Stars Flashcards
(21 cards)
How is a star formed?
Huge clouds of gas and dust called STELLAR NEBULAE.
The gas it consists is mostly HYDROGEN.
The clouds come together because of GRAVITY.
The hydrogen particles start to spiral inwards in a process known as GRAVITATIONAL COLLAPSE.
The gas cloud spins and the PRESSURE AND TEMPERATURE INCREASES.
Potential energy is converted into kinetic energy and the centre of the cloud HEATS UP.
The superheated gas and dust are pulled together to form a PROTOSTAR.
When the temperature reaches about 15 MILLION degrees C NUCLEAR FUSION starts.
We now call this a MAIN SEQUENCE STAR.
When making the planets, what is the term which describes the dust sticking together because of gravity?
Accretion!
What is spectroscopy?
The use and study of light.
How are all the naturally occurring elements apart from hydrogen formed?
By nuclear fusion in stars.
How long does a star last as a red giant?
About a billion years.
What is the life cycle of a star with similar mass to our sun?
Protostar
Main sequence
Red giant
White dwarf
Black dwarf
What is the life cycle of stars that are much more massive than our sun?
Protostar
Main sequence
Red Supergiant
Supernova
Neutron Star or Black Hole
What was the process of the Big Bang?
Rapid expansion and cooling ~ protons and neutrons formed
Further expansion and cooling ~ protons and neutrons join together to create nuclei
Further expansion and cooling ~ electrons combine with nuclei to form atoms
At what temperature does nuclear fusion begin?
At around 15 million degrees Celsius.
In a star with a mass similar to our sun’s, how long does the red giant phase last?
About a billion years.
When a star much larger than the sun becomes a supernova, what is the scale of the brightness?
The star will shine with the brightness of 10 billion suns for a very short time.
Why is a black hole given that name?
They have such enormous magnetic fields that nothing can escape from them-not even electromagnetic radiation such as light.
When did ‘The Big Bang’ take place?
About 14 billion years ago.
Why is a star stable during the ‘main sequence’ phase?
Because the outward force of thermal expansion is balanced by the inward force of gravity.
In a star of high mass, what is the rate at which HELIUM FUSION occurs like compared to a star of smaller mass?
It occurs much more rapidly.
What does the huge amounts of energy from helium fusion do? What does this turn into?
It pushes the outer layers of the star outwards and it turns into a RED SUPERGIANT.
When the red supergiant starts to collapse, what happens?
The collapse releases gravitational potential energy that heats up and throws off the outer layers of the star in the form of an enormous explosion known as a SUPERNOVA.
How long does a supernova shine for, and how brightly?
For a RELATIVELY SHORT time, (ABOUT A MONTH) the star will shine with the brightness of 10 BILLION suns.
After the supernova stage occurs, what’s left of the star? What is it, what is it like?
The core of the star is all that is left, an unimaginably DENSE object called a NEUTRON STAR.
Give two facts about a neutron star:
-They’re the SMALLEST and DENSEST stars known to exist.
-The have a radius typically of about 10KM.
What happens at the end of the most massive of stars’ lives?
A black hole is created.
