Life Cycle of Stars Flashcards
the word photosphere means
sphere of light
the word chromosphere means
sphere of color
the corona extends several million kilometers and gradually becomes the
solar wind
what part of the sun’s atmosphere can only be seen during a total solar eclipse?
chromosphere
what elements make up the sun’s interior in what percentages?
hydrogen 73.4%, helium 24%
nuclear fusion takes place in what part of the sun?
core
what is the source of the sun’s energy?
nuclear fusion
where does the energy come from in a nuclear reaction?
difference in mass
who developed the famous equation E=mc^2?
Einstein
nuclear fusion can only happen under what conditions?
high temperature, high pressure
what occurs during this reaction?
2 protons turn into 2 neutrons
the sun has enough hydrogen left to continue fusion for how much longer?
5 billion years
hydrostatic equilibrium, inward 1.)________ force must be balanced by outward pressure from the 2.)______ ________ reaction: this means that the sun is not 3.)________ nor 4.)_________ this time
1.) gravitational
2.) Hydrogen fusion
3.) expanding
4.) contracting
when do sunspots form?
when distorted by magnetic field lines
why do sunspots appear dark?
they are cooler than their surroundings
solar_________ is large sheet of ejected gas
prominence
_______ _______ escapes the sun mostly through coronal holes, which can be seen in X-ray images
solar wind
list and describe the four fundamental forces in nature
- gravity - weak, always attractive, and infinite range
- electromagnetic - strong, either attractive or repulsive, infinite range
- weak nuclear force - responsible for beta decay; short range, weak
- strange nuclear force - keeps nucleus together; short range, strong
chromosphere
the lower layer of the atmosphere, below the photosphere
convection
the transfer of energy by motion of fluid
convection zone
the layer just under the surface where energy is transferred by convection
corona
the outermost layer of the atmosphere that extends several kilometers and becomes the solar wind
luminosity
energy radiated by the sun can be calculated from the fraction of energy that reaches earth
nuclear fusion
the combining of 2 or more small atomic nuclei into a large atomic number
photosphere
“sphere of light” is what we see at the surface of the sun
radiation
the transfer of energy through space by electromagnetic waves
radiation zone
the core of the sun where energy is transferred by radiation
solar wind
escapes the sun mostly through coronal holes, which is seen in X-ray images
when does star formation occur and where?
when dust clouds begin to contract under gravitational force; the core
star formation happens when part of a dust cloud (nebulae) begins to _____ under its own _______ force.
contract, gravitational
it then collapses and the center becomes hotter and hotter until ________ ________ begins in the core.
hydrogen fusion
Interstellar cloud starts to contract, probably triggered by a ______ wave or pressure wave from a nearby star. The protostar has finally become a star
shock
why are some protostars unable to fuse hydrogen?
does not have enough mass to have a high temperature
pleiades is an example of
an open cluster
brown dwarf
planet like object
closed star clusters (globular clusters)
old, large, spherical
hydrostatic equilibrium
inward gravitational force must be balanced by outward pressure from hydrogen fusion reaction, not expanding
open star clusters
young, small, randomly shaped
protostar
not a nebula that glows because the pressure of gravity
main sequence star
when a protostar has enough mass to fuse hydrogen
red giant star
large, glows red, fuses helium and other elements
white dwarf
dying star, gradually cooling off (dimming)
black dwarf
dead star, reaching does not give off light
neutron star
core left after a supernova, made of neutrons
nebula
huge cloud of gas and dust, made of hydrogen
black hole
star that collapses on itself because of gravity, light can’t escape
what important characteristic determines the way a star moves through its life cycle?
mass
what is left after a star fuses hydrogen?
helium
supernova
explosion of a star after it can’t fuse elements in the core
absolute magnitude
true brightness of stars
