Topic 7: Astronomy Flashcards
What factor determines the type of lifecycle a star undergoes?
The size of the star
What two phases do all stars of the same or greater size than the sun undergo?
Protostar and main sequence phase
What do stars like the sun become at the end of their life-cycle?
A black dwarf
What two things can starts much bigger than the sun become at the end of their lifecycle?
Neutron star and black hole
What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?
Red giant and white dwarf
What two phases do stars of greater size to the sun go through between being a main sequence star and a neutron star/black hole?
Red supergiant and supernova
What is the transition of the star from the nebula stage to the main sequence?
The nebula increases in size until it’s pulled in due to its gravity, causing GPE to turn into KE, the collision between particles cause this KE to turn into thermal energy and 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 in the star release energy, this energy balance out with the gravitational potential energy leaving the star and the star is in equilibrium so will not collapse due to gravity or expand due to radioactive behaviour, it’s stable
What happens when a star transitions to the red giant stage?
Once all of the hydrogen fuel has been used up, the star begins to fuse helium and other larger nuclei and this cause the star to expand and become a red giant
Hohn does a red giant become a white dwarf?
Once all reactions have taken place, the star’s gravity pulls in all of its mass, making a small dense white dwarf and this will cool down to form a black dwarf
Why are telescopes located outside the earths atmosphere?
The earths atmosphere absorbs many EM waves making it difficult to detect certain waves, light pollution can make some images less clear and telescope in scale can operate both night and day
What is the disadvantage of telescopes located outside the atmosphere?
They’re difficult to maintain as they have to be repaired in space
What are the disadvantages of optical telescopes?
They can only be used at night when the sky is clear and they can’t be used when the weather is cloudy
What is the use of radio telescopes?
They are not weather dependent and they are usually large and expensive
What is the steady state theory?
it says that the inverse has always existed but is expanding and creating matter to counteract the loss in density
