Astrophysics Flashcards
Why does weight vary across plants?
weight is depended on g - weight = mass * g
What is the orbit of planets?
circular around the sun
What is the orbit of satellites?
circular around planets
What is the orbit of comets?
elliptical around the sun
What force makes astronomical objects follow orbits?
gravitational force
State the equation linking orbital speed, orbital radius and time period
orbital speed = 2 * Pi * radius / time period
What colour are the hottest stars?
Blue
What colour are the coldest stars?
red
What is a nebula?
a cloud of gas and dust
Describe the transition of a star from nebula to main sequence:
Nebula increases in size until it is pulled in due to its gravity - causing GPE to turn into KE of molecules
As it gets smaller, particles move faster and collide harder so temperature increases
Eventually the nebula will become dense and hot enough to begin fusion
What occurs in the stage when a star is a main-sequence star?
The fusion releases energy
Main sequence stars turn hydrogen into helium
Thermal energy released causes an outward pressure which balances the inward pressure from gravity
Star is in equillibirum
What happens when a star transitions to the red giant stage?
once all the hydrogen fuel has been used up, the star begins to fuse helium and other larger nuclei
This causes the star to expand and become a red giant
How does a star become a white dwarf from a red giant?
Once all reactions have taken place, the star’s gravity pulls in all of its mass making a small, dense white dwarf
This will cool to form a black dwarf
What stages occour for the evolution of stars that have a mass larger than the sun>
Nebula Main sequence Red supergiant Supernova Black hole / neutron star
What is a supernova?
after the red supergiant, the star will expand and get hotter
Will eventually explode as a supernova - what is left turns into a neutron star or a black hole if large
