Stellar evolution of a massive star Flashcards
Understand the life cycle of a massive star.
What kind of protostars begin life as blue super giants?
Those with mass more than four times our sun’s mass.
What happens when nuclear fusion begins?
The star enters a stable stage of life in which heat pressure and gravity are in equilibrium.
What’s the difference between fusion on massive stars and that of l-m stars?
It happens at a higher temperature than the temperature at which fusion occurs in a l-m star.
The core of our sun could be 15 million Kelvin, whereas the core of a massive star could be about 40 million Kelvin.
How does the high temperature of massive stars affect its fusion process?
It burns more quickly and the conditions make it possible for further fusion of some of the larger atoms it produces.
What are the larger elements that fusion of helium can produce?
Carbon, Oxygen and Silicon. They have mass numbers that are multiples of the 4 nucleons in Helium.
What happens after the helium fusion?
Stages of Carbon and oxygen burning.
At what point can such a star stop producing energy?
When it has fused to a point where it’s mostly iron.
What happens when the star abruptly stops producing energy?
Its enormous gravitational force that is a consequence of its large mass causes the star to undergo an incredible collapse.
What happens as a result of this collapse?
The sudden decrease in energy produces a sudden burst of energy.
What is this explosion called?
A type 2 Supernova, the most immense burst of energy ever witnessed. About 10 billion times the luminosity of the sun.
What happens after the star has exploded?
The entire star may be completely shattered. But if there remains a central core of stellar material, this will either be a neutron star (core has up to 3 solar masses) or a black hole (core retains >3 solar masses)
How does a star’s life cycle navigate through a H-R diagram?
Protostar, at mid luminosity low temperature. Main sequence, giant, dwarf.
