Stellar Evolution Before…..During……and After…. The Main
... • The length of time a star spends fusing hydrogen into helium is called its main sequence lifetime ...
... • The length of time a star spends fusing hydrogen into helium is called its main sequence lifetime ...
Day_29
... Helium is then used up in the core. He fusion in an inner shell and H fusion in an outer shell all surrounding a C core. Star gets more luminous and cool, and enters the asymptotic giant branch (AGB). ...
... Helium is then used up in the core. He fusion in an inner shell and H fusion in an outer shell all surrounding a C core. Star gets more luminous and cool, and enters the asymptotic giant branch (AGB). ...
chapter 14 - Astronomy
... 1. The maximum mass that a star can have is about 150 solar masses, because otherwise the internal pressure and huge amounts of energy generated in the core would overwhelm gravity and blow the star apart. 2. The minimum mass that a star can have is about 0.08 solar masses, because otherwise its cor ...
... 1. The maximum mass that a star can have is about 150 solar masses, because otherwise the internal pressure and huge amounts of energy generated in the core would overwhelm gravity and blow the star apart. 2. The minimum mass that a star can have is about 0.08 solar masses, because otherwise its cor ...
Astronomy Assignment #1
... collapsing core is pushed deeper into the star as the core collapses and can now fuse for the first time. Shell Hburning begins. The shell H-burning releases gamma rays that do not have to thermalize out of the core so they hit the envelope with more energy that core gamma rays would and, in effect, ...
... collapsing core is pushed deeper into the star as the core collapses and can now fuse for the first time. Shell Hburning begins. The shell H-burning releases gamma rays that do not have to thermalize out of the core so they hit the envelope with more energy that core gamma rays would and, in effect, ...
The lifes of a star
... Hydrogen and that resulting “ashes” are mainly Helium. The above is just one of a very large number of fusion reactions but it is the most common, and is present in all stars at some stage of their lifes. Other reactions are also important, I will talk about them later. As time goes on the amount of ...
... Hydrogen and that resulting “ashes” are mainly Helium. The above is just one of a very large number of fusion reactions but it is the most common, and is present in all stars at some stage of their lifes. Other reactions are also important, I will talk about them later. As time goes on the amount of ...
Oldest SN
... canonical interstellar medium conditions, expansion rates etc. It should be noted that no data of the apparent brightness of these supernovae at their peak exists. We assume that these are canonical supernovae with an absolute magnitude of -19.6 and then derive their apparent magnitude from their di ...
... canonical interstellar medium conditions, expansion rates etc. It should be noted that no data of the apparent brightness of these supernovae at their peak exists. We assume that these are canonical supernovae with an absolute magnitude of -19.6 and then derive their apparent magnitude from their di ...
4550-15Lecture33
... The energy released in the supernova is astounding. In its first 10 seconds, the 1987A supernova released more energy than the entire visible universe, and 100 times more energy than the Sun will release in its entire 10 billion year lifetime. The supernova begins with the collapse of the stellar co ...
... The energy released in the supernova is astounding. In its first 10 seconds, the 1987A supernova released more energy than the entire visible universe, and 100 times more energy than the Sun will release in its entire 10 billion year lifetime. The supernova begins with the collapse of the stellar co ...
Type Ia supernovae as stellar endpoints and cosmological tools
... uest stars (who could have imagined they were distant stellar explosions?) have been surprising humans for at least 950 years, but probably far longer. They amazed and confounded the likes of Tycho, Kepler and Galileo, to name a few. But it was not until the separation of these events into novae and ...
... uest stars (who could have imagined they were distant stellar explosions?) have been surprising humans for at least 950 years, but probably far longer. They amazed and confounded the likes of Tycho, Kepler and Galileo, to name a few. But it was not until the separation of these events into novae and ...
12-1 MAIN-SEQUENCE STARS
... White dwarfs are the cores of sunlike stars that have collapsed until their gas becomes degenerate. They have no nuclear fuels and slowly cool off; they will eventually become black dwarfs. Because white dwarfs are small, dense, and generate no fusion energy, they are sometimes called compact object ...
... White dwarfs are the cores of sunlike stars that have collapsed until their gas becomes degenerate. They have no nuclear fuels and slowly cool off; they will eventually become black dwarfs. Because white dwarfs are small, dense, and generate no fusion energy, they are sometimes called compact object ...
Chapter 13 The Stellar Graveyard
... and the white dwarf collapses, increasing temperature and density until it reaches carbon fusion temperature. • The carbon inside the white dwarfs are simultaneously ignited. It explodes to form a White dwarf supernova. (Type I). • Nothing is left behind from a white dwarf supernova explosion (In co ...
... and the white dwarf collapses, increasing temperature and density until it reaches carbon fusion temperature. • The carbon inside the white dwarfs are simultaneously ignited. It explodes to form a White dwarf supernova. (Type I). • Nothing is left behind from a white dwarf supernova explosion (In co ...
Birth of Elements
... Where does one begin this story? At the very beginning, when the universe had exploded into being with a bang, with matter and radiation being created, or at a time when stars began to shine? Telling both stories would make this article too long and so I will confine myself to an account of stellar ...
... Where does one begin this story? At the very beginning, when the universe had exploded into being with a bang, with matter and radiation being created, or at a time when stars began to shine? Telling both stories would make this article too long and so I will confine myself to an account of stellar ...
Slide 1
... main sequence. This is the principal feature of the Hertzprung-Russell diagram - a large band of stars forming the diagonal sloping downward from left to right. The evolution of a star is determined predominantly by its mass. Once a star has used up all of its core hydrogen, fusion of the lightest e ...
... main sequence. This is the principal feature of the Hertzprung-Russell diagram - a large band of stars forming the diagonal sloping downward from left to right. The evolution of a star is determined predominantly by its mass. Once a star has used up all of its core hydrogen, fusion of the lightest e ...
Killer Skies
... When modern astronomers turned their telescopes to the location of the guest star, they found a peculiar nebula—now known as the Crab Nebula. The Crab Nebula is called so for its many-legged shape. The ‘legs’ are filaments of gas that are moving away from the site of the explosion at about 1,400 km/ ...
... When modern astronomers turned their telescopes to the location of the guest star, they found a peculiar nebula—now known as the Crab Nebula. The Crab Nebula is called so for its many-legged shape. The ‘legs’ are filaments of gas that are moving away from the site of the explosion at about 1,400 km/ ...
updated
... Eventually those outer layers of the star (what used to be the hydrogen envelope) will disperse into the ISM leaving behind only the hot stellar core. For low mass stars (mass less than about 4 solar masses), the remaining core mass in insufficient to generate a temperature high enough to ignite car ...
... Eventually those outer layers of the star (what used to be the hydrogen envelope) will disperse into the ISM leaving behind only the hot stellar core. For low mass stars (mass less than about 4 solar masses), the remaining core mass in insufficient to generate a temperature high enough to ignite car ...
Introduction to the HR Diagram
... The Hertzsprung-Russell diagram, or H-R diagram, is the periodic table of the stars. It was discovered that when the luminosity (absolute magnitude) of stars is plotted against their temperature (stellar classification) the stars are not randomly distributed on the graph but are mostly restricted to ...
... The Hertzsprung-Russell diagram, or H-R diagram, is the periodic table of the stars. It was discovered that when the luminosity (absolute magnitude) of stars is plotted against their temperature (stellar classification) the stars are not randomly distributed on the graph but are mostly restricted to ...
Variable Stars: Pulsation, Evolution and applications to Cosmology
... Recall equations of stellar structure. Nuclear energy generation rate ε(ρ,T) slowly changes the composition decreasing the amount of Hydrogen and increasing the amount of Helium on a nuclear time scale – the characteristic time for stellar properties to change as a result of nuclear burning: tnuc ~ ...
... Recall equations of stellar structure. Nuclear energy generation rate ε(ρ,T) slowly changes the composition decreasing the amount of Hydrogen and increasing the amount of Helium on a nuclear time scale – the characteristic time for stellar properties to change as a result of nuclear burning: tnuc ~ ...
Document
... The electrons in their core do not become degenerate until the final burning stages. The core at that point consists of iron. Other elements – hydrogen, helium, carbon, oxygen, and silicon, burn in successive layers (moving inward). The luminosity is almost constant, at all stages of the evolution. ...
... The electrons in their core do not become degenerate until the final burning stages. The core at that point consists of iron. Other elements – hydrogen, helium, carbon, oxygen, and silicon, burn in successive layers (moving inward). The luminosity is almost constant, at all stages of the evolution. ...
powerpoint
... from main sequence to white dwarf (which for our sun would be 1 billion years after it leaves the main sequence). • White dwarfs are small and very hot. • With time they cool down. • There is no fusion, so they slowly loose energy and get cooler. ...
... from main sequence to white dwarf (which for our sun would be 1 billion years after it leaves the main sequence). • White dwarfs are small and very hot. • With time they cool down. • There is no fusion, so they slowly loose energy and get cooler. ...
Lecture 39
... S-process path is zig-zag: there is a zag every time there is a non-stable isotope of an element: in that case, the path zags to the next higher atomic number element. The least abundant are those created by only one, particularly by only the p-process. These tend to be both r-process shielded and o ...
... S-process path is zig-zag: there is a zag every time there is a non-stable isotope of an element: in that case, the path zags to the next higher atomic number element. The least abundant are those created by only one, particularly by only the p-process. These tend to be both r-process shielded and o ...
Slide 1
... “The elements have their ultimate origins in cosmic events. Further, different elements come from a variety of different events. So the elements that make up life itself reflect a variety of events that take place in the Universe. The hydrogen found in water and hydrocarbons was formed in the momen ...
... “The elements have their ultimate origins in cosmic events. Further, different elements come from a variety of different events. So the elements that make up life itself reflect a variety of events that take place in the Universe. The hydrogen found in water and hydrocarbons was formed in the momen ...
Astronomy Assignment #1
... 3. How can you detect protostars if the surrounding gas and dust blocks visible light? Protostars emit the maximum of their radiation at infrared wavelengths due to the heat they generate from converting gravitational energy while they collapse into thermal energy. IR radiation has the characteristi ...
... 3. How can you detect protostars if the surrounding gas and dust blocks visible light? Protostars emit the maximum of their radiation at infrared wavelengths due to the heat they generate from converting gravitational energy while they collapse into thermal energy. IR radiation has the characteristi ...
11 Stellar Remnants - Journigan-wiki
... layer of hydrogen and helium. There is far too little gas to ever combust, however. White dwarfs simply continue to cool and reach a core temperature of around 20,000 K. ...
... layer of hydrogen and helium. There is far too little gas to ever combust, however. White dwarfs simply continue to cool and reach a core temperature of around 20,000 K. ...
Supernova
A supernova is a stellar explosion that briefly outshines an entire galaxy, radiating as much energy as the Sun or any ordinary star is expected to emit over its entire life span, before fading from view over several weeks or months. The extremely luminous burst of radiation expels much or all of a star's material at a velocity of up to 7007300000000000000♠30,000 km/s (10% of the speed of light), driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant. Supernovae are potentially strong galactic sources of gravitational waves. A great proportion of primary cosmic rays comes from supernovae.Supernovae are more energetic than novae. Nova means ""new"" in Latin, referring to what appears to be a very bright new star shining in the celestial sphere; the prefix ""super-"" distinguishes supernovae from ordinary novae, which are far less luminous. The word supernova was coined by Walter Baade and Fritz Zwicky in 1931. It is pronounced /ˌsuːpərnoʊvə/ with the plural supernovae /ˌsuːpərnoʊviː/ or supernovas (abbreviated SN, plural SNe after ""supernovae"").Supernovae can be triggered in one of two ways: by the sudden re-ignition of nuclear fusion in a degenerate star; or by the gravitational collapse of the core of a massive star. In the first case, a degenerate white dwarf may accumulate sufficient material from a companion, either through accretion or via a merger, to raise its core temperature, ignite carbon fusion, and trigger runaway nuclear fusion, completely disrupting the star. In the second case, the core of a massive star may undergo sudden gravitational collapse, releasing gravitational potential energy that can create a supernova explosion.The most recent directly observed supernova in the Milky Way was Kepler's Star of 1604 (SN 1604); remnants of two more recent supernovae have been found retrospectively. Observations in other galaxies indicate that supernovae should occur on average about three times every century in the Milky Way, and that any galactic supernova would almost certainly be observable in modern astronomical equipment. Supernovae play a significant role in enriching the interstellar medium with higher mass elements. Furthermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.