The Expanding Universe 2

Question 1

what did 20th century astronomers take photos of enabling them to measure the Doppler shift and thus the radial velocity?

Answer 1

photographed the spectra of galaxies

Question 2

who obtained the first measurement of Andromeda galaxy?

Answer 2

vesto slipher

-1912

Question 3

what does it mean when galaxies are redshifted?

Answer 3

they are moving away from us

Question 4

what did Hubble use in order to determine distances to these galaxies?

Answer 4

he used cepheid variable stars

Question 5

Hubble found that the further away a galaxy was, the larger its _____ _____?

Answer 5

recessional velocity

Question 6

what is the most fundamental method for distance?

Answer 6

stellar parallax

Question 7

by measuring the brightness of an object, we can derive what?

Answer 7

distance

Question 8

brightness formula

Answer 8

luminosity/4 x pi x d^2

-d is distance to the standard candle

Question 9

what are three types of standard candles?

Answer 9

• main sequence stars
• cepheid variable stars
• type Ia (white dwarf) supernovae

Question 10

what are cepheid variable stars:

Answer 10

pulsating stars that vary in light output

Question 11

type Ia supernova result from the detonation of what kind of stars?

Answer 11

white dwarf stars when their mass is over 1.4 solar masses

Question 12

what is the name for what type-1nsupernova can be categorized under? (SC)

Answer 12

standard candles

Question 13

are type Ia supernova luminous?

Answer 13

yes, very!

Question 14

what does type Ia supernova’s high luminosity allow us to do?

Answer 14

they can be seen to distances of billions of parsecs

Question 15

what is Hubble’s law (plus formula)

Answer 15

relation b/w distance and velocity

v = H x d

Question 16

what is the Hubble Law telling us about the Universe?

Answer 16

that it is expanding

Question 17

what is a Big Bang Universe?

Answer 17

universe in the past when separation of galaxies was very small…beginning of the universe

Question 18

what causes the redshifting of galaxies?

Answer 18

the expansion of space

-NOT doppler shift

Question 19

what is the cosmological redshift?

Answer 19

when the wavelength of light is stretched as the Universe expands
-motion due to expansion of universe

Question 20

what is the name for the shift of spectral lines to longer wavelengths in a specific galaxy?

Answer 20

galaxy’s redshift

Question 21

redshift formula

Answer 21

obs wvlngth - emitted wvlngth/emitted wvlngth

Question 22

doppler shift

Answer 22

motions of galaxies thru space

Question 23

what causes cosmological redshift?

Answer 23

expansion of the universe b/w time the light was emitted and the time the light was received by us

Question 24

when we measure the cosmological redshift, we still often express it as a _____ velocity?

Answer 24

recessional

Question 25

what is a useful way to measure a large-scale structure?

Answer 25

redshift surveys