Physics stars

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  • Created by: abbin003
  • Created on: 23-12-19 16:08
What are nebulae
Gigantic clouds of dust and gas (mainly hydrogen)
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How are nebulae formed
Tiny gravitational attraction between particles of dust and gas pulls the particles towards each other
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What is a protostar
Not yet a star but a very hot, very dense sphere of dust and gas
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What needs to happen for a protostar to become a star
Nuclear fusion needs to start in its core
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What keeps a star in a stable equilibrium
The force from radiation and gas pressure balances the force from the gravitational attraction
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What is a planet
An object in orbit around a star
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What is a planetary object
A body in orbit around a planet
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What are comets
They are small irregular bodies made up of ice dust and small pieces of rock. They orbit the sun
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What is a galaxy
A collection of stars and interstellar dust and gas
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What is the range of mass in which stars become a red giant
Between 0.5 solar mass and 10 solar mass
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What Is the electron degeneracy pressure
When the core of a star begins to collapse under the force of gravity, the electrons are squeezed together and creates pressure which prevents the core from further gravitational collapse. This pressure is called electron degeneracy principle
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What is the Chandrasekhar limit
The electron degeneracy pressure to prevent gravitational collapse only works if the core has a mass less than 1.44 solar mass
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What are the two things that come from a red giant
A white dwarf and planetary nebula
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What happens to stars with solar mass greater than 10 once they've consumed all their hydrogen in ther core
Initially the core begins to collapse under gravitational forces but the helium nuclei from fusion moves fast enough to overcome electrostatic repulsion. So fusion of helium into heavier nuclei occurs. the star expands and become a red supergiant
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What happens once the star becomes a red super giant
Inside the core temperature and pressure are high enough for fusion to occur till you get an iron core
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What happens after a red super giant
A supernova occurs in which a neutron star occurs if the mass of the core is greater than the Chandrasekhar limit but if the core has a great mass than 3solar mass black hole occurs
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What is luminosity
Total radiant power output.
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Why are energy levels negative what happens when an electron has zero energy and what's the most negative energy level
They are negative as external energy is required to remove an electron form an atom hence why electrons with zero energy are free from the atom, most negative energy level is the ground level
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What is excitation and what happens when de excitation occurs
Excitation is when an electron goes up from a lower energy level to a higher one when de-excitation occurs the opposite happens but as energy is conserved a photon is emitted
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What are the three types of spectra
Emission line spectra,continuous line spectra,absorption line spectra
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What's stefan's law
The total power radiated per unit surface area of a black body is directly proportional to the fourth power of the absolute temperature of the black body
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State the value of one astronomical unit (AU) and what is the astronomical unit
150 million km /1.5 times 10 to the 11 meters. It is the average distance from earth to sun
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What is A light year (symbol is ly)
The distance travelled by light in a vacuum in time of one year and has a value of 9.46 times 10 to the power of 15 meters
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How much is one arcsecond
1/3600 degrees
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What is a parsec (symbol pc)and state its value
The distance of which one AU sub tends an angle of one arcsecond and has a value if 3.1 times 10 to the 16 meters
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State the Doppler equation
Δλ/λ ≈Δf/f ≈v/c
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Hubbles law
The recessional speed v of a galaxy is almost directly proportional to its distance d from the earth
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What is red shift
When a galaxy is moving away from earth (receding). Movetowards red end of the spectrum because wavelength appears stretched
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What is blue shift
Galaxy moving towards the earth. Move towards the blue end of the spectrum, because wavelength appears to be shorter
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What is the cosmological principal
On a large scale the universe is homogeneous (every part is the same as every other part) and isotropic (looks the same in every direction) and the laws of physics are universal (the same everywhere)
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What are the two evidences for the Big Bang theory
Hubbles law and microwave background radiation
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Equation for the age of the universe
t≈1/hubbles constant
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Other cards in this set

Card 2

Front

How are nebulae formed

Back

Tiny gravitational attraction between particles of dust and gas pulls the particles towards each other

Card 3

Front

What is a protostar

Back

Preview of the front of card 3

Card 4

Front

What needs to happen for a protostar to become a star

Back

Preview of the front of card 4

Card 5

Front

What keeps a star in a stable equilibrium

Back

Preview of the front of card 5
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