Stars (C19) Flashcards
3 stages in star formation
nebula
Protostar
Star
Difference between star and protostar
star there is fusion
Describe energy changes in star formation
GPE –> Kinetic energy
causes heating up
leads to high pressure and fusion
Describe the equilibrium in a main sequence star
outward gas and radiation pressure
Inwards gravitational pressure
Name 8 space objects
Star Planet dwarf planet asteroid comet Solar system Galaxy Universe
To form a red giant what size?
0.5 solar masses to 10 molar masses
To form a super red giant what size?
above 10 solar masses
Describe how a red giant forms
Hydrogen fuel runs low, so radiation pressure falls, causing the sun the have excessive inward pressure
this causes fusion of hydrogen in the outer layers to occur
So the outer layers drift apart and the star swells
Describe the life cycle of a small star
Nebula Protostar Main-sequence star Red giant White dwarf and nebula
Describe the life cycle of a large star
nebula protostar Main-sequence Super red giant Neutron star or black hole
What is the Chandrasekhar limit
core of 1.44 solar masses or more will result in a neutron star/black hole
Conditions for neutron star
core between 1.44 solar masses and 3
Conditions for blackhole
core greater than 3 solar masses
What stops a black hole/neutron star in smaller stars from forming
the electron degeneracy pressure resists the gravitational force
why is there electron degeneracy pressure
Pauli exclusion principle
What is the difference between super red giant and red giant
in super, heavier elements up to iron can be fused
What causes a supernova
super red giant starts to fuse iron, which takes more energy than it releases, causing the rapid collapse of the star and explosion
When are elements heavier than iron fused?
in supernova explosions
Where do electrons want to exist
at the lowest energy state (most negative)
Key thing with energy levels
Only discrete, certain jumps are possible, therefore only certain frequencies are emitted/absorbed
What is an excited electron
an electron that has been moved to a higher energy state
What does 0 represent on the electron level diagrams
a free elctron
why is the energy levels for electrons negative
energy is required to remove the electrons
Things that are excited…
quickly move down to lower energy states
What is spectroscopy
Analysis of light to determine the elements within a substance
What are the 3 types of spectrum
Continuous
emission
absorption
Why does a sun emit an absorption spectra
as the sun is a hot body so emits all wavelengths but the gasses on the surface absorb certain wavelengths
what is an emission spectra
unique set of lines for each element due to the specific photons it gives off
What is a diffraction grating
a device with has many slits designed to diffract light
Why are diffraction gratings used
has it seperates different wavelengths of light so reduces blurriness
What colour diffracts most in a diffraction grating
red
What colour diffracts least in a diffraction grating
violet
Why does different colours of light diffract different amounts
Depends on wavelength
What is a blackbody
an abject which absorbs (and therefore emits) a full spectrum of wavelengths
Why do hotter stars have lower peak wavelengths
Energy is inversely proportional to wavelength and energy is proportional to temp
What is Weins displacement constant
2.9 x 10^-3 Km
what is luminosity
total power radiated by a star
What two laws are needed to calculate the size of stars
Wiens and stefans
What is Stefan’s Law
Luminosity is proportional to the radius squared and the temperature to the power of 4
