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Helioseismology
Helioseismology, a term coined by Douglas Gough, is the study of the structure and dynamics of the Sun through its oscillations. These are principally caused by sound waves that are continuously driven and damped by convection near the Sun's surface. It is similar to geoseismology, or asteroseismology (also coined by Gough), which are respectively the studies of the Earth or stars through their oscillations. While the Sun's oscillations were first detected in the early 1960s, it was only in the mid-1970s that it was realized that the oscillations propagated throughout the Sun and could allow scientists to study the Sun's deep interior. The modern field is separated into global helioseismology, which studies the Sun's resonant modes directly, and local helioseismology, which studies the propagation of the component waves near the Sun's surface. Helioseismology has contributed to a number of scientific breakthroughs. The most notable was to show the predicted neutrino flux from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Oscillations Network Group
The Global Oscillation Network Group (GONG) is a worldwide network of six identical telescopes, designed to have 24/7 observations of the Sun. The network serves multiple purposes, including the provision of operation data for use in space weather prediction, and the study of solar internal structure and dynamics using helioseismology. Deployed in 1995, GONG is a set of six observing systems geographically distributed around the Earth so that the Sun can be observed as continuously as possible. The six observatories are the Teide Observatory ( Canary Islands), thLearmonth Solar Observatory(Western Australia), the Big Bear Solar Observatory (California), the Mauna Loa Solar Observatory (Hawaii), the Udaipur Solar Observatory (India) and the Cerro Tololo Inter-American Observatory (Chile). With these sites, GONG typically can observe the Sun 91% of the time, 24/7. GONG was constructed to provide observations for helioseismology, which aims to understand the solar interior by analy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jørgen Christensen-Dalsgaard
Jørgen Christensen-Dalsgaard (born 6 October 1950) is a Danish astronomer at Aarhus University in Denmark. He specializes in asteroseismology and helioseismology. He has made significant contributions to both fields, including predicting the oscillation of Sun-like stars in 1983. He is the head of "Rumudvalget" (the committee of space of the Danish Ministry of Science, Technology and Innovation) and the Stellar Astrophysics Centre (SAC) supported by the Danish National Research Foundation. He is co-investigator on the Kepler space telescope, Kepler mission and, with Hans Kjeldsen in Aarhus, leads the 500+ researchers in the Kepler Asteroseismic Science Consortium (KASC). KASC is responsible for the asteroseismology component of the Kepler mission. Christensen-Dalsgaard has published several papers on this subject. He was also previously the president of Commission 27 of the International Astronomical Union. He has been featured on Danish television and radio several times and has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birmingham Solar Oscillations Network
The Birmingham Solar Oscillations Network (BiSON) consists of a network of six remote solar observatories monitoring low-degree solar oscillation modes. It is operated by the High Resolution Optical Spectroscopy group of the School of Physics and Astronomy at the University of Birmingham, UK, in collaboration with Sheffield Hallam University, UK. They are funded by the Science and Technology Facilities Council ( STFC). The BiSON has been collecting data continuously on solar oscillations since 1976, making it the longest running helioseismology network with data covering three solar cycles. Team Academic staff * Professor Yvonne Elsworth (Head of project) * Professor Bill Chaplin Research staff * Anne-Marie Broomhall — Helioseismology * Andrea Miglio * Steven Hale Technical staff * Mr Ian Barnes — Electronics * Mr Barry Jackson — Mechanics Remote observatories BiSON operates automated resonant scattering spectrometers in astronomical domes or mir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Neutrino Problem
The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly. The discrepancy was first observed in the mid-1960s and was resolved around 2002. The flux of neutrinos at Earth is several tens of billions per square centimetre per second, mostly from the Sun's core. They are nevertheless hard to detect, because they interact very weakly with matter, traversing the whole Earth. Of the three types ( flavors) of neutrinos known in the Standard Model of particle physics, the Sun produces only electron neutrinos. When neutrino detectors became sensitive enough to measure the flow of electron neutrinos from the Sun, the number detected was much lower than predicted. In various experiments, the number deficit was between one half and two thirds. Particle physicists knew that a mechanism, discussed back in 1957 by Bruno Pontecorvo, could explain the deficit in electron neutrinos. However, they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tachocline
The tachocline is the transition region of stars of more than 0.3 solar masses, between the radiative interior and the differentially rotating outer convective zone. This causes the region to have a very large shear as the rotation rate changes very rapidly. The convective exterior rotates as a normal fluid with differential rotation with the poles rotating slowly and the equator rotating quickly. The radiative interior exhibits solid-body rotation, possibly due to a fossil field. The rotation rate through the interior is roughly equal to the rotation rate at mid-latitudes, i.e. in-between the rate at the slow poles and the fast equator. Recent results from helioseismology indicate that the tachocline is located at a radius of at most 0.70 times the solar radius (measured from the core, i.e., the surface is at 1 solar radius), with a thickness of 0.04 times the solar radius. This would mean the area has a very large shear profile that is one way that large scale magnetic fields ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Douglas Gough
Douglas Owen Gough FRS (born 8 February 1941)GOUGH, Prof. Douglas Owen ''Who's Who 2014'', A & C Black, 2014; online edn, Oxford University Press, 2014 is a British , Professor Emeritus of Theoretical Astrophysics in the , and Leverhulme Emeritus Fellow. Life Gough was educated at before attending the |
Asteroseismology
Asteroseismology or astroseismology is the study of oscillations in stars. Stars have many resonant modes and frequencies, and the path of sound waves passing through a star depends on the speed of sound, which in turn depends on local temperature and chemical composition. Because the resulting oscillation modes are sensitive to different parts of the star, they inform astronomers about the internal structure of the star, which is otherwise not directly possible from overall properties like brightness and surface temperature. Asteroseismology is closely related to helioseismology, the study of stellar pulsation specifically in the Sun. Though both are based on the same underlying physics, more and qualitatively different information is available for the Sun because its surface can be resolved. Theoretical background By linearly perturbing the equations defining the mechanical equilibrium of a star (i.e. mass conservation and hydrostatic equilibrium) and assuming that the pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and bosons (force-carrying particles). There are three generations of fermions, but ordinary matter is made only from the first fermion generation. The first generation consists of up and down quarks which form protons and neutrons, and electrons and electron neutrinos. The three fundamental interactions known to be mediated by bosons are electromagnetism, the weak interaction, and the strong interaction. Quarks cannot exist on their own but form hadrons. Hadrons that contain an odd number of quarks are called baryons and those that contain an even number are called mesons. Two baryons, the proton and the neutron, make up most of the mass of ordinary matter. Mesons are unstable and the longest-lived last for only a few hundredths of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MDI Medium Angular Degree Power Spectrum
MDI may refer to: Computer science * Media Delivery Index, a metric used in IPTV networks *Medium-dependent interface (MDI) and medium-dependent interface crossover (MDI-X), types of Ethernet port connections *Microsoft Document Imaging Format, a proprietary file format * Mission Data Interface, an interface developed by NUWC Keyport *Multiple-document interface, a type of software application interface *Multi-Draw Indirect, a Rendering technique Health *Major Depression Inventory, a self-report mood inventory developed by the World Health Organization *Metered-dose inhaler, a device that helps deliver a specific amount of medication to the lungs * Multiple drug intake, an unnatural cause of death *Multiple Daily Injections, a technique of intensive insulinotherapy *Mental Development Index, a measure of the cognitive abilities of infants and part of the Bayley Scales of Infant Development Organizations *Management Development Institute, a business school in Gurgaon, India * M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar-like Oscillations
Solar-like oscillations are oscillations in stars that are excited in the same way as those in the Sun, namely by turbulent convection in its outer layers. Stars that show solar-like oscillations are called solar-like oscillators. The oscillations are standing pressure and mixed pressure-gravity modes that are excited over a range in frequency, with the amplitudes roughly following a bell-shaped distribution. Unlike opacity-driven oscillators, all the modes in the frequency range are excited, making the oscillations relatively easy to identify. The surface convection also damps the modes, and each is well-approximated in frequency space by a Lorentzian curve, the width of which corresponds to the lifetime of the mode: the faster it decays, the broader is the Lorentzian. All stars with surface convection zones are expected to show solar-like oscillations, including cool main-sequence stars (up to surface temperatures of about 7000K), subgiants and red giants. Because of the small am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Wave
__NOTOC__ In seismology and other areas involving elastic waves, S waves, secondary waves, or shear waves (sometimes called elastic S waves) are a type of elastic wave and are one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves. S waves are transverse waves, meaning that the direction of particle motion of a S wave is perpendicular to the direction of wave propagation, and the main restoring force comes from shear stress. Therefore, S waves cannot propagate in liquids with zero (or very low) viscosity; however, they may propagate in liquids with high viscosity. The name ''secondary wave'' comes from the fact that they are the second type of wave to be detected by an earthquake seismograph, after the compressional primary wave, or P wave, because S waves travel more slowly in solids. Unlike P waves, S waves cannot travel through the molten outer core of the Earth, and this causes a shadow zone for S w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HMI 2D Solar Rotation Profile
HMI may refer to: Companies and organizations * Hahn-Meitner-Institut, now Helmholtz-Zentrum Berlin, a German research institute * Hanson Musical Instruments, a manufacturer of electric guitars * Hartz Mountain Industries, an American holding company * HD Mining International, a mining company in Vancouver, British Columbia, Canada * Hetrick-Martin Institute, a LGBT youth organization in New York City * High Mountain Institute, in Leadville, Colorado, United States * Himalayan Mountaineering Institute, in Darjeeling, India * HMI Hotel Group, a hotel management company in Japan * Holistic Management International, an American non-profit organization * HornAfrik Media Inc, a media organization based in Mogadishu, Somalia * Hotel Meliá, in Ponce, Puerto Rico * Houston Mechatronics, Inc, see Houston Mechatronics, Inc * Hualien Media International, a global entertainment company in Taipei, Taiwan * Muslim Students' Association (Indonesia) Technology * Helioseismic and Magnetic Imag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
