Section 13 The Stellar Graveyard .


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Section 13 The Stellar Burial ground. Decline "Stars" Cocoa Diminutive people White Midgets Neutron Stars Dark Openings. X-beam picture of supernova remainder G11.2-03, from A.D.386. The Dead 'Stars'. T he End Conditions of Stars Nothing The whole star is scattered into interstellar space,
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Part 13 The Stellar Graveyard Degeneracy "Stars" Brown Dwarfs White Dwarfs Neutron Stars Black Holes X-beam picture of supernova leftover G11.2-03, from A.D.386.

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The Dead "Stars" T he End States of Stars Nothing The whole star is scattered into interstellar space, White dwarfs Remnants of low mass stars ( M < 1.4 M ⊙ ), typical estimate ~ 10 9 cm (about the extent of the Earth). Neutron "stars" Remnants of high-mass stars (1.4 M ⊙ < M < ~3 M ⊙ ), ypical measure ~ 10 6 cm (about the span of a major mountain). Dark holes Stars with mass bigger than ~ 3 M ⊙ will develop into dark holes. Supporting Mechanisms (Force Against Gravity): Regular stars are bolstered by the warm weight produced by the atomic combination forms. White diminutive people and cocoa midgets are both bolstered by the worsen weight of electrons , in spite of the fact that there are distinctive center materials. Neutron stars are bolstered by the decline weight of neutrons . Dark openings is the end condition of an enormous star in which gravitational constriction is strong to the point that it in the long run overpower the decline weight of neutrons.

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Degenerate Stars T hree sorts of "stars" are bolstered by deteriorate weight … Brown Dwarfs Supporting Mechanism Electron decline weight Origin Failed stars Core Composition Electrons, hydrogen cores Mass M bd < 0.08 M sun White Dwarfs Supporting Mechanism: Electron worsen weight Origin Remnants of low and medium mass (M < 8 M sun ) principle grouping stars. Center Composition: Electrons , helium, carbon , and other heavy component cores (from medium-mass stars). Mass 0.08 M sun < M wd < 1.4 M sun Neutron Stars Supporting Mechanism Neutron worsen weight Origin Remnants of high-mass (M > 8 M sun ) fundamental sequence stars. Center Composition Neutrons Mass 1.4 M sun < M neutron < ~ 3 M sun

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White Dwarfs W hite smaller people are remainders of low-mass primary arrangement stars, upheld against gravity by electron deteriorate weight. Contingent upon its underlying mass, the arrangement of the center is distinctive. low-mass stars → helium center low-mass stars → carbon center Medium-mass stars → heavier component centers The nuclear cores in the white smaller people, for example, helium, and carbon, are bosons, not fermions. The rejection standard does not make a difference to bosons, and decline weight does not emerge from these particles. They don\'t battle against gravity! White diminutive person in planetary cloud White midget in globular group M4 Each circle denote a white smaller person. The white midget partner of Sirius

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The Fate of the White Dwarfs T he decline weight DOES NOT rely on upon the temperature of the white diminutive person. A confined white diminutive person, without further collaboration with different stars, will gradually light away its warm vitality into space and chill off, and in the end come into warm harmony with the universe ( extremely frosty ). However … if a white smaller person is not taken off alone, for example, those in close parallel framework, the last phase of the advancement is not really the balance state with the universe. These white smaller people still have an existence after death…

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The Afterlife of White Dwarfs in Close Binary Systems A white diminutive person in a nearby twofold framework can increase significant measure of mass if the sidekick is a primary grouping or mammoth star, giving it another life. In these nearby frameworks, mass from the other star can be exchange to the white diminutive person. The in-falling matter structures a gradual addition plate around the white smaller person. Due to the solid gravity at the surface of the white smaller people, the in-falling velocity is high! The erosion between the gas causes the temperature of the accumulation circle to rise, radiating light in the optical and UV wavelength ranges, Sometimes even X-beam! White diminutive person in X-beam from ROSAT

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Nova T he gas (for the most part hydrogen ) in the growth circle, acquired from the buddy star, may fall into the white midget, gathering at first glance, shaping a shell of hydrogen gas. The temperature and weight develop at first glance bit by bit, in the long run achieving the hydrogen combination temperature of 10 million degrees. Hydrogen shell is touched off and discharge substantial measure of vitality  Nova. This procedure may rehash itself, be that as it may, the recurrence for the event of nova is not entrenched.

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The Chandrasekhar Limit T he recently made helium may gather on the surface of the white diminutive person, expanding its mass. Be that as it may, there is an utmost on the most extreme mass a white smaller person can have… When we increment the mass of the white diminutive person, the electron decadence weight will increments, yet it doesn\'t increment directly and inconclusively, in light of the fact that the speed of the electrons can\'t surpass the speed of the light . This implies there is a furthest point of confinement on the worsen weight the white smaller people can give, and a maximum cutoff on the mass of the white midgets! The Chandrasekhar Limit (or the white smaller person constrain ) is the furthest reaches of the mass of the white midgets: 1.4 M ⊙ . At this mass, the speed of electrons in the white smaller person would be equivalent to the speed of light! Up until this point, NO watched white smaller person have mass bigger than 1.4 M ⊙ , affirming Chandrasekhar\'s hypothesis!

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White Dwarf Supernova E extremely time the hydrogen shell is touched off, the mass of the white smaller person may increment (or reduction, we don\'t know without a doubt yet). The mass of the white diminutive person may step by step increment, At around 1 M ⊙ , t he attractive energy constrain conquers the electron worsen weight, and the white smaller person breakdown, expanding temperature and thickness until it achieves carbon combination temperature . The carbon inside the white midgets are all the while touched off. It detonates to frame a White diminutive person supernova . (Sort I). Nothing is abandoned from a white smaller person supernova blast (as opposed to a gigantic star supernova, which would leave a neutron star or dark gap behind). Every one of the materials are scattered into space. White Dwarf Supernova is a critical standard flame for measuring cosmological separation…

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White Dwarf and Massive Star Supernovae B ecause the mass of white smaller people when they detonate as supernovae is dependably around 1.0 M⊙, its glow is exceptionally predictable, and can be utilized as a standard light for the estimation of separation to inaccessible universes (Chapter 15). The measure of vitality delivered by white midget supernovae and huge star supernovae are about the same. In any case, the properties of the light radiated from these two sorts of supernovae are characteristically unique, permitting us to recognize them from a separation. Monstrous star supernovae range is rich with hydrogen lines (since they have a substantial external layer of hydrogen). White diminutive person supernovae spectra don\'t contain hydrogen line (since white smaller people are for the most part carbon, with just a thin shell of hydrogen). The light bend is distinctive.

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Type I and II Supernovae S upernovae are isolated into to sorts observationally as per the qualities of their spectra. Sort I: Supernovae without solid hydrogen range. Sort I supernovae can be either white diminutive person or huge star supernovae. They are framed from stars that have shed their external hydrogen layer before going supernova. Sort I supernovae are further partitioned into Type Ia, Ib, and Ic, with various light bends. White midget supernovae are Type Ia. Sort II: Supernovae with solid hydrogen lines. All Type II Supernovae are viewed as huge star supernovae in light of the fact that they have a bigger external hydrogen layer.

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Degeneracy "Stars" Brown Dwarfs White Dwarfs Neutron Stars Black Holes

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Neutron Stars T he material science that records for the era of the decadence weight in a neutron star is indistinguishable to that of the decline weight of the electrons in a white diminutive person, since neutrons are fermions . Like as far as possible for the white diminutive people, there is likewise a furthest breaking point on the mass of neutron stars, for the same physical reason. The worsen weight of the neutrons can\'t hold off gravitational compression until the end of time. Be that as it may, its exact esteem has not been precisely decided hypothetically yet, because of deficient learning of atomic material science. The assessed furthest farthest point of the mass of the neutron star is around 3 M ⊙ . Properties of Neutron Stars Size: ~ 10 km . Firmly polarized: ~ 10 9 Gauss (normal on Earth is around 0.5 Gauss) Rapidly turning: ~ 1,000 revolution for each second Very high temperature: ~ 1,000,000 K at first glance

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Neutron Star as a Giant Magnet If the fundamental succession star is an attractive field star, then its attractive fields perhaps caught in the neutron star as the principle arrangement star experiences gravitational crumple. The attractive fields are escalated by a colossal sum, since they are amassed into a considerably littler space. The precise energy of the principle grouping star (or the piece of it that is left) is protected. In view of the neutron star is significantly littler contrasted and the first principle succession star, it will turn at a substantially higher pivot rate (review precise force protection and the turning ice skater). The pivot of the attractive fields may not be adjusted to that of the turn hub (simply like the attractive field of the Earth).

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News: Scientists Measured the Most Powerful Magnet in the Universe RELEASE: 02-156 http://www.gsfc.nasa.gov/topstory/20021030strongestmag.html For activity of a magnetar, allude to: http://nt.phys.gwu.edu/~kovac/magnetar SCIENTISTS MEASURE THE MOST POWERFUL MAGNET KNOWN Scientists have recognized the most attractive question known in the universe, the aftereffect of the main direct estimation of an attractive field around an exceptional neutron star initially watched almost 25 years back. By taking after the destiny of a modest pr

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