Stars and redshift Flashcards
What are the stages of a small star?
Nebula, protostar, main sequence star, red giant, white dwarf, lac dwarf
What are the stages of a large star?
Nebula, protostar, main sequence star, red supergiant, supernova, neutron star OR black hole
How does a star initially form?
Stars initially form from a could have dust and gas called a nebula. The force of gravity pulls the dust and gas together to form a protostar.
How does a protostar become a main sequence star?
As the star gets denser, the temperature rises and more particles collide with each other. When the temperature gets high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei. This gives out huge amounts of energy, which keeps the core of the star hot, making it a main sequence star.
How does a main sequence star work?
It enters a long stable period where the outward pressure caused by the nuclear fusion balances with the force of gravity pulling everything inward. It lasts several billion years typically.
How does a main sequence star become a red giant or supergiant?
When the hydrogen runs out, the star swells. It becomes red because the surface cools. Fusion of helium and other elements occur – heavier elements are created in the core of the star.
How does a red giant become a white dwarf?
It becomes unstable and ejects its outer layers of dust and gas. This leaves behind a hot, dense, solid core – a white dwarf.
How does a white dwarf become a black dwarf?
As a white dwarf cools down, it emits less and less energy. When it no longer emits a significant amount, it is called a black dwarf.
How does a red supergiant become a supernova?
Big stars start to expand and contract several times, forming elements as heavy as iron is various nuclear reactions. Eventually they’ll explode in a supernova, forming elements heavier than iron and ejecting them into the universe to form new planets and stars.
How does a supernova become a neutron star?
The exploding supernova throws the outer layers of dust and gas into space, leaving a very dense core called a neutron star.
How does a supernova become a black hole?
If the star is massive enough, it will become a black hole – a super dense point in space that not even light can escape from.
What is the Big Bang Theory?
The Big Bang Theory says the universe started from a tiny, very hot, and dense point called a singularity about 13.8 billion years ago and has been expanding ever since.
What evidence supports the Big Bang Theory?
Evidence includes the cosmic microwave background radiation (leftover from the Big Bang), and the fact that the universe is still expanding.
What is cosmic microwave background (CMB)?
The CMB is faint radiation that fills the universe, leftover from the Big Bang. It shows that the universe was once very hot and compact.
What is red shift?
Red shift happens when light from an object, like a galaxy, is stretched to longer wavelengths, moving toward the red end of the light spectrum. This happens when the object is moving away from us.
How does red shift support the Big Bang Theory?
Red shift shows that galaxies are moving away from us, meaning the universe is expanding, which matches the Big Bang Theory.
What is the Doppler effect in relation to red shift?
The Doppler effect is the change in light or sound as an object moves. If a galaxy is moving away from us, its light shifts toward the red (longer wavelengths), which is called red shift.
What is Hubble’s Law?
Hubble’s Law says that galaxies farther away from us are moving away faster. This shows the universe is expanding, just like the Big Bang Theory predicts.
What is the relationship between red shift and the universe’s age?
The more red shift a galaxy has, the farther away and older it is. This helps scientists estimate the age of the universe.
What is dark energy?
A hypothesised form of energy, believed to be responsible for the universes constant expansion
What is dark mass?
A hypothesised type of mass that cannot be observed by current methods. It is used to explain why some galaxies rotate faster than they should for their observed mass.
What does heliocentric mean?
Heliocentric means that the Sun is at the center of the solar system, with planets orbiting around it.
