Black Holes - Level 1

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Black Holes - Level 1Replay the animationBlack HolesIntroduction to Black HolesBlack holes are objects so dense that not even light can escape their gravity, and since nothing can travelfaster than light, nothing can escape from inside a black hole. On the other hand, a black hole exerts thesame force on something far away from it as any other object of the same mass would. For example, if ourSun was magically crushed until it was about 1 mile in size, it would become a black hole, but the Earthwould remain in its same orbit.Even back in Isaac Newton's time, scientists speculated that such objects could exist, even though we nowknow they are more accurately described using Einstein's General Theory of Relativity. Using this theory,black holes are fascinating objects where space and time become so warped that time practically stops inthe vicinity of a black hole.Contrary to popular belief, there is a great deal of observational evidence for the existence of two types ofblack holes; those with masses of a typical star, and those with masses of a typical galaxy.The former type have measured masses ranging from 4 to 15 Suns, and are believed to be formed duringsupernova explosions. The after-effects are observed in some X-ray binaries known as black holecandidates.On the other hand, galaxy-mass black holes are found in Active Galactic Nuclei (AGN). These are thoughtto have the mass of about 10 to 100 billion Suns. The mass of one of these supermassive black holes hasrecently been measured using radio astronomy. X-ray observations of iron in the accretion disks mayactually be showing the effects of such a massive black hole as w l1/black holes.html (1 of 2) [5/26/1999 11:24:16 AM]

Black Holes - Level 1Journey into a Black HoleSee an animation of the suspected black hole at the heart of the galaxy M87. You will need the appropriatesoftware and drivers to view it.AVI format (1.6 Mb)QuickTime format (1.4 Mb)"Quiz Me!" aboutthis topic!Imagine!HomepageImagine!FeedbackCool Fact about thistopic!Ask aNASAScientistImagineScience!Show Me relatedlesson plans!Satellites& DataOtherGoodResourcesGive Me naryImagine the Universe! is a service of the High Energy Astrophysics Science Archive Research Center(HEASARC), Dr. Nicholas E. White (Director), within the Laboratory for High Energy Astrophysics(LHEA) at NASA/ GSFC.Website Text Authors: The Imagine! TeamProject Leader: Dr. Laura WhitlockTechnical Rep: Sherri CalvoComments or Feedback about our site can be sent to: ideas@heasarc.gsfc.nasa.gov. Science-relatedquestions should be directed to Ask a NASA Scientist .http://imagine.gsfc.nasa.gov/docs/science/know l1/black holes.html (2 of 2) [5/26/1999 11:24:16 AM]

Black Holes - StandardsBlack HolesInformation/Activities on this page relate toNCTM Curriculum and EvaluationStandards:Information/Activities on this page relate toNational Science Education Standards: None A(5-12): Science as InquiryD(9-12): Origin/Evolution of the UniverseG(5-12): History & Nature of ScienceTake me to a complete listing of the mathematics standards.Take me to a complete listing of the science standards.Close this window to return to the previous ndards/black holes.html [5/26/1999 11:24:21 AM]

Imagine the Universe! DictionaryImagine the Universe!DictionaryPlease allow the whole page to load before you start searching for an entry. Otherwise, errors will occur.[A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ]AaccretionAccumulation of dust and gas into larger bodies such as stars, planets and moons.accretion diskA relatively flat sheet of gas and dust surrounding a newborn star, a black hole, or any massive objectgrowing in size by attracting material.active galactic nuclei (AGN)It is believed that these are normal galaxies with a massive black hole accreting gas at its center, thusproducing enormous amounts of energy at all wavelengths of the electromagnetic spectrum.Tell me about AGN!Tell me more about AGN!angstromA unit of length equal to 0.00000001 centimeters. Scientists sometimes write this as 1 x 10-8 cm (seescientific notation).angular momentumA quantity obtained by multiplying the mass of an orbiting body by its velocity and the radius of its orbit.According to the conservation laws of physics, the angular momentum of any orbiting body must remainconstant at all points in the orbit, i.e., it cannot be created or destroyed. If the orbit is elliptical the radiuswill vary. Since the mass is constant, the velocity changes. Thus planets in elliptical orbits travel faster atperiastron and more slowly at apastron. A spinning body also possesses spin angular momentum.apoapsisThe point in an orbit when the two objects are farthest apart. Special names are given to this orbital pointfor commonly used systems. For example, the point of greatest separation of two stars, as in a binary starorbit, is called apastron; the point in its orbit where a planet is farthest from the Sun is called aphelion; thepoint in its orbit where an Earth satellite is farthest from the Earth is called apogee.Ariel Vhttp://imagine.gsfc.nasa.gov/docs/dictionary.html (1 of 28) [5/26/1999 11:24:49 AM]

Imagine the Universe! DictionaryA UK X-ray mission, also known as UK-5Tell me more about Ariel VASCAThe Japanese Asuka spacecraft (formerly Astro-D)Tell me more about ASCAASMAll Sky Monitor. Many high-energy satellites have carried ASM detectors, including the ASM on Vela5B, Ariel V, and the Rossi X-ray Timing Explorer.Astro EA new X-ray/gamma-ray mission being built jointly by the United States and Japan. Astro E currently hasan estimated launch date of the year 2000.Tell me more about Astro Eastronomical unit (AU)149,597,870 km; the average distance from the Earth to the Sun.astronomyThe scientific study of matter in outer space, especially the positions, dimensions, distribution, motion,composition, energy, and evolution of celestial bodies and phenomena.astrophysicsThe part of astronomy that deals principally with the physics of stars, stellar systems, and interstellarmaterial.atmosphereThe gas that surrounds a planet or star. The Earth's atmosphere is made up of mostly nitrogen, while theSun's atmosphere consists of mostly hydrogen.AXAFThe Advanced X-ray Astrophysics Facility. AXAF is currently scheduled to be launched by the SpaceShuttle in August, 1998.Tell me more about AXAFBBalmer lines (J. Balmer)Emission or absorption lines in the spectrum of hydrogen that arise from transitions between the second(or first excited) state and higher energy states of the hydrogen atom.BBXRTBroad Band X-Ray Telescope on Astro-1 shuttle flight (Dec. 1990)Tell me more about html (2 of 28) [5/26/1999 11:24:49 AM]

Imagine the Universe! Dictionarybinary starsBinary stars are two stars that orbit around a common center of mass. An X-ray binary is a special casewhere one of the stars is a collapsed object such as a white dwarf, neutron star, or black hole. Matter isstripped from the normal star and falls onto the collapsed star, producing X-rays.Tell me about X-ray binary starsTell me more about X-ray binary starsblack holeAn object whose gravity is so strong that not even light can escape from it.Tell me about X-rays from black holesTell me about gamma-rays from black holes and neutron starsTell me more about black holesblack-hole dynamic laws; laws of black-hole dynamics1. First law of black hole dynamics:For interactions between black holes and normal matter, the conservation laws of mass-energy,electric charge, linear momentum, and angular momentum, hold. This is analogous to the first lawof thermodynamics.2. Second law of black hole dynamics:With black-hole interactions, or interactions between black holes and normal matter, the sum of thesurface areas of all black holes involved can never decrease. This is analogous to the second law ofthermodynamics, with the surface areas of the black holes being a measure of the entropy of thesystem.blackbody radiationThe radiation -- the radiance at particular frequencies all across the spectrum -- produced by a blackbody -that is, a perfect radiator (and absorber) of heat. Physicists had difficulty explaining it until Planckintroduced his quantum of action.blackbody temperatureThe temperature of an object if it is re-radiating all the thermal energy that has been added to it; if anobject is not a blackbody radiator, it will not re-radiate all the excess heat and the leftover will go towardincreasing its temperature.blueshiftAn apparent shift toward shorter wavelengths of spectral lines in the radiation emitted by an object causedby the emitting object moving toward the observer. See also Doppler effect.Boltzmann constant; k (L. Boltzmann)A constant which describes the relationship between temperature and kinetic energy for molecules in anideal gas. It is equal to 1.380622 x 10-23 J/K (see scientific notation).Brahe, Tycho 1546 - 1601(a.k.a Tyge Ottesen) Danish astronomer whose accurate astronomical observations formed the basis forJohannes Kepler's laws of planetary motion. (132 k tml (3 of 28) [5/26/1999 11:24:50 AM]

Imagine the Universe! Dictionarybremsstrahlung"braking radiation", the main way very fast charged particles lose energy when traveling through matter.Radiation is emitted when charged particles are accelerated. In this case, the acceleration is caused by theelectromagnetic fields of the atomic nuclei of the medium.CcalibrationA process for translating the signals produced by a measuring instrument (such as a telescope) intosomething that is scientifically useful. This procedure removes most of the errors caused by environmentaland instrumental instabilities.CGROThe Compton Gamma Ray ObservatoryTell me more about CGROChandrasekhar limit (S. Chandrasekhar; 1910 - 1995)A limit which mandates that no white dwarf (a collapsed, degenerate star) can be more massive than about1.4 solar masses. Any degenerate object more massive must inevitably collapse into a neutron star.cluster of galaxiesA system of galaxies containing from a few to a few thousand member galaxies which are allgravitationally bound to each other.collecting areaThe amount of area a telescope has that is capable of collecting electromagnetic radiation. Collecting areais important for a telescope's sensitivity: the more radiation it can collect (that is, the larger its collectingarea), the more sensitive it is to dim objects.Compton effect (A.H. Compton; 1923)An effect that demonstrates that photons (the quantum of electromagnetic radiation) have momentum. Aphoton fired at a stationary particle, such as an electron, will impart momentum to the electron and, sinceits energy has been decreased, will experience a corresponding decrease in frequency.Tell me how gamma-ray astronomers use the Compton effectCopernicusNASA ultraviolet/X-ray mission, also known as OAO-3Tell me more about CopernicusCopernicus, Nicolaus 1473 - 1543Polish astronomer who advanced the heliocentric theory that the Earth and other planets revolve aroundthe Sun. This was highly controversial at the time as the Ptolemaic view of the universe, which was theprevailing theory for over 1000 years, was deeply ingrained in the prevailing philosophy and religion. (Itshould be noted, however, that the heliocentric idea was first put forth by Aristarcus of Samos in the 3rdcentury B.C., a fact known to Copernicus but long ignored.) (125 k GIF).corona (plural: ry.html (4 of 28) [5/26/1999 11:24:50 AM]

Imagine the Universe! DictionaryThe uppermost level of the solar atmosphere, characterized by low densities and high temperatures ( 1,000,000 degrees K).Tell me about X-rays from the Sun's coronaTell me about X-rays from other stellar coronaeCOS-BA satellite launched in August 1975 to study extraterrestrial sources of gamma-ray emission.Tell me more about COS-Bcosmic background radiation; primal glowThe background of radiation mostly in the frequency range 3 x 108 to 3 x 1011 Hz (see scientific notation)discovered in space in 1965. It is believed to be the cosmologically redshifted radiation released by the BigBang itself.cosmic raysAtomic nuclei (mostly protons) and electrons that are observed to strike the Earth's atmosphere withexceedingly high energies.cosmological constant; LambdaThe constant introduced to the Einstein field equation, intended to admit static cosmological solutions. Atthe time the current philosophical view was the steady-state model of the Universe, where the Universehas been around for infinite time. Early analysis of the field equation indicated that general relativityallowed dynamic cosmological models only (ones that are either contracting or expanding), but no staticmodels. Einstein introduced the most natural aberration to the field equation that he could think of: theaddition of a term proportional to the spacetime metric tensor, g, with the constant of proportionality beingthe cosmological constant:G Lambda g 8 pi T.Hubble's later discovery of the expansion of the Universe indicated that the introduction of thecosmological constant was unnecessary; had Einstein believed what his field equation was telling him, hecould have claimed the expansion of the Universe as perhaps the greatest and most convincing predictionof general relativity; he called this the "greatest blunder of my life."cosmological distanceA distance far beyond the boundaries of our Galaxy. When viewing objects at cosmological distances, thecurved nature of spacetime could become apparent. Possible cosmological effects include time dilationand redshift.cosmological redshiftAn effect where light emitted from a distant source appears redshifted because of the expansion ofspacetime itself. Compare Doppler effect.cosmologyThe astrophysical study of the history, structure, and constituent dynamics of the ary.html (5 of 28) [5/26/1999 11:24:50 AM]

Imagine the Universe! DictionaryDde Broglie wavelength (L. de Broglie; 1924)According to quantum mechanics all particles also have wave characteristics, where the wavelength of aparticle is inversely proportional to its momentum and the constant of proportionality is the Planckconstant.DeclinationA coordinate which, along with Right Ascension, may be used to locate any position in the sky.Declination is analogous to latitude for locating positions on the Earth.deconvolutionAn image processing technique that removes features in an image that are caused by the telescope itselfrather than from actual light coming from the sky.densityThe amount of mass of any substance which can be contained in one cubic centimeter. Measured in gramsper cubic centimeter (or kilograms per liter); the density of water is 1.0; iron is 7.9; lead is 11.3.disk (of planet or other object)The apparent circular shape that the Sun, a planet, or a moon displays when seen in the sky or through atelescope.Doppler effect (C.J. Doppler)The apparent change in wavelength of sound or light caused by the motion of the source, observer or both.Waves emitted by a moving object as received by an observer will be blueshifted (compressed) ifapproaching, redshifted (elongated) if receding. It occurs both in sound and light. How much thefrequency changes depends on how fast the object is moving toward or away from the receiver. Comparecosmological redshift.EeccentricNon-circular; elliptical (applied to an orbit).eccentricityA value that defines the shape of an ellipse or planetary orbit. The eccentricity of an ellipse (planetaryorbit) is the ratio of the distance between the foci and the major axis. Equivalently the eccentricity is(ra-rp)/(ra rp) where ra is the apoapsis distance and rp is the periapsis distance.eclipseThe cutting off, or blocking, of light from one celestial body by another.eclipticThe plane of Earth's orbit about the SunEddington limit (Sir A. Eddington)The theoretical limit at which the photon pressure would exceed the gravitational attraction of ahttp://imagine.gsfc.nasa.gov/docs/dictionary.html (6 of 28) [5/26/1999 11:24:50 AM]

Imagine the Universe! Dictionarylight-emitting body. That is, a body emitting radiation at greater than the Eddington limit would break upfrom its own photon pressure.Einstein, Albert 1879 - 1955German-American physicist; developed the Special and General Theories of Relativity which along withQuantum Mechanics is the foundation of modern physics. (32 k GIF)ejectaMaterial that is ejected. Used mostly to describe the content of a massive star that is propelled outward in asupernova explosion.electromagnetic spectrumThe full range of frequencies, from radio waves to gamma-rays, that characterizes light.Introduce me to the electromagnetic spectrumTell me more about the electromagnetic spectrumelectromagnetic waves (radiation)Another term for light. Light waves are fluctuations of electric and magnetic fields in space.electronA particle commonly found in the outer layers of atoms with a negative charge. The electron has only0.0005 the mass of the proton.electron voltThe change of potential energy experienced by an electron moving from a place where the potential has avalue of V to a place where it has a value of (V 1 volt). This is a convenient energy unit when dealingwith the motions of electrons and ions in electric fields; the unit is also the one used to describe the energyof X-rays and gamma-rays. A keV (or kiloelectron volt) is equal to 1000 electron volts. An MeV is equalto one million electron volts. A GeV is equal to one billion (109) electron volts. A TeV is equal to amillion million (1012) electron volts.elementsThe fundamental kinds of atoms that make up the building blocks of matter, which are each shown on theperiodic table of the elements. The most abundant elements in the universe are hydrogen and helium.These two elements make up about 80and 20 % of all the matter in the universe respectively. Despitecomprising only a very small fraction the universe, the remaining heavy elements can greatly influenceastronomical phenomena. About 2 % of the Milky Way's disk is comprised of heavy elements.ellipseOval. That the orbits of the planets are ellipses, not circles, was first discovered by Johannes Kepler basedon the careful observations by Tycho Brahe.erg/secA form of the metric unit for power. It is equal to 10-10 kilowatts (see scientific notation).event horizonThe radius that a spherical mass must be compressed to in order to transform it into a black hole, or theradius at which time and space switch responsibilities. Once inside the event horizon, it is tionary.html (7 of 28) [5/26/1999 11:24:50 AM]

Imagine the Universe! Dictionaryimpossible to escape to the outside. Furthermore, nothing can prevent a particle from hitting the singularityin a very short amount of proper time once it has entered the horizon. In this sense, the event horizon is a"point of no return". See Schwarzschild radius.evolved starA star near the end of its lifetime when most of its fuel has been used up. This period of the star's life ischaracterized by loss of mass from its surface in the form of a stellar wind.EXOSATEuropean Space Agency's X-ray ObservatoryTell me more about EXOSATextragalacticOutside of, or beyond, our own galaxy.FFast Fourier Transformation (FFT)A Fourier Transform is the mathematical operation that takes measurements made with a radiointerferometer and transforms them into an image of the radio sky. The Fast Fourier Transform istechnique used by computer programs that allows the Fourier Transform to be computed very quickly.Fermi accelerationIn order to explain the origins of cosmic rays, Enrico Fermi (1949) introduced a mechanism of particleacceleration,

black holes are fascinating objects where space and time become so warped that time practically stops in the vicinity of a black hole. Contrary to popular belief, there is a great deal of observational evidence for the existence of two types of black holes; those with masses of a typical star, and those with masses of a typical galaxy. The former type have measured masses ranging from 4 to 15 .

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mass black holes, no credible formation process is known, and indeed no indications have been found that black holes much lighter than this \Chandrasekhar limit" exist anywhere in the Universe. Does this mean that much lighter black holes cannot exist? It is here that one could wonder about all those fundamental assumptions that underly the theory of quantum mechanics, which is the basic .

However, in addition to black holes formed by stellar collapse, there might also be much smaller black holes which were formed by density fluctua-202 S. W. Hawking tions in the early universe [9, 10]. These small black holes, being at a higher temperature, would radiate more than they absorbed. They would therefore pre- sumably decrease in mass. As they got smaller, they would get hotter and .

Black holes have entropy S. Black holes have Hawking temperature T H, consistent with thermodynamic relation between energy, entropy and temperature. Thermodynamics S A 4 where Ais the area of the event horizon. T H 2 ˇ where in the surface gravity of the black hole. Luke Barclay Durham, CPT luke.barclay@durham.ac.uk Supervisor: Ruth GregoryBlack Holes, Vortices and Thermodynamics. Path .

Sep 27, 2015 · Beams - Straight Beams are measured by counting the number of holes. Beams come in odd numbers when counting the holes, with one exception. Beams start with15 holes and go down in size by two holes to the 3 hole beam and include one even-numbered beam with 2 holes. The number of holes corresponds to the length

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Session 10 – Black Holes. Brief Description. Students learn about black holes, the densest objects in the Universe. They learn that the collapsing . core of a star forms a black hole and do an activity that shows how the density of a stellar core increases as the core collapses even though the mass remains the same. They then engage in a kinesthetic activity to model how a black hole affects .

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