ASTRO-114--Lecture 40-
... bigger, so that over the last 4 billion years it has increased its size probably about 20 percent. It’s not a lot, not over that long a period of time, but it has changed. And it will continue to change because its internal composition continues to change. And you can calculate exactly what it will ...
... bigger, so that over the last 4 billion years it has increased its size probably about 20 percent. It’s not a lot, not over that long a period of time, but it has changed. And it will continue to change because its internal composition continues to change. And you can calculate exactly what it will ...
First firm spectral classification of an early-B pre-main
... and they show a red continuum, likely due to hot dust, and an emission-line spectrum that includes Brγ and, often, CO 2.3 μm bandhead emission. The latter emission can be modeled as being produced by a Keplerian rotating disk surrounding the young, potentially massive star (Bik & Thi 2004; Blum et a ...
... and they show a red continuum, likely due to hot dust, and an emission-line spectrum that includes Brγ and, often, CO 2.3 μm bandhead emission. The latter emission can be modeled as being produced by a Keplerian rotating disk surrounding the young, potentially massive star (Bik & Thi 2004; Blum et a ...
How we found about BLACK HOLES
... If a star like our Sun was at the distance of Sirius B, it would shine like a bright star. It would not be as bright as Sirius A, but it would be quite bright just the same. Since Sirius B is even hotter than our Sun, it should shine at that distance even more brightly than the Sun—yet it does not. ...
... If a star like our Sun was at the distance of Sirius B, it would shine like a bright star. It would not be as bright as Sirius A, but it would be quite bright just the same. Since Sirius B is even hotter than our Sun, it should shine at that distance even more brightly than the Sun—yet it does not. ...
Research Papers-Cosmology/Download/5936
... assume that a radius of pulsar is less than 20 km. The matter density of such star is close to matter density of the atomic nucleis . These stars are called by neutron stars. Their a weight is estimated to range from 1,4 to 3 mass of the suns. The scientists have developed a theory of the neutron pu ...
... assume that a radius of pulsar is less than 20 km. The matter density of such star is close to matter density of the atomic nucleis . These stars are called by neutron stars. Their a weight is estimated to range from 1,4 to 3 mass of the suns. The scientists have developed a theory of the neutron pu ...
Chapter 30: Stars
... However, astronomers can use special filters to observe the chromosphere when the Sun is not eclipsed. The chromosphere appears red, as shown in Figure 30-1B, because it emits most strongly in a narrow band of red wavelengths. The top layer of the Sun’s atmosphere, called the corona, extends several ...
... However, astronomers can use special filters to observe the chromosphere when the Sun is not eclipsed. The chromosphere appears red, as shown in Figure 30-1B, because it emits most strongly in a narrow band of red wavelengths. The top layer of the Sun’s atmosphere, called the corona, extends several ...
FROM MOLECULAR CLOUDS TO STARS 1 Star formation and the
... mass of the stars in the interstellar medium leaving a relatively small fraction (<10 %) of the initial mass in Black Holes or Neutron Stars. In conclusion: the less massive stars last for a longer time, but at the end of their life most of their masses is lost to the cycle. Increasing their masses, ...
... mass of the stars in the interstellar medium leaving a relatively small fraction (<10 %) of the initial mass in Black Holes or Neutron Stars. In conclusion: the less massive stars last for a longer time, but at the end of their life most of their masses is lost to the cycle. Increasing their masses, ...
Topic 4 - The University of Sheffield
... would have to be single to account for the dark matter. They might be detected because accretion of gas and dust would cause emission lines as the gas atoms collide with each other. (2) Disruption of Binaries - if there are a large number of BHs they would be expected to gravitationally disrupt Wide ...
... would have to be single to account for the dark matter. They might be detected because accretion of gas and dust would cause emission lines as the gas atoms collide with each other. (2) Disruption of Binaries - if there are a large number of BHs they would be expected to gravitationally disrupt Wide ...
Estimating Eccentricity of Planetary and Stellar Cores
... of the angular momentum (torque) between planets/stars and their satellites. The larger the mass ratio of the orbitting partners, the larger the observable temporal changes in their relative orbits should be. The currently adopted theory of torque exchange implies "tidal bulges" induced by orbiting ...
... of the angular momentum (torque) between planets/stars and their satellites. The larger the mass ratio of the orbitting partners, the larger the observable temporal changes in their relative orbits should be. The currently adopted theory of torque exchange implies "tidal bulges" induced by orbiting ...
hot CNO cycle
... Even though the average mass white dwarf is 0.6 – 0.7 solar masses the most often observed novae have masses around 1.14 solar masses. These would be white dwarfs composed of Ne, O, and Mg. It is estimated that ~ 1/3 of novae, by number, occur on NeOMg WDs even though they are quite rare. see also R ...
... Even though the average mass white dwarf is 0.6 – 0.7 solar masses the most often observed novae have masses around 1.14 solar masses. These would be white dwarfs composed of Ne, O, and Mg. It is estimated that ~ 1/3 of novae, by number, occur on NeOMg WDs even though they are quite rare. see also R ...
Exploring Space—The Universe: The Vast
... three types of galaxies? Discuss answers from the video. (The universe contains spiral, elliptical, and irregular galaxies.) What type of galaxy is the Milky Way (A spiral galaxy.) Do they think there are types of galaxies that have not yet been discovered? How are galaxies created? Explain that spi ...
... three types of galaxies? Discuss answers from the video. (The universe contains spiral, elliptical, and irregular galaxies.) What type of galaxy is the Milky Way (A spiral galaxy.) Do they think there are types of galaxies that have not yet been discovered? How are galaxies created? Explain that spi ...
The Sun and Stars
... enough to start nuclear fusion. This is the nuclear reaction in which hydrogen atoms are converted into helium atoms and energy is released. Figure 16.12 shows a portion of the Eagle Nebula, the birthplace of many stars. Main sequence Once nuclear fusion begins, a star is in the main sequence stage ...
... enough to start nuclear fusion. This is the nuclear reaction in which hydrogen atoms are converted into helium atoms and energy is released. Figure 16.12 shows a portion of the Eagle Nebula, the birthplace of many stars. Main sequence Once nuclear fusion begins, a star is in the main sequence stage ...
Betelgeuse
... 4. Its brightness has not gotten any dimmer 5. Scientists do not know what will happen to Betelgeuse in the future ...
... 4. Its brightness has not gotten any dimmer 5. Scientists do not know what will happen to Betelgeuse in the future ...
ACTIVITIES for Grades 3-5 (Continued)
... • The Universe is vast and estimated to be over ten billion years old. The current theory is that the Universe was created from an explosion called the Big Bang. Physical Setting 1.2b • Stars form when gravity causes clouds of molecules to contract until nuclear fusion of light elements into heavier ...
... • The Universe is vast and estimated to be over ten billion years old. The current theory is that the Universe was created from an explosion called the Big Bang. Physical Setting 1.2b • Stars form when gravity causes clouds of molecules to contract until nuclear fusion of light elements into heavier ...
Powerpoint Review
... They postulated that the life cycle of a star is dominated by a single factor ...(long pause).. gravity. Gravity is significant at the birth of a star. Stars are born in giant nebulae when, under the pull of gravity, its gases begin to coalesce in areas here and there. It is the beginning of a proce ...
... They postulated that the life cycle of a star is dominated by a single factor ...(long pause).. gravity. Gravity is significant at the birth of a star. Stars are born in giant nebulae when, under the pull of gravity, its gases begin to coalesce in areas here and there. It is the beginning of a proce ...
MHD_of_Accretion_Disks
... Our Sun is unusual in that it is alone - most stars occur in multiple or binary systems. In a binary system, the higher mass star will evolve faster and will eventually become a compact object - either a white dwarf star, a neutron star, or black hole. When the lower mass star later evolves into an ...
... Our Sun is unusual in that it is alone - most stars occur in multiple or binary systems. In a binary system, the higher mass star will evolve faster and will eventually become a compact object - either a white dwarf star, a neutron star, or black hole. When the lower mass star later evolves into an ...
Round2 - Quizbowl Packet Archive
... 14. A subgroup of this phylum is considered paraphyletic because of its non-parasitic nature; that subgroup is Turbellaria. Another species in this phylum grows large numbers of proglottids, which detach and release eggs. These organisms extract reusable material and send it into other cavities by u ...
... 14. A subgroup of this phylum is considered paraphyletic because of its non-parasitic nature; that subgroup is Turbellaria. Another species in this phylum grows large numbers of proglottids, which detach and release eggs. These organisms extract reusable material and send it into other cavities by u ...
SPECTROSCOPY - AST 114, Astronomy Lab II for Spring 2017!
... Fig. 4: Models of electrons in atoms absorbing and emitting light. In some cases, the energy gained by absorbing a photon or through collision is too high. In these cases the electron can be ejected from the atom completely in a process called ionization. When an atom is fully ionized it has lost al ...
... Fig. 4: Models of electrons in atoms absorbing and emitting light. In some cases, the energy gained by absorbing a photon or through collision is too high. In these cases the electron can be ejected from the atom completely in a process called ionization. When an atom is fully ionized it has lost al ...
Climbing the Distance Ladder
... We don’t directly measure a star’s luminosity. We measure its flux (f): the wattage collected per square meter of our telescope mirror. ...
... We don’t directly measure a star’s luminosity. We measure its flux (f): the wattage collected per square meter of our telescope mirror. ...
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.