Space Flashcards
Black Body Radiators?
Perfect absorbers and emitters of EM waves
Relationship between the peak wavelength and the absolute temperature?
Wien’s Law
λ(max) * T = 2.898x10^-3
The relationship relating the luminosity (power output) to the temperature and surface area?
Stefan-Botzmann Law
L= σAT^4
σ = 5.67x10^-8
What is the luminosity of a star?
The power of its emission or the amount of energy emitted per second
What is an AU?
Astronomical unit
Distance between Earth’s Centre and Sun’s Centre
Measures distances in the solar system
1.5x10^11m
What is a light year?
Distance travelled by light in a year
63000AU
1x10^ 16
What is trigonometric paralax?
Using the distance between the earth and the sun to measure the distance to a nearby star
What is a parsec?
the angle of the parallax is 1/3600
1arcsecond
3.09x10^16m
How can you estimate the luminosity of a star using its intensity and distance?
I = L/4πd^2 and L = 4πr^2σT^4
What is a standard candle?
An object in space with known luminosity
How can you use standard candles to measure distance?
Using the inverse square law I = L/4πd^2
What diagram shows the types of stars?
HR diagram - Luminosity against surface area
The formation of stars?
Dust left from supernovae comes together becoming very hot and dense
Causes a protostar
Protostar heats up until it reaches millions of degrees and the hydrogen nuclei fuse
Nuclear fusion releases energy and creates enough energy to overcome gravitational collapse
What happens to main sequence stars?
Pressure-balanced gravity for the majority of life
Fuses all hydrogen so pressure decreases
Star collapses on itself and the core heats up to fuse helium while the extremities become cooler
This is a red giant
What happens to low-mass stars?
They eventually become white dwarfs
What happens to high-mass stars?
They die more quickly and then supernova leaving a neutron star of black whole
What’s the doppler effect?
The motion of a wave’s source effects the observed frequency
Blueshift?
Object approaches us so observed f is higher
Redshift?
Object is moving away so observed f is lower
What does redshift show?
The universe is expanding at an ever-increasing rate
Relationship between the distance away from us and the velocity of the galaxy?
v = H(0)d
H is Hubble’s constant
They are directly proportional
How was the Hubble constant found?
Using standard candles to find the recessional velocity and ten plotting it against the distance
What is the Hot Big Bang Theory?
The universe started as a very goit and very dense singularity and has been ever-expanding since
What is the controversy with H(0)
No one knows H(0) so you cant calculate the age of the universe
What is the fate of the universe?
Depending on the mass of the universe and therefore it’s density (causing gravity)
The universe will either crunch or expand for ever
What’s an arcminute?
1/60 degrees
What’s an arc second?
The measurement for angles of parallax
1/3600
How would you find the speed of an object using the Doppler effect?
Δ λ / λ = -v / c
Or
Δf / f = v / c
What is dark matter?
Matter that doesn’t interact with EM spectrum
Why don’t we know date of the universe?
H(o) unknown
Dark matter quantity unknown
