Galaxies and the Distance Ladder
... C. The galaxies in clusters move faster than expected on the basis of the luminous matter. D. It explains some of the gravitational lensing that is observed at long distances. ...
... C. The galaxies in clusters move faster than expected on the basis of the luminous matter. D. It explains some of the gravitational lensing that is observed at long distances. ...
Galaxies Slide Show and Videos
... Black holes are thought to be at the center of galaxies. These are extremely dense quantities of matter in space. They have such strong gravitational pulls that nothing – not even light – is fast enough to escape. 10 Mind-Bending Facts About Black Holes ...
... Black holes are thought to be at the center of galaxies. These are extremely dense quantities of matter in space. They have such strong gravitational pulls that nothing – not even light – is fast enough to escape. 10 Mind-Bending Facts About Black Holes ...
ppt
... evolution AB on long viscous timescale evolution BC on very short thermal timescale evolution CD on moderate viscous timescale evolution CA on very short thermal timescale Thus get long low states alternating with shorter high states, with rapid upwards and downward transitions between them – dw ...
... evolution AB on long viscous timescale evolution BC on very short thermal timescale evolution CD on moderate viscous timescale evolution CA on very short thermal timescale Thus get long low states alternating with shorter high states, with rapid upwards and downward transitions between them – dw ...
Document
... We used to think massive cluster formation to be a thing of the past (the Globular Clusters). First, we began to see evidence of very massive clusters (proto-globular clusters) forming in other galaxies ...
... We used to think massive cluster formation to be a thing of the past (the Globular Clusters). First, we began to see evidence of very massive clusters (proto-globular clusters) forming in other galaxies ...
Self-similar evolution of wind-blown bubbles with mass
... post-shock temperature of T ≈ 1.4 107 K), and a clump electron number density of ne ≈ 104 , the mean free path for electron energy exchange is λ ≈ 5 1015 cm. This is somewhat larger than the width of a clump in a planetary nebula (e.g. Meaburn et al. 1998) but many clumps have long tails along which ...
... post-shock temperature of T ≈ 1.4 107 K), and a clump electron number density of ne ≈ 104 , the mean free path for electron energy exchange is λ ≈ 5 1015 cm. This is somewhat larger than the width of a clump in a planetary nebula (e.g. Meaburn et al. 1998) but many clumps have long tails along which ...
Answer Key 2
... 4. Carbon, nitrogen and oxygen are heavy elements, which accounts for their stable position in the core of the star. True/False lines 12-13 Some of the heavy elements, e.g. carbon, nitrogen and oxygen move into the star’s outer layers. 5. Investigation of the planetary nebulae has been made difficul ...
... 4. Carbon, nitrogen and oxygen are heavy elements, which accounts for their stable position in the core of the star. True/False lines 12-13 Some of the heavy elements, e.g. carbon, nitrogen and oxygen move into the star’s outer layers. 5. Investigation of the planetary nebulae has been made difficul ...
The formation and evolution of galaxies
... • Overcooling leads to the formation of hundreds more small galaxies than are observed. ...
... • Overcooling leads to the formation of hundreds more small galaxies than are observed. ...
the galaxy-halo connection from abundance matching: simplicity
... Klypin et al. in prep. (SD) Gavazzi et al. 2007 (SL) Yang et al. 2009a (CL) Hansen et al. 2009 (CL) ...
... Klypin et al. in prep. (SD) Gavazzi et al. 2007 (SL) Yang et al. 2009a (CL) Hansen et al. 2009 (CL) ...
6 Big Bang Nucleosynthesis - Course Pages of Physics Department
... form a small number of 7 Be and 7 Li. Their abundances remain so small that we can ignore the reactions (e.g., 7 Be + 4 He → 11 C + γ and 7 Li + 4 He → 11 B) which cross the A = 8 bottleneck. Numerical calculations also show that the production of the other stable lithium isotope, 6 Li is several or ...
... form a small number of 7 Be and 7 Li. Their abundances remain so small that we can ignore the reactions (e.g., 7 Be + 4 He → 11 C + γ and 7 Li + 4 He → 11 B) which cross the A = 8 bottleneck. Numerical calculations also show that the production of the other stable lithium isotope, 6 Li is several or ...
MS Word
... 2. Chose six balls of the same composition (and therefore, same density) but different sizes (and therefore, different masses). Record the properties of the balls in table 1. 3. Drop the first ball into the sand. Do no throw the ball or it will destroy your results. Record the HEIGHT ABOVE THE SAND ...
... 2. Chose six balls of the same composition (and therefore, same density) but different sizes (and therefore, different masses). Record the properties of the balls in table 1. 3. Drop the first ball into the sand. Do no throw the ball or it will destroy your results. Record the HEIGHT ABOVE THE SAND ...
Confronting Dark Matter Powered Stars with Recent Results from
... in comparison to a normal Pop III star. Dark Stars are predicted to be cooler, larger, more massive and potentially longer lived, due to their additional energy source. Using the PHOENIX atmospheric code, stellar spectra of very massive DS are calculated to search for spectral signatures of such obj ...
... in comparison to a normal Pop III star. Dark Stars are predicted to be cooler, larger, more massive and potentially longer lived, due to their additional energy source. Using the PHOENIX atmospheric code, stellar spectra of very massive DS are calculated to search for spectral signatures of such obj ...
Theoretical and observational framework Spectroscopic approach
... Fabbian, Recio-Blanco et al. 2003, in preparation • Radiative levitation of metals and helium depletion is detected for HB stars hotter than ~11 000 K in NGC 1904 for the first time. Fe, Ti, Cr and other metal species are enhanced to supersolar values. He abundance below the solar value. • Slightly ...
... Fabbian, Recio-Blanco et al. 2003, in preparation • Radiative levitation of metals and helium depletion is detected for HB stars hotter than ~11 000 K in NGC 1904 for the first time. Fe, Ti, Cr and other metal species are enhanced to supersolar values. He abundance below the solar value. • Slightly ...
stars
... Black holes are thought to be at the center of galaxies. These are extremely dense quantities of matter in space. They have such strong gravitational pulls that nothing – not even light – is fast enough to escape. 10 Mind-Bending Facts About Black Holes ...
... Black holes are thought to be at the center of galaxies. These are extremely dense quantities of matter in space. They have such strong gravitational pulls that nothing – not even light – is fast enough to escape. 10 Mind-Bending Facts About Black Holes ...
Bonjour Eduardo,
... perhaps up to 90% of the break-up velocity. Because of its delta Scuti pulsations, it is an interesting star to try to model as has already been attempted by Suárez et al. 2005. 3. Other stars of interest are some of Corot´s primary targets as shown in this table. With Corot´s expected accuracy, and ...
... perhaps up to 90% of the break-up velocity. Because of its delta Scuti pulsations, it is an interesting star to try to model as has already been attempted by Suárez et al. 2005. 3. Other stars of interest are some of Corot´s primary targets as shown in this table. With Corot´s expected accuracy, and ...
Mode Identification
... ▸ The stellar flux is determined by the metallicity, the effective temperature, the mass and the radius, or equivalently, by the gravity, of the star. ▸ Parameters are often not well known; their errors propagate into the final selection of the best l value. ...
... ▸ The stellar flux is determined by the metallicity, the effective temperature, the mass and the radius, or equivalently, by the gravity, of the star. ▸ Parameters are often not well known; their errors propagate into the final selection of the best l value. ...
Asymptotic Giant Branch stars viewed up-close and far-off
... and 14 N and 13 C to the surface. The change in the surface abundance ratio of 12 C/13 C is from ≈ 90 to ≈ 20 (Charbonnel 1994). The helium core continues to contract. Eventually, helium ignites through the triple-alpha process. Pressure and temperature are independent of each other in the degenerat ...
... and 14 N and 13 C to the surface. The change in the surface abundance ratio of 12 C/13 C is from ≈ 90 to ≈ 20 (Charbonnel 1994). The helium core continues to contract. Eventually, helium ignites through the triple-alpha process. Pressure and temperature are independent of each other in the degenerat ...
Sun, Stars and Planets Part 1: The Sun: its structure and energy
... common feature of BB sources is that they are opaque. At a given T, any body in thermodynamic equilibrium will show a black-body (≈ continuum) spectrum. For a star, the BB spectrum is a good approximation up to a point only – where the stellar atmosphere’s mfp increases, a line spectrum is formed (a ...
... common feature of BB sources is that they are opaque. At a given T, any body in thermodynamic equilibrium will show a black-body (≈ continuum) spectrum. For a star, the BB spectrum is a good approximation up to a point only – where the stellar atmosphere’s mfp increases, a line spectrum is formed (a ...
History of the 2.7 K Temperature Prior to Penzias and Wilson
... By the formula E = σT 4 the effective temperature corresponding to this density is 3º.18 absolute. In a region of space not in the neighbourhood of any star this constitutes the whole field of radiation, and a black body, e. g. a black bulb thermometer, will there take up a temperature of 3º.18 so t ...
... By the formula E = σT 4 the effective temperature corresponding to this density is 3º.18 absolute. In a region of space not in the neighbourhood of any star this constitutes the whole field of radiation, and a black body, e. g. a black bulb thermometer, will there take up a temperature of 3º.18 so t ...
G040141-00 - DCC
... Inertial modes (r-mode) : main restoring force is the Coriolis force (σ~2Ω/3) ...
... Inertial modes (r-mode) : main restoring force is the Coriolis force (σ~2Ω/3) ...
spectral typing of late-type stellar companions to young stars
... of the SRF rather than the true spectra of the primary causes a small error. There are two components of this error. One is that there may be an error in the reported spectral type of the primary; it may be either later or earlier than what we use. On most stars, the difference between various deter ...
... of the SRF rather than the true spectra of the primary causes a small error. There are two components of this error. One is that there may be an error in the reported spectral type of the primary; it may be either later or earlier than what we use. On most stars, the difference between various deter ...
Yellow supergiants as supernova progenitors: an indication of
... In that case, the surface H abundance is strongly depleted, becoming smaller than the He abundance. Measurements of the surface abundances indicating such trends would be a clue to strong mass loss during the RSG phase. As three of the four observed SNe discussed in this paper are of type IIL or IIb ...
... In that case, the surface H abundance is strongly depleted, becoming smaller than the He abundance. Measurements of the surface abundances indicating such trends would be a clue to strong mass loss during the RSG phase. As three of the four observed SNe discussed in this paper are of type IIL or IIb ...
Binding Energy Powerpoint
... High temperature means high kinetic energy of atoms High kinetic energy allows them to get close enough for the nuclear force to take over ...
... High temperature means high kinetic energy of atoms High kinetic energy allows them to get close enough for the nuclear force to take over ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.