3.8 Space Physics Flashcards
How do stars form?
Stars form when enough dust and gas (mainly hydrogen and helium) from space are pulled together by gravitational attraction. Smaller masses may form and be attracted by a larger mass to become planets or even stars.
What happens during the main sequence period of the stars life cycle?
During the ‘main sequence’ period of its life cycle, energy is released by the fusion of hydrogen nuclei to make
hellum nuclei in the core
Why is a star stable?
because the forces within it are balanced.
What happens in the core of the star?
the core (centre of a star) is where the temperature and density are greatest and where most nuclear fusion
Takes place.
The more massive a star, the..
The more massive a star, the hotter its core and the heavier the nuclei it can create by fusion.
What is a stars life cycle determined by?
Stars change over time; they have a life cycle. This life cycle is determined by the mass of the star.
What does a main sequence star use to produce light and heat? And what happens when it runs out of hydrogen?
A main sequence star uses nuclear reactions to produce light and heat. When it runs out of hydrogen, what happens next in its life cycle depends upon its mass
What happens to a larger star, that of greater mass than the sun?
A larger star will swell to become a red supergiant, in which helium nuclei fuse to form carbon, followed by further fusion that produces heavier nuclei such as nitrogen and oxygen. It expands, cools and turns red. The outer layers then blast away as a supernova is formed. The core collapses and depending upon mass, it forms either a neutron star or a black nole.
What happens to a star with similar mass to our sun?
A smaller star, similar to our Sun, follows a different sequence, expanding to become a red giant. It then sheds out layers of gas, exposing the core as a white dwarf and finally cools to become a black dwarf.
Fusion processes in stars?
Fusion processes in stars are the source of energy and produce all of the naturally occurring elements.
What happens when a supernova explodes?
Fusion processes in stars are the source of energy and produce all of the naturally occurring elements. These elements may be distributed throughout the universe by the explosion of a massive star (supernova) at the end of its life.
The solar system? What orbits the sun?
The Earth is one of eight planets orbiting the Sun (a medium sized star), which together with other smaller objects (asteroids, dwarf planets, comets) and moons orbiting several
What is our universe made up of?
Our universe is made up of:
• thousands of millions of galaxies that are each made up of thousands of millions of stars
• our Sun is one of thousands of millions of stars in our galaxy called the Milky Way
What is a moon?
Planets orbit the Sun and a moon is a natural satellite of a planet.
What are artificial satellites?
Artificial satellites orbit the Earth and can be in geostationary or low polar orbits.
