Reach for the Stars – Div. B
... associated with the nebulosity, the stars of the cluster having been formed from the nebula's matter. ...
... associated with the nebulosity, the stars of the cluster having been formed from the nebula's matter. ...
Lives of Stars - Amazon Web Services
... think of stars as being like cars. A small car has a small gas tank, but it also has a small engine that burns gas slowly. A large car has a larger gas tank, but it also has alarger engine that burns gas rapidly. So the small car can travel farther on a tank of gas than the larger car. Small-mass st ...
... think of stars as being like cars. A small car has a small gas tank, but it also has a small engine that burns gas slowly. A large car has a larger gas tank, but it also has alarger engine that burns gas rapidly. So the small car can travel farther on a tank of gas than the larger car. Small-mass st ...
Lecture 5: Stars
... For even more complication stars <0.01M are not really stars as they can not burn H. They are ‘brown dwarfs’ and are very cool and have spectral types LTY (although it is arguable if the Y subtype even exists). So you might see a spectral sequence as OBAFGKMLTY. I won’t ever talk about types LTY. ...
... For even more complication stars <0.01M are not really stars as they can not burn H. They are ‘brown dwarfs’ and are very cool and have spectral types LTY (although it is arguable if the Y subtype even exists). So you might see a spectral sequence as OBAFGKMLTY. I won’t ever talk about types LTY. ...
AmiraPoster3
... variation between the centre of light and the centre of mass. • Due to the heating and temperature dependence of spectral lines, the shift in line centre may vary significantly. • In this study we only used the helium lines for cross-correlation, so these effects can be ignored. • To correct for the ...
... variation between the centre of light and the centre of mass. • Due to the heating and temperature dependence of spectral lines, the shift in line centre may vary significantly. • In this study we only used the helium lines for cross-correlation, so these effects can be ignored. • To correct for the ...
Pp 263-266 - Gravity From The Ground Up
... to somewhere between two and possibly three solar masses. Its actual value is not known: uncertainties in nuclear physics prevent reliable calculations. We have learned that neutron stars can only exist in a rather restricted range of masses, between perhaps 0.1 and two solar masses. In fact, their ...
... to somewhere between two and possibly three solar masses. Its actual value is not known: uncertainties in nuclear physics prevent reliable calculations. We have learned that neutron stars can only exist in a rather restricted range of masses, between perhaps 0.1 and two solar masses. In fact, their ...
Chapter 13
... 28. An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected by the ship would be measured by this observer to travel at A) 0.25c B) 0.5c C) c D) 1.5c E) 2.5c 29. As a spaceship's velocity gets closer to the speed of light A) its length will decrease and its clock will ...
... 28. An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected by the ship would be measured by this observer to travel at A) 0.25c B) 0.5c C) c D) 1.5c E) 2.5c 29. As a spaceship's velocity gets closer to the speed of light A) its length will decrease and its clock will ...
Nucleosynthesis and Energy Production in Stars: Bethe`s Crowning
... Arthur Eddington were the first to point out, independently, that the fusion of four atoms of hydrogen into one atom of helium could release enough energy to resolve the problem of energy production in stars. However, a formal theoretical explanation and clearer picture emerged only after the maturi ...
... Arthur Eddington were the first to point out, independently, that the fusion of four atoms of hydrogen into one atom of helium could release enough energy to resolve the problem of energy production in stars. However, a formal theoretical explanation and clearer picture emerged only after the maturi ...
Problem Set No. 5
... converted a lot of the hydrogen in the interior into helium. (b) The element with the highest density is osmium. It has a density of 22.6 gm/cm3 , twice as dense as lead. Yet the H and He inside the sun can be much denser. At what radius is the density of the solar material equal to that of osmium? ...
... converted a lot of the hydrogen in the interior into helium. (b) The element with the highest density is osmium. It has a density of 22.6 gm/cm3 , twice as dense as lead. Yet the H and He inside the sun can be much denser. At what radius is the density of the solar material equal to that of osmium? ...
Luminosity
... higher energy level when a photon is absorbed = absorption • Excited state • The electron jumps to a lower energy when it emits a photon = emission • Ground state ...
... higher energy level when a photon is absorbed = absorption • Excited state • The electron jumps to a lower energy when it emits a photon = emission • Ground state ...
Low mass star formation
... Core mass function is similar to the IMF (confirmed by recent Herschel results), implies constant star formation efficiency, but ...
... Core mass function is similar to the IMF (confirmed by recent Herschel results), implies constant star formation efficiency, but ...
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.