stars_2nd_edit
... years for massive stars to billions for smaller stars. Our Sun, which is of average mass, is predicted to live for about 10 billion years. By knowing the distance, mass, magnitude, and chemical composition of a star, we can determine approximately how old it is, when it was born, and when it will di ...
... years for massive stars to billions for smaller stars. Our Sun, which is of average mass, is predicted to live for about 10 billion years. By knowing the distance, mass, magnitude, and chemical composition of a star, we can determine approximately how old it is, when it was born, and when it will di ...
Document
... • High Mass stars often times explode! • This spreads all of the elements Hydrogen through Iron (which makes up our planets and other new stars) and forms all elements after Iron (up to element 92). ...
... • High Mass stars often times explode! • This spreads all of the elements Hydrogen through Iron (which makes up our planets and other new stars) and forms all elements after Iron (up to element 92). ...
Supernovae Gamma-Ray Bursts and and some of their uses
... Core collapse in massive stars In a massive star, core temperature can be high enough that nuclear burning of Si to Fe can occur. Beyond Fe, further fusion is endothermic, and will not occur under equilibrium conditions. As an iron core develops, other reactions still proceed at larger radii: `Onio ...
... Core collapse in massive stars In a massive star, core temperature can be high enough that nuclear burning of Si to Fe can occur. Beyond Fe, further fusion is endothermic, and will not occur under equilibrium conditions. As an iron core develops, other reactions still proceed at larger radii: `Onio ...
Ay123 Fall 2011 STELLAR STRUCTURE AND EVOLUTION Problem Set 1
... a. Find an expression for the central density in terms of R and the mass M of the star. b. Use the equation of hydrostatic equilibrium and zero boundary conditions to find the pressure as a function of radius. Your answer will be in the form p(r) = pc × f (r/R), where f (x) is a function you will de ...
... a. Find an expression for the central density in terms of R and the mass M of the star. b. Use the equation of hydrostatic equilibrium and zero boundary conditions to find the pressure as a function of radius. Your answer will be in the form p(r) = pc × f (r/R), where f (x) is a function you will de ...
Document
... • For stars less than 6Mo these last slides describe the evolution pretty well. There are some differences in the details that depend on the initial main-sequence mass. • For stars that start with 4Mo, it gets hot enough in the cores to (1) avoid the helium flash and (2) to start carbon fusion. • Th ...
... • For stars less than 6Mo these last slides describe the evolution pretty well. There are some differences in the details that depend on the initial main-sequence mass. • For stars that start with 4Mo, it gets hot enough in the cores to (1) avoid the helium flash and (2) to start carbon fusion. • Th ...
Friday, April 26
... Super-Massive Stars end up as Black Holes • If the mass of the star is sufficiently large (M > 25 MSun), even the neutron pressure cannot halt the collapse – in fact, no known force can stop it! • The star collapses to a very small size, with ultrahigh density • Nearby gravity becomes so strong tha ...
... Super-Massive Stars end up as Black Holes • If the mass of the star is sufficiently large (M > 25 MSun), even the neutron pressure cannot halt the collapse – in fact, no known force can stop it! • The star collapses to a very small size, with ultrahigh density • Nearby gravity becomes so strong tha ...
Linking Asteroids and Meteorites through Reflectance Spectroscopy
... • Heats their outer layers that expand • The expanded gas cools and pressure drops • Gravity then recompresses the gas ...
... • Heats their outer layers that expand • The expanded gas cools and pressure drops • Gravity then recompresses the gas ...
solution
... pressure, density and temperature of the central region of a protostar. Once the temperature exceeds a few million K, H begins to fuse into He (via the p-p chain in a Sun-sized protostar, or the CNO cycle in a larger one). The energy released in the thermonuclear fusion reactions causes an outward p ...
... pressure, density and temperature of the central region of a protostar. Once the temperature exceeds a few million K, H begins to fuse into He (via the p-p chain in a Sun-sized protostar, or the CNO cycle in a larger one). The energy released in the thermonuclear fusion reactions causes an outward p ...
Announcements - Lick Observatory
... • For stars less than 6Mo these last slides describe the evolution pretty well. There are some differences in the details that depend on the initial main-sequence mass. • For stars that start with > 4Mo, it gets hot enough in the cores to (1) avoid the helium flash and (2) to start carbon fusion. • ...
... • For stars less than 6Mo these last slides describe the evolution pretty well. There are some differences in the details that depend on the initial main-sequence mass. • For stars that start with > 4Mo, it gets hot enough in the cores to (1) avoid the helium flash and (2) to start carbon fusion. • ...
Time Domain Astrophysics in South Africa 2
... YUV420 codec decompressor are needed to see this picture. ...
... YUV420 codec decompressor are needed to see this picture. ...
Presentation
... • Dense regions in molecular clouds (>one million particles per cm3) • If the cloud is big enough, it will undergo gravitational collapse ...
... • Dense regions in molecular clouds (>one million particles per cm3) • If the cloud is big enough, it will undergo gravitational collapse ...
star model
... perfect gas, contracts and heat up as it radiates energy Stars have a negative “heat capacity” = they heat up when their total energy decreases. ...
... perfect gas, contracts and heat up as it radiates energy Stars have a negative “heat capacity” = they heat up when their total energy decreases. ...
Lecture 16, PPT version
... • Electrons packed together as tightly as quantum mechanics allows; their speeds support the WD against gravitational collapse • WD acts a lot like a metal (same temperature and density throughout) • Maximum WD mass = 1.4 Msun (“Chandrasekhar limit”) • WD with mass = 1 Msun is about the size of the ...
... • Electrons packed together as tightly as quantum mechanics allows; their speeds support the WD against gravitational collapse • WD acts a lot like a metal (same temperature and density throughout) • Maximum WD mass = 1.4 Msun (“Chandrasekhar limit”) • WD with mass = 1 Msun is about the size of the ...
Star in a Box
... We start by drawing the axes: •Luminosity up the vertical axis (measured relative to the Sun) •Temperature along the horizontal axis (measured in Kelvin) The stars Vega and Sirius are brighter than the Sun, and also hotter. Where would you put them? Where would you mark the Sun on the plot? ...
... We start by drawing the axes: •Luminosity up the vertical axis (measured relative to the Sun) •Temperature along the horizontal axis (measured in Kelvin) The stars Vega and Sirius are brighter than the Sun, and also hotter. Where would you put them? Where would you mark the Sun on the plot? ...
Stars…Giants, Supergiants, Dwarfs….
... When the pressure goes up, atoms “feel their neighbors” and have identity crises. The atomic energy levels, instead of being crisp and unique, get “fuzzed out”. “Fuzzed out” is technical terminology for a change in the energy which depends on how close the neighbors are, how many of them there are, ...
... When the pressure goes up, atoms “feel their neighbors” and have identity crises. The atomic energy levels, instead of being crisp and unique, get “fuzzed out”. “Fuzzed out” is technical terminology for a change in the energy which depends on how close the neighbors are, how many of them there are, ...
3-Stars AM Adapted - vhs-ees-am
... A H-R diagram is a graph that shows the relationship between the absolute magnitude and temperature of stars. ...
... A H-R diagram is a graph that shows the relationship between the absolute magnitude and temperature of stars. ...
PPT - El Camino College
... What are the surrounding layers made of? What can happen if they get hot enough? For Sun, this takes hundreds of millions of years. ...
... What are the surrounding layers made of? What can happen if they get hot enough? For Sun, this takes hundreds of millions of years. ...
Stellar Evolution - Hays High Indians
... concentrated in the central regions of the galaxy. The X-ray source could be another example of a veiled black hole associated with a Type 2 Quasar. This discovery adds to a CXO 0312 Fiore P3 (CXOUJ031238.9growing body of evidence that our 765134): A possible Type 2 quasar veiled black hole.(Credit: ...
... concentrated in the central regions of the galaxy. The X-ray source could be another example of a veiled black hole associated with a Type 2 Quasar. This discovery adds to a CXO 0312 Fiore P3 (CXOUJ031238.9growing body of evidence that our 765134): A possible Type 2 quasar veiled black hole.(Credit: ...
Stellar evolution
Stellar evolution is the process by which a star changes during its lifetime. Depending on the mass of the star, this lifetime ranges from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.Nuclear fusion powers a star for most of its life. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing through the subgiant stage until it reaches the red giant phase. Stars with at least half the mass of the Sun can also begin to generate energy through the fusion of helium at their core, whereas more-massive stars can fuse heavier elements along a series of concentric shells. Once a star like the Sun has exhausted its nuclear fuel, its core collapses into a dense white dwarf and the outer layers are expelled as a planetary nebula. Stars with around ten or more times the mass of the Sun can explode in a supernova as their inert iron cores collapse into an extremely dense neutron star or black hole. Although the universe is not old enough for any of the smallest red dwarfs to have reached the end of their lives, stellar models suggest they will slowly become brighter and hotter before running out of hydrogen fuel and becoming low-mass white dwarfs.Stellar evolution is not studied by observing the life of a single star, as most stellar changes occur too slowly to be detected, even over many centuries. Instead, astrophysicists come to understand how stars evolve by observing numerous stars at various points in their lifetime, and by simulating stellar structure using computer models.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.