The most important questions to study for the exam
... • Quite low, about 6000 K or less, cool enough that most of the hydrogen atoms are in the ground state, so they cannot absorb light in the Balmer series • Moderate temperature, about 10,000 K, so that most of the hydrogen atoms that are not in the ground state are ionized, leaving few to absorb in t ...
... • Quite low, about 6000 K or less, cool enough that most of the hydrogen atoms are in the ground state, so they cannot absorb light in the Balmer series • Moderate temperature, about 10,000 K, so that most of the hydrogen atoms that are not in the ground state are ionized, leaving few to absorb in t ...
1. Stellar Evolution – Notes Astronomers classify stars according to
... On the H-R diagram, giant and supergiant stars lie above the main sequence, while white dwarfs are below the main sequence. Main-sequence stars are stars like the Sun but with different masses. The mass-luminosity relation expresses a direct correlation between mass and luminosity for main-sequence ...
... On the H-R diagram, giant and supergiant stars lie above the main sequence, while white dwarfs are below the main sequence. Main-sequence stars are stars like the Sun but with different masses. The mass-luminosity relation expresses a direct correlation between mass and luminosity for main-sequence ...
Antares - Emmi
... on Earth. Apollo guardian of the cows pleaded with Hera the queen of the gods to send a scorpion with impenetrable armor to kill Orion which the scorpion succeeded . When the Greeks saw the stars and they way they all connected they saw the scorpion that killed Orion ...
... on Earth. Apollo guardian of the cows pleaded with Hera the queen of the gods to send a scorpion with impenetrable armor to kill Orion which the scorpion succeeded . When the Greeks saw the stars and they way they all connected they saw the scorpion that killed Orion ...
2. Equations of Stellar Structure We already discussed that the
... However, these naive guesses are not very good. The reason is that the “surface” of star is not well defined. A more rigorous treatment must use a more detailed model of the stellar atmosphere. We will discuss a simple stellar atmosphere model in Chapter 4 when we study the energy transport in stars ...
... However, these naive guesses are not very good. The reason is that the “surface” of star is not well defined. A more rigorous treatment must use a more detailed model of the stellar atmosphere. We will discuss a simple stellar atmosphere model in Chapter 4 when we study the energy transport in stars ...
here
... a. They are jumping from a lower to a higher level b. they are jumping from higher to lower c. They are leaving the cloud d. We cannot know how they are moving e. They are jumping from a lower to a higher level and then eventually falling back to the lower level 7. The young, hot star in picture to ...
... a. They are jumping from a lower to a higher level b. they are jumping from higher to lower c. They are leaving the cloud d. We cannot know how they are moving e. They are jumping from a lower to a higher level and then eventually falling back to the lower level 7. The young, hot star in picture to ...
Full 11x8.5" Calendar, High Resolution - Chandra X
... composite image shows this happening in the galaxy known as 4C+29.30 where X-rays from Chandra (blue) have been combined with optical (gold) and radio (pink) data. The X-rays trace the location of superheated gas around the black hole, which is estimated to weigh 100 million times the mass of our Su ...
... composite image shows this happening in the galaxy known as 4C+29.30 where X-rays from Chandra (blue) have been combined with optical (gold) and radio (pink) data. The X-rays trace the location of superheated gas around the black hole, which is estimated to weigh 100 million times the mass of our Su ...
Lecture 8: The Stars - Department of Physics and Astronomy
... Stars spend most of their lives on the main sequence The properties of main sequence stars depend largely on its mass • High mass stars are very luminous, hot and have short lives • Cool stars are faint, cool and have very long lives Hertzsprung Russel (HR) diagram is the key to understand stars ...
... Stars spend most of their lives on the main sequence The properties of main sequence stars depend largely on its mass • High mass stars are very luminous, hot and have short lives • Cool stars are faint, cool and have very long lives Hertzsprung Russel (HR) diagram is the key to understand stars ...
CHAPTER 30: STARS, GALAXIES AND THE UNIVERSE Analyzing
... Supernovas are a thousand times more violent than novas. The explosions of supernovas completely destroy the white dwarf star and may destroy much of the red giant. The Final Stages of Massive Stars Supernovas in Massive Stars Massive stars may produce supernovas as part of their life cycle. After t ...
... Supernovas are a thousand times more violent than novas. The explosions of supernovas completely destroy the white dwarf star and may destroy much of the red giant. The Final Stages of Massive Stars Supernovas in Massive Stars Massive stars may produce supernovas as part of their life cycle. After t ...
May
... NGC4656 is a type SBm barred spiral galaxy in the constellation Canes Venatici (KAY-neez- vë-NAT-ih-si). Popularly known as the Hockey Stick Galaxy, the key features are the angled tilt of the disk and the apparent offset of the core. If observing at low magnification look in the same field of view ...
... NGC4656 is a type SBm barred spiral galaxy in the constellation Canes Venatici (KAY-neez- vë-NAT-ih-si). Popularly known as the Hockey Stick Galaxy, the key features are the angled tilt of the disk and the apparent offset of the core. If observing at low magnification look in the same field of view ...
File
... An electron can ONLY get to next higher level if given the exact amount of required energy. It will then drop back down to its original level, releasing the amount of energy it gained in the form of photons. ...
... An electron can ONLY get to next higher level if given the exact amount of required energy. It will then drop back down to its original level, releasing the amount of energy it gained in the form of photons. ...
Edexcel GCE - physicsinfo.co.uk
... Show that the luminosity of the Sun will increase by a factor of about 3000 due to these changes. ...
... Show that the luminosity of the Sun will increase by a factor of about 3000 due to these changes. ...
E1 Introduction to the universe
... has no source of energy of its own, it contracts and heats up, and its gravity compresses the hydrogen in the layer immediately above it, causing it to fuse faster. This in turn causes the star to become more luminous (from 1,000 – 10,000 times brighter) and expand; the degree of expansion outstrips ...
... has no source of energy of its own, it contracts and heats up, and its gravity compresses the hydrogen in the layer immediately above it, causing it to fuse faster. This in turn causes the star to become more luminous (from 1,000 – 10,000 times brighter) and expand; the degree of expansion outstrips ...
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.