The Expanding Universe 2 Flashcards
what did 20th century astronomers take photos of enabling them to measure the Doppler shift and thus the radial velocity?
photographed the spectra of galaxies
who obtained the first measurement of Andromeda galaxy?
vesto slipher
-1912
what does it mean when galaxies are redshifted?
they are moving away from us
what did Hubble use in order to determine distances to these galaxies?
he used cepheid variable stars
Hubble found that the further away a galaxy was, the larger its _____ _____?
recessional velocity
what is the most fundamental method for distance?
stellar parallax
by measuring the brightness of an object, we can derive what?
distance
brightness formula
luminosity/4 x pi x d^2
-d is distance to the standard candle
what are three types of standard candles?
- main sequence stars
- cepheid variable stars
- type Ia (white dwarf) supernovae
what are cepheid variable stars:
pulsating stars that vary in light output
type Ia supernova result from the detonation of what kind of stars?
white dwarf stars when their mass is over 1.4 solar masses
what is the name for what type-1nsupernova can be categorized under? (SC)
standard candles
are type Ia supernova luminous?
yes, very!
what does type Ia supernova’s high luminosity allow us to do?
they can be seen to distances of billions of parsecs
what is Hubble’s law (plus formula)
relation b/w distance and velocity
v = H x d
what is the Hubble Law telling us about the Universe?
that it is expanding
what is a Big Bang Universe?
universe in the past when separation of galaxies was very small…beginning of the universe
what causes the redshifting of galaxies?
the expansion of space
-NOT doppler shift
what is the cosmological redshift?
when the wavelength of light is stretched as the Universe expands
-motion due to expansion of universe
what is the name for the shift of spectral lines to longer wavelengths in a specific galaxy?
galaxy’s redshift
redshift formula
obs wvlngth - emitted wvlngth/emitted wvlngth
doppler shift
motions of galaxies thru space
what causes cosmological redshift?
expansion of the universe b/w time the light was emitted and the time the light was received by us
when we measure the cosmological redshift, we still often express it as a _____ velocity?
recessional
what is a useful way to measure a large-scale structure?
redshift surveys
