What is the Chandrasekhar Limit?
What does it tell us about the death of massive stars? Answer Star Death – Super Novae Questions ***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question*** Q1. Describe briefly the five observable consequences of a supernova explosion. Answer Q2. Why do massive stars die explosively? What are the five consequences of the explosion? Answer Q3. If a supernova occurred in our part of the galaxy, what would we see in our sky both initially and over the course of a few months? Answer Star Death – Planetary Nebulae Questions ***NOTE: After clicking on the link Answer click the back button on your browser to go back to the question*** Q1. What event occurs just before a star like the sun dies? How will this event ultimately be visible to us? Answer Q2. The death of a low mass star occurs fairly quickly, compared to normal time scales for stellar evolution. Why are we able to easily find such objects in transition? Answer Q3. In what form do
The Chandrasekhar limit is an important value in astrophysics. It is the mass limit at which a nonrotating astral body cannot be supported by the pressure of the electron shells in its atoms anymore, and gravitational collapse occurs. The Chandrasekhar limit is approximately 1.4 solar masses, or 2.85×1030 kg. Use of the Chandrasekhar limit is fundamental in analyzing the evolution and demise of stars. The Chandrasekhar limit comes into play when the nuclear fuel in a star gets used up. Throughout the normal lifetime of the star, the outwards pressure from nuclear reactions counteracts the contracting force of gravity. Eventually, it uses up all its hydrogen fuel and departs from the main sequence. It’s all downhill from there. The star fuses heavier and heavier nuclei until it lacks the temperature and density in its core to fuse anything more, or the core turns to iron, which is the heaviest fusion product that cannot itself be fused to produce more energy. Throughout the turbulent la
As shown in #3 the radius of a white dwarf will decrease as its mass increase. Eventually a limit is reach in that the mass (density) becomes so great that degenerate electron pressure cannot resist the force of gravity and the white dwarf would collapse. This limit, known as the Chandrasekhar limit, is 1.4 solar masses 3. How does the radius of a white dwarf (or neutron star for that matter) vary with mass? In other words does the radius increase of decrease with increasing mass? Also see end of #1 answer on degeneracy. 4. What is needed for a nova to occur? An isolated white dwarf has a boring future: it simply cools off, dimming to invisibility. White dwarfs in binary systems where the companion is still a main sequence or red giant star can have more interesting futures. If the white dwarf is close enough to its red giant or main sequence companion, gas expelled by the star can fall onto the white dwarf. The hydrogen-rich gas from the star’s outer layers builds up on the white dwar
The Chandrasekhar limit is the maximum possible mass for a stable White Dwarf star. The name was given after the Indian-born astrophysicist Subrahmanyan Chandrasekhar, who formulated it in 1930. Using Einstein’s special theory of relativity and the principles of quantum physics, Chandrasekhar showed that it is impossible for a white dwarf star, to be stable if its mass is greater than 1.4 times the mass of the Sun. EXAMPLE: all direct mass determinations of actual white dwarf stars have resulted in masses slightly less than the Chandrasekhar limit. A star that ends its nuclear-burning lifetime with a mass greater than the Chandrasekhar limit must form into either a neutron star or a black hole. What Happens In Time? Pressure from degenerate electrons doesn’t depend on temperature so stars are stable even though no more energy is ever generated within them. Because of electron degeneracy they are unable to contract any further. However, they still have stored energy that will radiate fo
What causes it? What happens if a white dwarf exceeds the Chandrasekhar limit? • Neutron Stars. What is a neutron star? What kind of pressure supports a neutron star? Why are neutrons able to withstand a higher pressure than electrons? • Core Collapse Supernovae. What is a core-collapse supernova? Give an account of the evolution of a massive star just before core collapse. What is the core made of just before core collapse? Why? What has the Chandrasekhar limit got to do with core collapse? How does the core convert into being made of neutrons? • Pulsar. What is a pulsar? The Crab nebula is thought to be the remnant of the Supernova of 1054. How does the Crab nebula support Zwicky’s idea that supernovae result from the collapse of the core of a massive star to a neutron star? • Gamma Ray Bursts. What is a gamma ray burst? There are two kinds of gamma ray burst, short and long (roughly, shorter than 2 seconds, and longer than 2 seconds). What is an afterglow? What evidence suggests tha
