lec 1- cosmology 1 Flashcards
what is microevolution?
evolution of a population such as mutations and selections within a species
what is macroevolution?
evolutionary changes of a species or higher group (families, major adaptations)
what is speciation?
the process by which new species are created through evolution
what is all life made of?
carbon matter
what are the bio elements?
CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur)
did carbon come from the big bang?
no
what is the expansion of the big bang?
the cooling and condensing of elementary particles
what elements arose from the expansion of the big bang?
hydrogen and helium (plus rare, lithium, boron, beryllium)
what leads to star formation and galaxies by collisions and gravitational attraction?
turbulence in gas clouds
what is the estimated age of the known universe?
13.8 billion years
when did the milky way Galaxy form?
4.5 billion yrs
where is the sun located in the milky way?
in the outer spiral of the milky way
what are the three different star types?
-supergiants: largest in luminosity, can be higher in temp or lower than our sun
-giants: between sun and supergiants in luminosity, higher temp then our sun
-white dwarfs: low luminosity and very cool
what is the main sequence of stars?
the longest phase of all stars, their length in the main phase depends on their mass
how far is our sun in its main sequence?
about half way through the mains sequence of about 10 billion years
what are star cores?
high temperature atomic fusion reactors
how are helium atoms formed in the universe and what happens to the lost mass?
two hydrogen nuclei fuse to form one helium atom which has a lower mass, causing the lost mass to turn into energy ( heat and radiation)
why are stars stable for long periods of time?
because the expansion of heat generated by core fusion is balanced by the contraction due to gravity
what results in the collapse of a star?
when the expansion of heat is reduced, causing unequal pressures
how is carbon formed in the universe?
from 3 helium atoms fusing (helium has a mass of 4, it fuses with itself to make beryllium with a mass of 8, Be (8) + He (4) = C (12) )
how is oxygen formed in the universe?
with 4 helium atoms
when do carbon and oxygen form during a stars life?
after they become a red hot giant, they fuse 4 helium into carbon-12 (the most abundant isotope)
what elements make up the outer rainbow layer of a nebula?
carbon and oxygen
what are the 5 steps of a stars life?
- clouds of hydrogen and dust condenses
- main-phase star burns hydrogen in its core (current earth sun)
- helium core forms as hydrogen shell expands
- star becomes a red giant consisting of carbon core surrounded by a hydrogen envelope
- star finally collapses forming a white dwarf
why is it said that the core of white dwarf stars are full of diamonds?
because the core is filled with carbon
