Stars Flashcards
Define a planet
An object in orbit around a star with a mass large enough for its own gravity to give it a round shape that does not undergoes fusion and that has cleared its orbit of most other objects.
planetary satellite
a body in orbit around a planet
Define a comet
A small irregular body made of dust, ice and rock that orbits a star with a highly eccentric elliptical orbit
Define solar system
A planetary system consisting of one star and at least one planet in orbit around it.
Define galaxy
A collection of stars and interstellar dust and gas bound together by their mutual gravitational attraction
Planets are defined by a series of characteristics. Identify all the statements from below that are used to characterise a planet
A Its mass is large enough for its own gravity to give it a round shape
B It has an oxygen-based atmosphere
C It has at least one moon
D It orbits a star
E It has cleared its orbit of most other objects
F It has no fusion reactions
G It has a highly elliptical orbit
H It has liquid water present on its surface
A planet is a body that orbits around a star and has the following 3 characteristics:
- Its mass is large enough for its own gravity to give it a round shape
- It has cleared its orbit of most other objects
- It has no fusion reactions
The other options are not necessary characteristics of planets
Identify the correct definition of a solar system
A A solar system is the collective name for a star and all the objects that orbit that star, including planets and asteroids only
B A solar system is the collective name for a star and all the objects that orbit that star, including planets, comets, and asteroids
C A solar system is the collective name for at least two stars in orbit around each other, and all the objects that orbit those stars, including planets, comets, and asteroids
D A solar system is the collective name for at least two stars in orbit around each other, and all the objects that orbit those stars, including planets and asteroids only
B. A solar system is the collective name for a star and all the objects that orbit that star, including planets, comets, and asteroids
Identify the correct definition of the universe
A The universe is everything except black holes
B The universe is everything — from matter to energy and all of space-time
C The universe is everything except wormholes and black holes
D The universe is everything outside of our galaxy
B The universe is everything — from matter to energy and all of space-time
Define the astronomical unti au
The mean distance of the Earth to the sun
Define the Big Bang Theory
The theory that the universe originated as a small dense and hot region that expanded and cooled forming the structures in the universe we see today
Chandrasekhar limit definition
The maximum mass that a white dwarf can have whilst remaining stable
Define continuous spectrum and give an example of one
A spectrum that covers a full range of frequencies without any gaps. The electromagnetic spectrum is an example of a continuous spectrum
State the definition of the cosmology principle
A principle stating that the universe is isotropic and homogenous
Define Dark Energy
An energy that is responsible for the acceleration in the expansion of the universe which cannot be explained by any observable energy
Define Doppler Effect
The apparent change in the wavelength of a wave as the source moves relative to an observer. For a source moving away the wavelength increases and vice versa
Define electron degeneracy pressure
The outwards force, resisting the inwards force of gravity, produced asa result of multiple electrons not being able to exist in identical states in an energy level
Define emission line spectrum
A series of bright lines at specific frequencies that have been emitted by the gases present. Elements can only release photons if certain energies abs therefore frequencies
What’s a Hertzsprung-Russell diagram
A visual representation of the lifecycle of a star. Plots luminosity against temperature
Define nebula
Nebula are huge clouds of dust and gas, where stars are born
How are nebula are formed
They are formed over millions of years as dust and gas slowly come together due to gravitational attraction to form vast clouds
How do stars forms in nebula
Some regions in the nebula cloud are denser than others and the cloud collapses around these denser regions
Taking a single dense region in a nebula cloud undergoing gravitational collapse describe what happens in terms of energy when such collapse takes place
Work is done by the inward gravity causing the gravitational potential energy to decrease and the kinetic energy of the gas and dust to increase
When a dense in a region undergoes gravitational collapse what happens to the temperature
The temperature increases as it is proportional to the average kinetic energy of the gas and dust which it has been increasing due to the work done by the gravity
