Cosmology Flashcards
Star
Giant balls of hot gas that are mostly hydrogen and helium. Not static
and change over time
Star Clusters
Groups of stars held together by the mutual gravitational attraction of each star
Galaxy
A huge star cluster, along with interstellar gas, dust and dark matter
What two measurements used to measure distance
Light years and parsecs
Two ways to measure brightness
Apparent magnitude and Absolute magnitude(10 parsecs)
What is a spectroscopy for?
Used to determine elements present in stars. Spectrometer used to split light into wavelengths and these of visible light indicate different elements
Nuclear fusion
When two hydrogen isotopes fuse to form a helium atom
How is a star structure determined
By the balance between the inwards force of gravity and the outwards force of radiation. Each star has a different balance point depending on its size
Nebula
A cloud of interstellar dust, hydrogen and plasma. (All stars form from a nebula)
Protostar
A collapsing cloud of gas that will eventually become a star
H-R Diagram
Shows the relationship between magnitude and temperature and what group a star is in
Main sequence stars
a group of stars lying on a line running from the top left to bottom right. These of which undergo fusion of hydrogen into helium in their core and these stars are relatively stable
Medium mass stars
These include red giants, planetary nebulas, white dwarf and black dwarfs.
High mass stars
These include Supernovas, neutron stars, nebulas and black holes
Red giant
Astar produced when the core of a sun-sized star runs out of hydrogen
Planetary nebula
A cloud of gas produced when a red giant runs out of fuel
White dwarf
Hot, dense star that is the remains of a red giant. Left over centre of an older star
Black dwarf
Cold, dark remains of a white dwarf in theory
Supernova
A giant explosion that occurs when a star many times larger than the sun runs out of nuclear fuel
Neutron star
Remnant of a supernova, consisting entirely of neutrons
Nebula
A cloud of interstellar dust, hydrogen and plasma
Black hole
A collapsed star so massive that not even light can escape from its gravitational field
Supergiant
Are heavier stars that have greater gravity which compresses the core and makes nuclear fusion occur more rapidly, making them hotter, brighter and have a shorter light cycle
Galaxy formation
Galaxies are formed out of immense clouds of gas and dust that collapse under their gravitational pull. Many small lumps of matter clumped together to form a galaxy
What are the two theories of the universe
The steady-state model and the Big Bang theory
The steady state model
This model states the universe is infinite and has always existed in the same form and the universe doesn’t evolve or change over time
The Big Bang theory
This model states that the universe expanded from a single point to the infinite space it is today. The entire mass of the universe was compressed into a super hot dense ball and it is still expanding today
What is evidence to support the steady state model
Galaxies are spread relatively evenly across the sky
Evidence to support the big bang theory
The red shift, cosmic background radiation and abundance of elements
The redshift
As stars move away from us, the light waves are lengthened. Objects seem redder than they are
Cosmic microwave background radiation
In 1965 two American astronomers discovered a low frequency background radiation coming equally from all directions in the sky (afterglow)
Abundance of elements
The levels of specific elements predicted in the bang correlate with levels of these elements in the universe
How old is the universe
13.7 billion years old
