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Encyclopedia > Astrophysics
Spiral Galaxy ESO 269-57
Spiral Galaxy ESO 269-57

Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature, and chemical composition) of celestial objects such as stars, galaxies, and the interstellar medium, as well as their interactions. The study of cosmology is theoretical astrophysics at the largest scales. Download high resolution version (750x758, 47 KB)Spiral Galaxy ESO 269-57 This work is copyrighted. ... Download high resolution version (750x758, 47 KB)Spiral Galaxy ESO 269-57 This work is copyrighted. ... Categories: Astronomy stubs | Centaurus constellation | Spiral galaxies ... A giant Hubble mosaic of the Crab Nebula, a supernova remnant. ... Physics (from the Greek, (phúsis), nature and (phusiké), knowledge of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space and time. ... The deepest visible-light image of the cosmos, the Hubble Ultra Deep Field. ... Luminosity has different meanings in several different fields of science. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... Fig. ... Chemistry (from Greek χημεία khemeia[1] meaning alchemy) is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms, such as molecules, crystals, and metals. ... See also Lists of astronomical objects Category: ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... NGC 4414, a typical spiral galaxy in the constellation Coma Berenices, is about 56,000 light years in diameter and approximately 60 million light years distant. ... The distribution of ionized hydrogen (known by astronomers as H II (aitch two) from old spectroscopic terminology) in the parts of the Galactic interstellar medium visible from the Earths northern hemisphere (from the Wisconsin H-Alpha Mapper Survey) In astronomy, the interstellar medium (or ISM) is the matter (interstellar... Cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. ...


Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics. In practice, modern astronomical research involves a substantial amount of physics. The name of a university's department ("astrophysics" or "astronomy") often has to do more with the department's history than with the contents of the programs. Astrophysics can be studied at the bachelors, masters, and Ph.D. levels in aerospace engineering, physics, or astronomy departments at many universities. Mechanics (Greek ) is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. ... Electromagnetism is the force observed as static electricity, and causes the flow of electric charge (electric current) in electrical conductors. ... Statistical mechanics is the application of probability theory, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force. ... Thermodynamics (from the Greek thermos meaning heat and dynamics meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ... Fig. ... In physics, the term relativity is used in several, related contexts: Galileo first developed the principle of relativity, which is the postulate that the laws of physics are the same for all observers. ... Nuclear physics is the branch of physics concerned with the nucleus of the atom. ... Particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... Atomic, molecular, and optical physics is the study of matter-matter and light-matter interactions on the scale of single atoms or structures containing a few atoms. ... The examples and perspective in this article or section may not represent a worldwide view. ... A masters degree is an academic degree usually awarded for completion of a postgraduate (or graduate) course of one to three years in duration. ... This article or section does not cite its references or sources. ... Aerospace engineering is the branch of engineering that concerns aircraft, spacecraft, and related topics. ... Representation of a university class, 1350s. ...

Contents

History

Although astronomy is as ancient as recorded history itself, it was long separated from the study of physics. In the Aristotelian worldview, the celestial world tended towards perfection—bodies in the sky seemed to be perfect spheres moving in perfectly circular orbits—while the earthly world seemed inclined to imperfection; these two realms were not seen as related.


Aristarchus of Samos (c.310-c.250 BC) first put forward the notion that the motions of the celestial bodies could be explained by assuming that the Earth and all the other planets in the Solar System orbited the Sun. Unfortunately, in the geocentric world of the time, Aristarchus' heliocentric theory was deemed outlandish and heretical, and for centuries, the apparently common-sense view that the Sun and other planets went round the Earth went basically unquestioned. Then an astronomer, named Nicolaus Copernicus, revived the heliocentric model in the 16th century. In 1609, Galileo Galilei discovered the four brightest moons of Jupiter, and documented their orbits about that planet, which contradicted the geocentric dogma of the Catholic Church of his time, and escaped serious punishment only by maintaining that his astronomy was a work of mathematics, not of natural philosophy (physics), and therefore purely abstract. Statue of Aristarchus at Aristoteles University in Thessaloniki, Greece Aristarchus (310 BC - c. ... Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Major features of the Solar System (not to scale): The Sun, the eight planets, the asteroid belt containing the dwarf planet Ceres, outermost there is the dwarf planet Pluto (the dwarf planet Eris not shown), and a comet. ... The Sun is the star of our solar system. ... The eight planets and three dwarf planets of the Solar System. ... Earth (IPA: , often referred to as the Earth, Terra, the World or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... Nicolaus Copernicus (February 19, 1473 – May 24, 1543) was an astronomer who provided the first modern formulation of a heliocentric (sun-centered) theory of the solar system in his epochal book, De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres). ... (15th century - 16th century - 17th century - more centuries) As a means of recording the passage of time, the 16th century was that century which lasted from 1501 to 1600. ... Galileo Galilei (February 15, 1564 – January 8, 1642) was an Italian physicist, astronomer, and philosopher who is closely associated with the scientific revolution. ...


The availability of accurate observational data (mainly from the observatory of Tycho Brahe) led to research into theoretical explanations for the observed behavior. At first, only empirical rules were discovered, such as Kepler's laws of planetary motion, discovered at the start of the 17th century. Later that century, Isaac Newton bridged the gap between Kepler's laws and Galileo's dynamics, discovering that the same laws that rule the dynamics of objects on earth rule the motion of planets and the moon. Celestial mechanics, the application of Newtonian gravity and Newton's laws to explain Kepler's laws of planetary motion, was the first unification of astronomy and physics. Tycho Brahe Monument of Tycho Brahe and Johannes Kepler in Prague   , born Tyge Ottesen Brahe (December 14, 1546 – October 24, 1601), was a Danish (Scanian) nobleman best known today as an early astronomer, though in his lifetime he was also well known as an astrologer and alchemist. ... Empirical is an adjective often used in conjunction with science, both the natural and social sciences, which means an observation or experiment based upon experience that is capable of being verified or disproved. ... This article does not cite its references or sources. ... (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... Sir Isaac Newton, FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, alchemist, and natural philosopher, regarded by many as the greatest figure in the history of science. ... Celestial mechanics is a division of astronomy dealing with the motions and gravitational effects of celestial objects. ... Gravity is a force of attraction that acts between bodies that have mass. ...


After Isaac Newton published his book, Philosophiae Naturalis Principia Mathematica, maritime navigation was transformed. Starting around 1670, the entire world was measured using essentially modern latitude instruments and the best available clocks. The needs of navigation provided a drive for progressively more accurate astronomical observations and instruments, providing a background for ever more available data for scientists. Newtons own copy of his Principia, with hand written corrections for the second edition. ... Table of geography, hydrography, and navigation, from the 1728 Cyclopaedia. ... 1670 was a common year beginning on a Saturday in countries using the Julian calendar and a Wednesday in countries using the Gregorian calendar. ... Latitude, usually denoted symbolically by the Greek letter φ, gives the location of a place on Earth north or south of the Equator. ... A clock (from the Latin cloca, bell) is an instrument for measuring time. ...


At the end of the 19th century, it was discovered that, when decomposing the light from the Sun, a multitude of spectral lines were observed (regions where there was less or no light). Experiments with hot gases showed that the same lines could be observed in the spectra of gases, specific lines corresponding to unique chemical elements. In this way it was proved that the chemical elements found in the Sun(chiefly hydrogen) were also found on Earth. Indeed, the element helium was first discovered in the spectrum of the sun and only later on earth, hence its name. During the 20th century, spectroscopy (the study of these spectral lines) advanced, particularly as a result of the advent of quantum physics that was necessary to understand the astronomical and experimental observations.[1] Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... The Sun is the star of our solar system. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... The periodic table of the chemical elements A chemical element, often called simply an element, is a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Etymology is the study of the origins of words. ... (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999... Extremely high resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines) Spectroscopy is the study of matter by investigating light, sound, or particles that are emitted, absorbed or scattered by the matter under investigation. ... Fig. ...


See also:

Timeline of galaxies, clusters of galaxies, and large-scale structure of the cosmos 964 - Al Sufi, a Persian astronomer makes the first preserved recording of the Large Magellanic Cloud. ... Timeline of white dwarfs, neutron stars, and supernovae Note that this list is mainly about the development of knowledge, but also about some supernovae taking place. ... Timeline of black hole physics 1640 - Ismael Bullialdus suggests an inverse-square gravitational force law 1684 - Isaac Newton writes down his inverse-square Law of universal gravitation 1758 - Rudjer Josip Boscovich developes his Theory of forces, where gravity can be repulsive on small distances. ... Timeline of gravitational physics and relativity 1583 - Galileo Galilei induces the period relationship of a pendulum from observation (according to later biographer). ...

Observational astrophysics

Most astrophysical processes cannot be reproduced in laboratories on Earth. However, there is a huge variety of astronomical objects visible all over the electromagnetic spectrum. The study of these objects through passive collection of data is the goal of observational astrophysics.


The equipment and techniques required to study an astrophysical phenomenon can vary widely. Many astrophysical phenomena that are of current interest can only be studied by using very advanced technology and were simply not known until very recently.


The majority of astrophysical observations are made using the electromagnetic spectrum. Legend: γ = Gamma rays HX = Hard X-rays SX = Soft X-Rays EUV = Extreme ultraviolet NUV = Near ultraviolet Visible light NIR = Near infrared MIR = Moderate infrared FIR = Far infrared Radio waves: EHF = Extremely high frequency (Microwaves) SHF = Super high frequency (Microwaves) UHF = Ultra high frequency VHF = Very high frequency HF = High...

Other than electromagnetic radiation, few things may be observed from the Earth that originate from great distances. A few gravitational wave observatories have been constructed, but gravitational waves are extremely difficult to detect. Neutrino observatories have also been built, primarily to study our Sun. Cosmic rays consisting of very high energy particles can be observed hitting the Earth's atmosphere. Microwave image of 3C353 galaxy at 8. ... The wavelength is the distance between repeating units of a wave pattern. ... In cosmology, the cosmic microwave background radiation (most often abbreviated CMB but occasionally CMBR, CBR or MBR, also referred as relic radiation) is a form of electromagnetic radiation discovered in 1965 that fills the entire universe. ... Redshift of spectral lines in the optical spectrum of a supercluster of distant galaxies (right), as compared to that of the Sun (left). ... According to the Big Bang, the universe emerged from an extremely dense and hot state (bottom). ... Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsars magnetic field and radiation. ... The 64 metre radio telescope at Parkes Observatory The Very Large Array, an interferometric array formed from many smaller telescopes, like many larger radio telescopes. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... 50 cm refracting telescope at Nice Observatory. ... See also list of optical topics. ... Optical astronomy encompasses a wide variety of observations via telescopes that are sensitive in the range of visible light. ... 50 cm refracting telescope at Nice Observatory. ... A specially developed CCD used for ultraviolet imaging in a wire bonded package. ... A spectroscope is a device which measures the spectrum of light. ... A deformable mirror can be used to correct wavefront errors in an astronomical telescope. ... A space observatory is any object in outer space which is used for observation of distant planets, galaxies, and other outer space objects. ... The Triangulum Emission Nebula NGC 604 lies in a spiral arm of Galaxy M33, 2. ... Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays. ... ROSAT image of X-ray fluorescence of, and occultation of the X-ray background by, the Moon. ... Gamma-ray astronomy is the astronomical study of gamma rays. ... A binary pulsar is a pulsar with a binary companion, often another pulsar, white dwarf or neutron star. ... A black hole is an object predicted by general relativity[1] with a gravitational field so strong that nothing can escape it — not even light. ... Artists conception of a magnetar, with magnetic field lines A magnetar is a neutron star with an extremely strong magnetic field, the decay of which powers the emission of copious amounts of high-energy electromagnetic radiation, particularly X-rays and gamma-rays. ... The Rossi X-ray Timing Explorer (RXTE) satellite observes the fast-moving, high-energy worlds of black holes, neutron stars, X-ray pulsars and bursts of X-rays that light up the sky and then disappear forever. ... For other uses, see Chandra (disambiguation). ... Illustration of CGRO The Compton Gamma Ray Observatory(CGRO) was the second of the NASA Great Observatories to be launched to space, following the Hubble Space Telescope. ... In physics, gravitational radiation is energy that is transmitted through waves in the gravitational field of space-time, according to Albert Einsteins theory of general relativity: The Einstein field equations imply that any accelerated mass radiates energy this way, in the same way as the Maxwell equations that any... The neutrino is an elementary particle. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ...


Observations can also vary in their time scale. Most optical observations take minutes to hours, so phenomena that change faster than this cannot readily be observed. However, historical data on some objects is available spanning centuries or millennia. On the other hand, radio observations may look at events on a millisecond timescale (millisecond pulsars) or combine years of data (pulsar deceleration studies). The information obtained from these different timescales is very different. A millisecond pulsar (MSP), often referred to as recycled pulsar, is a pulsar with a rotational period in the range of about 1-10 milliseconds. ... Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsars magnetic field and radiation. ...


The study of our own Sun has a special place in observational astrophysics. Due to the tremendous distance of all other stars, the Sun can be observed in a kind of detail unparalleled by any other star. Our understanding of our own sun serves as a guide to our understanding of other stars.


The topic of how stars change, or stellar evolution, is often modelled by placing the varieties of star types in their respective positions on the Hertzsprung-Russell diagram, which can be viewed as representing the state of a stellar object, from birth to destruction. The material composition of the astronomical objects can often be examined using: In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat. ... The Hertzsprung-Russell diagram (usually referred to by the abbreviation H-R diagram or HRD, also known as a Colour-Magnitude (CM) diagram) shows the relationship between absolute magnitude, luminosity, classification, and surface temperature of stars. ...

Extremely high resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines) Spectroscopy is the study of matter by investigating light, sound, or particles that are emitted, absorbed or scattered by the matter under investigation. ... Microwave image of 3C353 galaxy at 8. ... Neutrino astronomy is the science of observing astronomical phenomena by detecting neutrinos, a product of thermonuclear reactions going on inside every star. ...

Theoretical astrophysics

Theoretical astrophysics is the discipline that seeks to explain the phenomena observed by astronomers in physical terms with a theoretic approach. With this purpose, theoretical astrophysicists create and evaluate models and physical theories to reproduce and predict the observations. In most cases, trying to figure out the implications of physical models is not easy and takes a lot of time and effort. An astronomer or astrophysicist is a person whose area of interest is astronomy or astrophysics. ... An astrophysicist is a person whose profession is astrophysics. ...


Theoretical astrophysicists use a wide variety of tools which include analytical models (for example, polytropes to approximate the behaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of a process are generally better for giving insight into the heart of what is going on. Numerical models can reveal the existence of phenomena and effects that would otherwise not be seen.[2][3] A polytrope is a solution to the Lane-Emden equation. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Numerical analysis is the study of approximate methods for the problems of continuous mathematics (as distinguished from discrete mathematics). ...


Theorists in astrophysics endeavor to create theoretical models and figure out the observational consequences of those models. This helps allow observers to look for data that can refute a model or help in choosing between several alternate or conflicting models.


Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, the general tendency is to try to make minimal modifications to the model to fit the data. In some cases, a large amount of inconsistent data over time may lead to total abandonment of a model.


Within the astronomical community, theorists are widely caricatured as being mechanically inept and unlucky for observational efforts. Having a theorist at an observatory is considered likely to jinx an observation run and cause machines to break inexplicably or to have the sky cloud over.


Topics studied by theoretical astrophysicists include: stellar dynamics and evolution; galaxy formation; large-scale structure of matter in the Universe; origin of cosmic rays; general relativity and physical cosmology, including string cosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scale structures for which gravitation plays a significant role in physical phenomena investigated and serves as the basis for black hole (astro)physics and the study of gravitational waves. Stellar dynamics is the branch of astrophysics which describes in a statistical way the collective motions of stars subject to their mutual gravity. ... In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat. ... REDIRECT [[ --68. ... In physics, matter is commonly defined as the substance of which physical objects are composed, not counting the contribution of various energy or force-fields, which are not usually considered to be matter per se (though they may contribute to the mass of objects). ... The deepest visible-light image of the cosmos, the Hubble Ultra Deep Field. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. ... Cosmology, as a branch of astrophysics, is the study of the large-scale structure of the universe and is concerned with fundamental questions about its formation and evolution. ... Interaction in the subatomic world: world lines of pointlike particles in the Standard Model or a world sheet swept up by closed strings in string theory String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles... Particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... A black hole is an object predicted by general relativity[1] with a gravitational field so strong that nothing can escape it — not even light. ... Physics (from the Greek, (phúsis), nature and (phusiké), knowledge of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space and time. ... In physics, gravitational radiation is energy that is transmitted through waves in the gravitational field of space-time, according to Albert Einsteins theory of general relativity: The Einstein field equations imply that any accelerated mass radiates energy this way, in the same way as the Maxwell equations that any...


Some widely accepted and studied theories and models in astrophysics, now included in the Lambda-CDM model are the Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics. A pie chart indicating the proportional composition of different energy-density components of the universe. ... According to the Big Bang, the universe emerged from an extremely dense and hot state (bottom). ... Cosmic inflation is the idea, first proposed by Alan Guth in 1981, that the nascent universe passed through a phase of exponential expansion (the inflationary epoch) that was driven by a negative pressure vacuum energy density. ... In astrophysics, dark matter is matter that does not emit or reflect enough electromagnetic radiation (such as light, X-rays and so on) to be detected directly, but whose presence may be inferred from its gravitational effects on visible matter. ... Physics (from the Greek, (phúsis), nature and (phusiké), knowledge of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space and time. ...


A few examples of this process:

Physical process Experimental tool Theoretical model Explains/predicts
Gravitation Radio telescopes Self-gravitating system Emergence of a star system
Nuclear fusion Spectroscopy Stellar evolution How the stars shine and how metals formed
The Big Bang Hubble Space Telescope, COBE Expanding universe Age of the Universe
Quantum fluctuations Cosmic inflation Flatness problem
Gravitational collapse X-ray astronomy General relativity Black holes at the center of Andromeda galaxy
CNO cycle in stars

Dark matter and dark energy are the current leading topics in astrophysics, as their discovery and controversy originated during the study of the galaxies. Gravity or Gravitation is a property by which all objects attract each other. ... The 64 metre radio telescope at Parkes Observatory The Very Large Array, an interferometric array formed from many smaller telescopes, like many larger radio telescopes. ... In theoretical astrophysics, the Nordtvedt Effect refers to the relative motion between the Earth and the Moon which would be observed if the graviational self-energy of a body contributes to its gravitational mass but not its inertial mass. ... A star system or stellar system is a system comprised of a star or group of stars, and, perhaps, planetary systems of smaller bodies (such as planets or asteroids), in gravitational association. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Extremely high resolution spectrum of the Sun showing thousands of elemental absorption lines (fraunhofer lines) Spectroscopy is the study of matter by investigating light, sound, or particles that are emitted, absorbed or scattered by the matter under investigation. ... In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat. ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ... According to the Big Bang theory, the universe originated in an infinitely dense and physically paradoxical singularity. ... The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble for his discovery of galaxies outside the Milky Way and his creation of Hubbles Law, which calculates the rate at which the universe is expanding. ... The Cosmic Background Explorer (COBE), also referred to as Explorer 66, was the first satellite built dedicated to cosmology. ... Accelerating universe is a term for the idea that our universe is undergoing divergent rapid expansion. ... The age of the universe, according to the Big Bang theory, is defined as the largest possible value of proper time integrated along a time-like curve from the Earth at the present epoch back to the Big Bang. The time that has elapsed on a hypothetical clock which has... In quantum physics, a quantum fluctuation is the temporary change in the amount of energy in a point in space, arising from Werner Heisenbergs uncertainty principle. ... Cosmic inflation is the idea, first proposed by Alan Guth in 1981, that the nascent universe passed through a phase of exponential expansion (the inflationary epoch) that was driven by a negative pressure vacuum energy density. ... The flatness problem is a cosmological problem with the Big Bang theory, which is solved by hypothesising an inflationary universe. ... This article or section does not cite its references or sources. ... ROSAT image of X-ray fluorescence of, and occultation of the X-ray background by, the Moon. ... General relativity (GR) is the geometrical theory of gravitation published by Albert Einstein in 1915. ... A black hole is an object predicted by general relativity[1] with a gravitational field so strong that nothing can escape it — not even light. ... This article does not cite its references or sources. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... In astrophysics, dark matter is matter that does not emit or reflect enough electromagnetic radiation (such as light, X-rays and so on) to be detected directly, but whose presence may be inferred from its gravitational effects on visible matter. ... In physical cosmology, dark energy is a hypothetical form of energy which permeates all of space and has strong negative pressure. ...


See also

Physics Portal
Wikibooks
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Astrophysics

Image File history File links Portal. ... Image File history File links Wikibooks-logo-en. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is part of the Wikimedia Foundation. ... The following is a list of astronomical observatories, along with initial dates of operation and location, if available. ... This is a list of important publications in physics, organized by field. ... An astrophysicist is a person whose profession is astrophysics. ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ... A 1960s single stage 2 MeV linear Van de Graaff accelerator, here opened for maintenance A particle accelerator is a device that uses electric fields to propel electrically charged particles to high speeds and magnetic fields to contain them. ... Astrodynamics is the study of the motion of rockets, missiles, and space vehicles, as determined from Sir Isaac Newtons laws of motion and his law of universal gravitation. ...

References

  1. ^ Frontiers of Astrophysics: Workshop Summary, H. Falcke, P. L. Biermann
  2. ^ H. Roth, A Slowly Contracting or Expanding Fluid Sphere and its Stability, Phys. Rev. (39, p;525–529, 1932)
  3. ^ A.S. Eddington, Internal Constitution of the Stars

External links

  • Prof. Sir Harry Kroto, NL, Astrophysical Chemistry Lecture Series. 8 Freeview Lectures provided by the Vega Science Trust.
  • 'The Mathematician Who Can't Add Up' Cosmologist Emma King Freeview 'Snapshots video' by the Vega Science Trust.
  • Stanford Linear Accelerator Center, Stanford, California
 v  d  e 
General subfields within astronomy
Astrophysics • Cosmology • Galactic astronomy • Extragalactic astronomy • Galaxy formation and evolution • Planetary science • Stellar astronomy • Stellar evolution • Star formation
Physics Portal

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