Astrophysics Flashcards
(45 cards)
What is the universe
A large collection of billions of galaxies
What is a galaxy
A large collection of billions of stars
What is our solar system
The Milky Way galaxy
Why does gravitational field strength differ on different plants
It depends on the planet’s masses and the distance between them. The greater the masses the greater the gravitational force. The greater the distance the smaller the gravitational force.
What are the 4 impacts of gravitational force in the solar system
-causes moons to orbit planets
-causes planets to orbit the sun
-causes artificial satellites to orbit the earth
-causes comets to orbit the sun
What is the orbit of a comet
Elliptical orbit
What is the gravitational field strength on earth
10 N/kg
What is the gravitational field strength on the moon
1.6 N/Kg
How do you calculate the orbital speed
Orbital speed= 2 x pie x orbital radius/ time period
How can stars be classified
By their colour
How can we use colour to classify stars
-hottest stars are blue(33000+ c)
-next hottest are white
-next hottest are yellow
-next coldest is orange
-coldest are red (3700-2000 c)
What type of star is the sun
As low mass star
What is the Stella evolution of low mass stars
Nebula -> protostar -> main sequence -> red giant stage -> white dwarf -> red dwarf
What happens in a nebula -> protostar
-a nebula is a cloud of dust and gas in the universe. The dust and gas attract together due to gravitational forces
-no fusion occurring- the temperature and pressure is not high enough
-the protostar is formed when there is enough mass
What happens in the main sequence of a low mass star
-the gravitational forces are balances by the radiation pressure so the star is stable
-fusion happens -high enough temperature and pressure
What happens in the red giant stage of a low mass star
-the star produces even more energy, radiation pressure increases and the star swells in size getting much bigger
-the surface turns red as it is cooler, this is because the surface is further away from the core
-fusion occurs with elements heavier than hydrogen
What happens in the white dwarf stage of a low mass star
-the gravitational forces collapse the star and it shrinks in size
-the surface is much closer to the core so it heats up
-no fusion- no energy production
What happens in the red dwarf stage of a low mass star
-without any energy production the star cools down and turns red. It will eventually turn black
-no fusion- no energy production
What is the stellar evolution of high mass stars
Nebula-> protostar-> main sequence-> red super giant-> supernova-> either a neutron star or a black hole
What happens in the main sequence of a high mass star
-these stars tend to be hotter and at a higher pressure so they appear white or blue
-fusion is occurring but they can create much heavier elements
-the more mass the star has the shorter the life time
What happens in the red super giant stage of a high mass star
-they are very hot in the center producing lots of energy so the radiation pressure increases and the star swells in size
-still has fusion but for very elements up to iron
-surface becomes red as it cools down as it is so far away from the core where energy is produced
What happens in the supernova of a high mass star
-a huge explosion radiating energy out into the universe
-it occurs when fusion stops abruptly
-the radiation pressure reduces to 0 and the star collapses
What happens in a neutron star of a high mass star
-made up of neutrons and nothing else
-low mass
-no fusion
What happens in a black hole of a high mass star
-a rip in the universe itself-nothing can escape a black hole
-no fusion
