Astrophysics Flashcards
What is the universe composed of?
A large collection of billions of galaxies
Define a galaxy.
A large collection of billions of stars
What is a solar system?
A collection of planets orbiting a common star
Where is our solar system located?
In the Milky Way galaxy
What is gravitational field strength measured in?
Newtons per kilogram (N/kg)
What is the formula for weight?
weight = mass × gravitational field strength
What does gravitational force enable?
Various bodies to orbit around others
True or False: Moons orbit planets.
True
What shape are the orbits of planets and comets?
Slightly elliptical for planets; highly elliptical for comets
What is the relationship between orbital radius and speed?
The greater the orbital radius, the greater the orbital speed
What happens to a comet’s speed as it gets closer to the star?
It has a greater speed nearer to the star
What initiates the formation of a star?
A cloud of dust & gas called a nebula
What happens to particles in a nebula due to gravity?
They experience a weak attraction and begin to clump together
What is a protostar?
The stage after particles in a nebula clump together
What occurs when pressure and temperature in a star are great enough?
Nuclear fusion occurs
What do hydrogen nuclei fuse to form?
Helium nuclei
What is a main sequence star?
A stable star where outward pressure balances with gravitational pressure
What happens when a star uses up its hydrogen?
It collapses under its own gravitational attraction
What does a star with a similar mass to the Sun become after collapsing?
A red giant
What is the final stage of a star after becoming a white dwarf?
It cools into a black dwarf
What is the sequence of stellar evolution for a massive star?
Nebula → Protostar → Main Sequence Star → Red Supergiant → Supernova → Neutron Star or Black Hole
Fill in the blank: A _______ is the stage after a nebula where particles begin to clump together.
Protostar
What happens to a star with a mass larger than the Sun?
It expands and becomes a red super giant before exploding in a supernova.
The remnants can be either a neutron star or a black hole if exceptionally massive.
What classification method is used for stars?
Stars can be classified according to their colour.
The colour is related to the surface temperature of the star.
What is the relationship between a star’s colour and its surface temperature?
Hotter stars are bluer and cooler stars are redder.
Fill in the blank: A star with a mass larger than the Sun becomes a _______ before it explodes.
red super giant
True or False: A black hole is a possible remnant of a supernova if the star was exceptionally massive.
True
