stars-- properties and life cycles Flashcards
luminosity measures the total amount of ____ it radiates per _____
energy / second
what does luminosity refer to?
the brightness of stars
our sun is assigned a luminosity of __
1
what colours can stars be?
blue / red / yellow
why is colour used?
to determine the star’s surface temperature
a blue star is _____
hotter
a red star is _____
cooler
a red star is about ____ degrees Celsius
3000
a blue star is about _____ degrees Celsius
18000
what are the 3 levels of mass?
low, intermediate (medium), high
assuming the sun has 1 solar mass, other stars range from ____ solar masses to over ____ solar masses
0.08 / 100
what does the evolution of a star depend on?
the mass it had when it originally formed
what is a red dwarf?
low mass star
what is a red giant?
a dying star that has become large in diameter and cool on the surface
what is a white dwarf?
a small, dim and hot star
what is a black dwarf?
a white dwarf that runs out of heat and energy
what is a neutron star?
a dense star that has only neutrons in its core
what is a black hole?
a region where gravitational force is so strong that nothing can escape it
what is the life cycle for a low mass star?
around 100 billion years => white dwarf => black dwarf
what is the life cycle for an intermediate mass star?
around 10 billion years => red giant => white dwarf => black dwarf
what is the life cycle for a high mass star?
around 100 million years => red supergiant => supernova
=> >40 solar mass => black hole
=> < 40 solar masses => neutron star
on the H-R diagram, where is luminosity?
the y-axis (vertical)
on the H-R diagram, where is temperature and colour?
the x-axis (horizontal)
what does the H-R diagram show?
trends in the evolution of stars
what is a main sequence star?
the central band of stars stretching from the upper left to the lower right (diagonally)
main sequence stars are thought to be what?
at the stable main part of their life cycle
the colour of the star relates to the surface temperature because ___?
blue (left) = hotter (left)
red (right) = cooler (right)
the cool, bright stars in the H-R diagram are ___ _____ the main sequence
far above
