequence Stars Jeans' Mass
Protostars and pre-main-sequence stars Jeans’ mass - minimum mass of a gas cloud of temperature T and density r that will collapse under gravity: 3 2 1 2 Ê Rg ˆ Ê 3 ˆ 3 2 -1 2 MJ = Á ˜ Á ˜ T r Ë mG¯ Ë 4p ¯ Several stages of collapse: • Initial isothermal collapse - still optically thin • Collapse† slows or halts once gas becomes optically thick - heats up so pressure becomes important again • Second phase of free-fall collapse as hydrogen molecules are broken up - absorbs energy and robs cloud of pressure support • Finally forms protostar with radius of 5 - 10 Rsun All this happens very rapidly - not easy to observe ASTR 3730: Fall 2003 Observationally, classify young stellar objects (YSOs) by looking at their spectral energy distributions (SEDs). Four main classes of object have been identified: flux Class 0 source wavelength in microns 1 10 100 (10-6 m) Observationally, this is a source whose SED peaks in the far-infrared or mm part of the spectrum. No flux in the near-infrared (at a few microns). Effective temperature is several 10s of degrees Kelvin. ASTR 3730: Fall 2003 What are Class 0 sources? • Still very cool - not much hotter than molecular cloud cores. Implies extreme youth. • Deeply embedded in gas and dust, any shorter wavelength radiation is absorbed and reradiated at longer wavelengths before escaping. • Fairly small numbers - consistent with short duration of the initial collapse. • Outflows are seen - suggests a protostar is forming. Earliest observed stage of star formation… ASTR 3730: Fall 2003 Class 1 flux Very large infrared excess Protostellar black body emission wavelength in microns 1 10 100 (10-6 m) Class 1 sources also have SEDs that rise into the mid and far infrared. -
Equation of State of a Dense and Magnetized Fermion System Israel Portillo Vazquez University of Texas at El Paso, [email protected]
University of Texas at El Paso DigitalCommons@UTEP Open Access Theses & Dissertations 2011-01-01 Equation Of State Of A Dense And Magnetized Fermion System Israel Portillo Vazquez University of Texas at El Paso, [email protected] Follow this and additional works at: https://digitalcommons.utep.edu/open_etd Part of the Physics Commons Recommended Citation Portillo Vazquez, Israel, "Equation Of State Of A Dense And Magnetized Fermion System" (2011). Open Access Theses & Dissertations. 2365. https://digitalcommons.utep.edu/open_etd/2365 This is brought to you for free and open access by DigitalCommons@UTEP. It has been accepted for inclusion in Open Access Theses & Dissertations by an authorized administrator of DigitalCommons@UTEP. For more information, please contact [email protected]. EQUATION OF STATE OF A DENSE AND MAGNETIZED FERMION SYSTEM ISRAEL PORTILLO VAZQUEZ Department of Physics APPROVED: Efrain J. Ferrer , Ph.D., Chair Vivian Incera, Ph.D. Mohamed A. Khamsi, Ph.D. Benjamin C. Flores, Ph.D. Acting Dean of the Graduate School Copyright © by Israel Portillo Vazquez 2011 EQUATION OF STATE OF A DENSE AND MAGNETIZED FERMION SYSTEM by ISRAEL PORTILLO VAZQUEZ, MS THESIS Presented to the Faculty of the Graduate School of The University of Texas at El Paso in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Department of Physics THE UNIVERSITY OF TEXAS AT EL PASO August 2011 Acknowledgements First, I would like to acknowledge the advice and guidance of my mentor Dr. Efrain Ferrer. During the time I have been working with him, the way in which I think about nature has changed considerably. -
Lecture 24. Degenerate Fermi Gas (Ch
Lecture 24. Degenerate Fermi Gas (Ch. 7) We will consider the gas of fermions in the degenerate regime, where the density n exceeds by far the quantum density nQ, or, in terms of energies, where the Fermi energy exceeds by far the temperature. We have seen that for such a gas μ is positive, and we’ll confine our attention to the limit in which μ is close to its T=0 value, the Fermi energy EF. ~ kBT μ/EF 1 1 kBT/EF occupancy T=0 (with respect to E ) F The most important degenerate Fermi gas is 1 the electron gas in metals and in white dwarf nε()(),, T= f ε T = stars. Another case is the neutron star, whose ε⎛ − μ⎞ exp⎜ ⎟ +1 density is so high that the neutron gas is ⎝kB T⎠ degenerate. Degenerate Fermi Gas in Metals empty states ε We consider the mobile electrons in the conduction EF conduction band which can participate in the charge transport. The band energy is measured from the bottom of the conduction 0 band. When the metal atoms are brought together, valence their outer electrons break away and can move freely band through the solid. In good metals with the concentration ~ 1 electron/ion, the density of electrons in the electron states electron states conduction band n ~ 1 electron per (0.2 nm)3 ~ 1029 in an isolated in metal electrons/m3 . atom The electrons are prevented from escaping from the metal by the net Coulomb attraction to the positive ions; the energy required for an electron to escape (the work function) is typically a few eV. -
Condensation of Bosons with Several Degrees of Freedom Condensación De Bosones Con Varios Grados De Libertad
Condensation of bosons with several degrees of freedom Condensación de bosones con varios grados de libertad Trabajo presentado por Rafael Delgado López1 para optar al título de Máster en Física Fundamental bajo la dirección del Dr. Pedro Bargueño de Retes2 y del Prof. Fernando Sols Lucia3 Universidad Complutense de Madrid Junio de 2013 Calificación obtenida: 10 (MH) 1 [email protected], Dep. Física Teórica I, Universidad Complutense de Madrid 2 [email protected], Dep. Física de Materiales, Universidad Complutense de Madrid 3 [email protected], Dep. Física de Materiales, Universidad Complutense de Madrid Abstract The condensation of the spinless ideal charged Bose gas in the presence of a magnetic field is revisited as a first step to tackle the more complex case of a molecular condensate, where several degrees of freedom have to be taken into account. In the charged bose gas, the conventional approach is extended to include the macroscopic occupation of excited kinetic states lying in the lowest Landau level, which plays an essential role in the case of large magnetic fields. In that limit, signatures of two diffuse phase transitions (crossovers) appear in the specific heat. In particular, at temperatures lower than the cyclotron frequency, the system behaves as an effectively one-dimensional free boson system, with the specific heat equal to (1/2) NkB and a gradual condensation at lower temperatures. In the molecular case, which is currently in progress, we have studied the condensation of rotational levels in a two–dimensional trap within the Bogoliubov approximation, showing that multi–step condensation also occurs.