A generic relation between baryonic and radiative energy densities
... a baryonic or leptonic fluid must kinematically behave like a pure photon fluid in order to have γ = 4/3. Eventually all the above cases correspond to particles having either a degeneracy-related internal Lorentz factor or an ordinary thermal Lorentz factor → ∞. Because this is an extreme idealizati ...
... a baryonic or leptonic fluid must kinematically behave like a pure photon fluid in order to have γ = 4/3. Eventually all the above cases correspond to particles having either a degeneracy-related internal Lorentz factor or an ordinary thermal Lorentz factor → ∞. Because this is an extreme idealizati ...
d = 1 / p
... Expressing this in terms of radius, R = (L / (4π σ T )) . Never confuse the radius of the star R with the distance to the star d! Although both are measures of length that appear in our equations squared and multiplied by 4π, they are extremely different! In addition, keep in mind that the Stefan-Bo ...
... Expressing this in terms of radius, R = (L / (4π σ T )) . Never confuse the radius of the star R with the distance to the star d! Although both are measures of length that appear in our equations squared and multiplied by 4π, they are extremely different! In addition, keep in mind that the Stefan-Bo ...
answers
... 2:34 for a good review and introduction of parallax and standard candles and stop at 2:27. Watch the rest after the light investigations for another 2.5 minutes of Cepheid variable, type 1A super novae. It ends with time and space being connected. Triangulation and Parallax It is best to do this exe ...
... 2:34 for a good review and introduction of parallax and standard candles and stop at 2:27. Watch the rest after the light investigations for another 2.5 minutes of Cepheid variable, type 1A super novae. It ends with time and space being connected. Triangulation and Parallax It is best to do this exe ...
Chapter 28 Stars and Their Characteristics
... • Step 3 - Fusion stops, temperature drops • Step 4 - Core contracts (gravity pulling atoms in) • Step 5 - Increased temperature (more atoms, more collisions) and density in the core reinitiates nuclear fusion, equilibrium is achieved, and the cycle begins again ...
... • Step 3 - Fusion stops, temperature drops • Step 4 - Core contracts (gravity pulling atoms in) • Step 5 - Increased temperature (more atoms, more collisions) and density in the core reinitiates nuclear fusion, equilibrium is achieved, and the cycle begins again ...
The formation of stars and planets
... mass stars (~105), quiet slow star formation, mostly isolated star formation. • Ophiuchus (dist ≈ 140 pc, size ≈ 6 pc, mass ≈ 104 M): Low mass stars (~78), strongly clustered in western core (stellar density 50 stars/pc), high star formation efficiency • Orion (dist ≈ 400 pc, size ≈ 60 pc, mass ≈ 1 ...
... mass stars (~105), quiet slow star formation, mostly isolated star formation. • Ophiuchus (dist ≈ 140 pc, size ≈ 6 pc, mass ≈ 104 M): Low mass stars (~78), strongly clustered in western core (stellar density 50 stars/pc), high star formation efficiency • Orion (dist ≈ 400 pc, size ≈ 60 pc, mass ≈ 1 ...
Multiple Choice, continued
... • If a white dwarf star revolves around a red giant, the gravity of the white dwarf may capture gases from the red giant. • As these gases accumulate on the surface of the white dwarf, pressure begins to build up. • This pressure may cause large explosions, called a ...
... • If a white dwarf star revolves around a red giant, the gravity of the white dwarf may capture gases from the red giant. • As these gases accumulate on the surface of the white dwarf, pressure begins to build up. • This pressure may cause large explosions, called a ...
File
... • If a white dwarf star revolves around a red giant, the gravity of the white dwarf may capture gases from the red giant. • As these gases accumulate on the surface of the white dwarf, pressure begins to build up. • This pressure may cause large explosions, called a ...
... • If a white dwarf star revolves around a red giant, the gravity of the white dwarf may capture gases from the red giant. • As these gases accumulate on the surface of the white dwarf, pressure begins to build up. • This pressure may cause large explosions, called a ...
Wavelength
... outer portion expands • Eventually, the outer parts grow larger and drift out into space creating a planetary nebula. ...
... outer portion expands • Eventually, the outer parts grow larger and drift out into space creating a planetary nebula. ...
Classnotes 9_159 - University of Texas Astronomy
... charge. The proton has one unit of positive charge. The neutron, as its name implies, has no charge. A free (isolated) proton is stable -- experiments have shown that, if it decays, it lives at least 1033 years or so before decaying. A free neutron decays spontaneously in about 11 minutes. A neutro ...
... charge. The proton has one unit of positive charge. The neutron, as its name implies, has no charge. A free (isolated) proton is stable -- experiments have shown that, if it decays, it lives at least 1033 years or so before decaying. A free neutron decays spontaneously in about 11 minutes. A neutro ...
The Interstellar Medium and Star Formation
... • We think planets form from the disks around their host star, shortly after the star forms. As in our Solar System, this probably involves coagulation of small dust grains into pebbles, then rocks, then boulders, then planetesimals, then planets. Some planets become massive enough to also accumulat ...
... • We think planets form from the disks around their host star, shortly after the star forms. As in our Solar System, this probably involves coagulation of small dust grains into pebbles, then rocks, then boulders, then planetesimals, then planets. Some planets become massive enough to also accumulat ...
Return both exam and scantron sheet when you
... 25. Which of these stars spends the longest time as a main sequence star? (a) 0.5 solar mass star. (b) 1 solar mass star. (c) 15 solar mass star. (d) [No statement can be made.] 26. The pressure of degenerate electrons increases with temperature. (a) True. (b) False. 27. Which of these fusion reacti ...
... 25. Which of these stars spends the longest time as a main sequence star? (a) 0.5 solar mass star. (b) 1 solar mass star. (c) 15 solar mass star. (d) [No statement can be made.] 26. The pressure of degenerate electrons increases with temperature. (a) True. (b) False. 27. Which of these fusion reacti ...
Stella Finger Prints
... of matter in space. Throughout their life, stars convert more and more hydrogen to helium, the next simplest form of matter. As the stars age, they burn off their simpler (lighter) elements in a process known as nuclear fusion. Nuclear fusion involves fusing different elements to make simpler (light ...
... of matter in space. Throughout their life, stars convert more and more hydrogen to helium, the next simplest form of matter. As the stars age, they burn off their simpler (lighter) elements in a process known as nuclear fusion. Nuclear fusion involves fusing different elements to make simpler (light ...
1b91: answers to problem sheet no 1
... ζ Puppis is an O4 I star and τ Sco is a B1 V star. State what is meant by these classification terms and give an indication of the surface temperatures of these stars. Stars are classified according to their surface temperatures with the spectral sequence defined as OBAFGKM in order of decreasing te ...
... ζ Puppis is an O4 I star and τ Sco is a B1 V star. State what is meant by these classification terms and give an indication of the surface temperatures of these stars. Stars are classified according to their surface temperatures with the spectral sequence defined as OBAFGKM in order of decreasing te ...
Type II supernova
A Type II supernova (plural: supernovae or supernovas) results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, and no more than 40–50 times, the mass of the Sun (M☉) for this type of explosion. It is distinguished from other types of supernovae by the presence of hydrogen in its spectrum. Type II supernovae are mainly observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies.Stars generate energy by the nuclear fusion of elements. Unlike the Sun, massive stars possess the mass needed to fuse elements that have an atomic mass greater than hydrogen and helium, albeit at increasingly higher temperatures and pressures, causing increasingly shorter stellar life spans. The degeneracy pressure of electrons and the energy generated by these fusion reactions are sufficient to counter the force of gravity and prevent the star from collapsing, maintaining stellar equilibrium. The star fuses increasingly higher mass elements, starting with hydrogen and then helium, progressing up through the periodic table until a core of iron and nickel is produced. Fusion of iron or nickel produces no net energy output, so no further fusion can take place, leaving the nickel-iron core inert. Due to the lack of energy output allowing outward pressure, equilibrium is broken.When the mass of the inert core exceeds the Chandrasekhar limit of about 1.4 M☉, electron degeneracy alone is no longer sufficient to counter gravity and maintain stellar equilibrium. A cataclysmic implosion takes place within seconds, in which the outer core reaches an inward velocity of up to 23% of the speed of light and the inner core reaches temperatures of up to 100 billion kelvin. Neutrons and neutrinos are formed via reversed beta-decay, releasing about 1046 joules (100 foes) in a ten-second burst. The collapse is halted by neutron degeneracy, causing the implosion to rebound and bounce outward. The energy of this expanding shock wave is sufficient to accelerate the surrounding stellar material to escape velocity, forming a supernova explosion, while the shock wave and extremely high temperature and pressure briefly allow for theproduction of elements heavier than iron. Depending on initial size of the star, the remnants of the core form a neutron star or a black hole. Because of the underlying mechanism, the resulting nova is also described as a core-collapse supernova.There exist several categories of Type II supernova explosions, which are categorized based on the resulting light curve—a graph of luminosity versus time—following the explosion. Type II-L supernovae show a steady (linear) decline of the light curve following the explosion, whereas Type II-P display a period of slower decline (a plateau) in their light curve followed by a normal decay. Type Ib and Ic supernovae are a type of core-collapse supernova for a massive star that has shed its outer envelope of hydrogen and (for Type Ic) helium. As a result, they appear to be lacking in these elements.