Compact objects for everyone: I. White dwarf stars - Rose
... tunnelling. Thermonuclear burning continues until the formation of an iron core. Once iron— the most stable of nuclei—is reached, fusion becomes an endothermic process. However, combustion to iron is only possible for the most massive of stars. When thermonuclear fusion can no longer support the sta ...
... tunnelling. Thermonuclear burning continues until the formation of an iron core. Once iron— the most stable of nuclei—is reached, fusion becomes an endothermic process. However, combustion to iron is only possible for the most massive of stars. When thermonuclear fusion can no longer support the sta ...
Lecture4
... A. Rigel: B8 ( T= 13,400K); Ia (L= 58000 Lsun ), Supergiant (SG) B. Algol: B8 ( T= 13,400K); V (L= 100 Lsun ), Main Sequence (MS) Same color, same T, but different L. How to find the difference? Ans: Width of the spectral lines tells the difference Lines such as H and H , strong for B8 stars, ar ...
... A. Rigel: B8 ( T= 13,400K); Ia (L= 58000 Lsun ), Supergiant (SG) B. Algol: B8 ( T= 13,400K); V (L= 100 Lsun ), Main Sequence (MS) Same color, same T, but different L. How to find the difference? Ans: Width of the spectral lines tells the difference Lines such as H and H , strong for B8 stars, ar ...
radius M
... ("Kapteyn star") et Proxima Centauri (red points), to the NextGen (1997) models with 400 Myr (dashed red line) and 5 Gyr (full black curve). Jupiter’s position is indicated by a black triangle. ...
... ("Kapteyn star") et Proxima Centauri (red points), to the NextGen (1997) models with 400 Myr (dashed red line) and 5 Gyr (full black curve). Jupiter’s position is indicated by a black triangle. ...
Tests and Constraints on Theories of Galaxy Formation and
... The zodiacal component determined by medianed images in the NUDF exceeds the IRTS modeled component by 100 nW m-2 sr-1. Dwek et al. 2006 point out that the IRTS spectrum is better fit by a zodiacal spectrum than a high z Pop.III spectrum. The IRTS NIRBE is most likely due to an under estimate of the ...
... The zodiacal component determined by medianed images in the NUDF exceeds the IRTS modeled component by 100 nW m-2 sr-1. Dwek et al. 2006 point out that the IRTS spectrum is better fit by a zodiacal spectrum than a high z Pop.III spectrum. The IRTS NIRBE is most likely due to an under estimate of the ...
Stellar models and stellar stability
... where B ∝ L/M = constant and C is an integration constant, determined by the boundary conditions. For the Kramers opacity, which is a reasonable approximation for stellar envelopes of moderate temperatures, we find T 8.5 = B (P2 + C). The different solutions are characterized by√the value of C, and ...
... where B ∝ L/M = constant and C is an integration constant, determined by the boundary conditions. For the Kramers opacity, which is a reasonable approximation for stellar envelopes of moderate temperatures, we find T 8.5 = B (P2 + C). The different solutions are characterized by√the value of C, and ...
Origin of the Universe
... • Cloud dense and cold so collapses under its own selfgravity (cold gas has less internal pressure to counteract gravity) • Once collapsed, it immediately warms up because of release of gravitational energy during collapse • All mass and energy concentrated at a geometric point ...
... • Cloud dense and cold so collapses under its own selfgravity (cold gas has less internal pressure to counteract gravity) • Once collapsed, it immediately warms up because of release of gravitational energy during collapse • All mass and energy concentrated at a geometric point ...
Document
... Oscillation frequencies can be used to yield information on the structure and dynamics inside the Sun. ...
... Oscillation frequencies can be used to yield information on the structure and dynamics inside the Sun. ...
vuorinen_neutron_stars
... constraints on nuclear matter EoS due to tension with soft pQCD pressure 4. pQCD constraint useful even if no quark matter present in stars ...
... constraints on nuclear matter EoS due to tension with soft pQCD pressure 4. pQCD constraint useful even if no quark matter present in stars ...
A SUMMARY OF SELF
... 2. Experimental cross sections are often available for reactions related to explosive burning. What is the reason for this? 3. The possibilities to study p-, s- and r-process nuclei in the laboratory are very different. For which of the processes are most (least) experimental data available. What do ...
... 2. Experimental cross sections are often available for reactions related to explosive burning. What is the reason for this? 3. The possibilities to study p-, s- and r-process nuclei in the laboratory are very different. For which of the processes are most (least) experimental data available. What do ...
Chapter 10 Late evolution of low- and intermediate
... helium-burning products at the surface, in particular a large production of carbon. In the 3 M⊙ model shown in Fig. 10.4, the surface 12 C abundance increases after every dredge-up episode and thus gradually increases, until it exceeds the 16 O abundance after 1.3 × 106 yr. The star has thus turned ...
... helium-burning products at the surface, in particular a large production of carbon. In the 3 M⊙ model shown in Fig. 10.4, the surface 12 C abundance increases after every dredge-up episode and thus gradually increases, until it exceeds the 16 O abundance after 1.3 × 106 yr. The star has thus turned ...
Lecture 6: The main sequence
... Dynamic equilibrium Stars are stable, because cooling leads to contraction and heating, while overheating leads to cooling and expansion. However, since gas pressure depends on temperature, stars must remain hot, and hence they must radiate. In order to replenish the energy lost to radiation, stars ...
... Dynamic equilibrium Stars are stable, because cooling leads to contraction and heating, while overheating leads to cooling and expansion. However, since gas pressure depends on temperature, stars must remain hot, and hence they must radiate. In order to replenish the energy lost to radiation, stars ...
Chapter 1
... The heat that we feel when when we hold a hand over an electric light bulb or lie on a beach on a hot, sunny day is produced by electromagnetic radiation. In the Sun’s core the temperature is around 15 million K. Atoms cannot exist at the extremely high temperatures in the inner regions of the Sun. ...
... The heat that we feel when when we hold a hand over an electric light bulb or lie on a beach on a hot, sunny day is produced by electromagnetic radiation. In the Sun’s core the temperature is around 15 million K. Atoms cannot exist at the extremely high temperatures in the inner regions of the Sun. ...
Texts - mistergui
... exhausted its supply of hydrogen in its core, and is currently fusing helium into carbon. The Sun will be at this stage too, but not for another 6 billion years! What this means, though, is that the star is already past its red giant stage. As it was running out of hydrogen in its core, it swelled u ...
... exhausted its supply of hydrogen in its core, and is currently fusing helium into carbon. The Sun will be at this stage too, but not for another 6 billion years! What this means, though, is that the star is already past its red giant stage. As it was running out of hydrogen in its core, it swelled u ...
Habitable Zone
... • about 30-40 times less abundant than Sun-like stars. • ~1000 times shorter life ...
... • about 30-40 times less abundant than Sun-like stars. • ~1000 times shorter life ...
DOC
... which the waves propagate. In a star this cavity is the interior of the star itself, or a fraction of it. Hence, through Asteroseismology – i.e. by studying the oscillations of stars - astronomers can probe stellar interiors. Since the interiors of stars are hidden from direct observation, stellar o ...
... which the waves propagate. In a star this cavity is the interior of the star itself, or a fraction of it. Hence, through Asteroseismology – i.e. by studying the oscillations of stars - astronomers can probe stellar interiors. Since the interiors of stars are hidden from direct observation, stellar o ...
The Milky Way II AST 112
... – Matter is altered and returned to the ISM throughout the star’s life and when it dies – This is called the Star-Gas-Star Cycle ...
... – Matter is altered and returned to the ISM throughout the star’s life and when it dies – This is called the Star-Gas-Star Cycle ...
Make Your Own Star Bracelet
... telescopes. We must look for them by their heat, looking at their infrared radiation." "The next two beads tell us of two possible endings for stars." (pick up the metallic bead) "Pick up the metallic bead and thread it onto the cord. When some stars grow old, they blow off their outer layers of gas ...
... telescopes. We must look for them by their heat, looking at their infrared radiation." "The next two beads tell us of two possible endings for stars." (pick up the metallic bead) "Pick up the metallic bead and thread it onto the cord. When some stars grow old, they blow off their outer layers of gas ...
スライド 1 - Astrophyics Lab. in Kagoshima University
... – finding new phenomenon, classification – developing new technique – implication to new possibility ...
... – finding new phenomenon, classification – developing new technique – implication to new possibility ...
Dark Matter Capture in the first stars
... • DM heating disassociates molecular hydrogen, and then ionizes the gas • Our proto star has now become a star. – Initial star is a few solar masses – Accrete more baryons up to the Jeans Mass~1000M ...
... • DM heating disassociates molecular hydrogen, and then ionizes the gas • Our proto star has now become a star. – Initial star is a few solar masses – Accrete more baryons up to the Jeans Mass~1000M ...
Biography and Autobiography
... At my house, I was the oldest of three sisters. Next door to us, there lived another three girls. They were all younger than me, too. Whenever we played together, I was in charge of what we did. I was the director of the play, or the mom in a pretend family. Sometimes I was the doctor who saved thei ...
... At my house, I was the oldest of three sisters. Next door to us, there lived another three girls. They were all younger than me, too. Whenever we played together, I was in charge of what we did. I was the director of the play, or the mom in a pretend family. Sometimes I was the doctor who saved thei ...
More than You Ever Wanted to Know about Autoguiding
... What this means is that if you have 5 pixels of blur due to seeing, and the star moves three pixels during the exposure (or between corrections), the final blur will be the square root of 5^2 +3^2, or 5.83 pixels in length. Perpendicular to the movement the star is 5 pixels in diameter, so the final ...
... What this means is that if you have 5 pixels of blur due to seeing, and the star moves three pixels during the exposure (or between corrections), the final blur will be the square root of 5^2 +3^2, or 5.83 pixels in length. Perpendicular to the movement the star is 5 pixels in diameter, so the final ...
Origin_of_Elements in the stars
... is about one light-year in diameter, and is located some 2,000 light-years from Earth. The colors are approximately true colors, and represent three different chemical elements: helium (blue), oxygen (green), and nitrogen (red). Web Reference http://apod.nasa.gov/apod/ap091115.html ...
... is about one light-year in diameter, and is located some 2,000 light-years from Earth. The colors are approximately true colors, and represent three different chemical elements: helium (blue), oxygen (green), and nitrogen (red). Web Reference http://apod.nasa.gov/apod/ap091115.html ...
Lesson 16.3
... From Earth, the stars in a constellation may look close together. They may look this way because they are in the same direction from Earth. But the stars might actually be very far apart. People in different parts of the world see different constellations. Earth can be divided into two parts along t ...
... From Earth, the stars in a constellation may look close together. They may look this way because they are in the same direction from Earth. But the stars might actually be very far apart. People in different parts of the world see different constellations. Earth can be divided into two parts along t ...
Methods of Determining Relative Age of Young Stellar Objects
... main sequence stars do not show emission lines. For instance, very young stars show an abnormally strong lithium absorption line, whereas main sequence stars do not show lithium. However in this project most of the red end spectra were not obtained since poor weather conditions prevented it. Other l ...
... main sequence stars do not show emission lines. For instance, very young stars show an abnormally strong lithium absorption line, whereas main sequence stars do not show lithium. However in this project most of the red end spectra were not obtained since poor weather conditions prevented it. Other l ...
Abstract
... mass of 109 M (where M is the solar mass) building up a total mass of 1011 M. The overdensity region of this mass-scale decouples from the cosmic expansion at redshift 7.8 (0.65109 yr after the Big-Bang) at a radius of 53.7 kpc (1 kpc=3,260 light yr), where the initial conditions are set up. The ...
... mass of 109 M (where M is the solar mass) building up a total mass of 1011 M. The overdensity region of this mass-scale decouples from the cosmic expansion at redshift 7.8 (0.65109 yr after the Big-Bang) at a radius of 53.7 kpc (1 kpc=3,260 light yr), where the initial conditions are set up. The ...
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.