Distances Pulling it Together 1 What are ways

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Distances: Pulling it Together 1. What are ways that we know distance? 2. How

Distances: Pulling it Together 1. What are ways that we know distance? 2. How are the measures related? 3. What is the difference between a direct and an indirect measure? 4. What is a standard candle? What are some examples? 5. For what distance scale does each measurement work best?

Distances Radar measurements are DIRCECT measurement. 2 3 P =a

Distances Radar measurements are DIRCECT measurement. 2 3 P =a

Distances We use parallax to get distances to nearby stars.

Distances We use parallax to get distances to nearby stars.

The Shape of the Universe We need to measure distances! FE = L 4

The Shape of the Universe We need to measure distances! FE = L 4 p d 2

Distances: Standard Candles Objects of known luminosity Main Sequence Stars Cepheid Variables Novae Supernovae

Distances: Standard Candles Objects of known luminosity Main Sequence Stars Cepheid Variables Novae Supernovae Spiral Galaxies

Spectroscopic Parallax Recall Lecture Tutorial p. 45

Spectroscopic Parallax Recall Lecture Tutorial p. 45

Cepheid Variables Cepheids have a luminosity-period relationship

Cepheid Variables Cepheids have a luminosity-period relationship

The Distance Ladder Each ‘rung’ on the ladder depends on the previous rung

The Distance Ladder Each ‘rung’ on the ladder depends on the previous rung

The Distance Ladder If the real speed of light was slightly faster than we

The Distance Ladder If the real speed of light was slightly faster than we think A) our distances derived from Cepheids would be too small. B) our distances derived from Cepheids would be too large. C) only our Earth-Venus distance would be affected. D) No distances would be affected.

How do we measure the distances to galaxies?

How do we measure the distances to galaxies?

Cepheids Because the period of Cepheid variable stars tells us their luminosities, we can

Cepheids Because the period of Cepheid variable stars tells us their luminosities, we can use them as standard candles.

Type I SN The apparent brightness of a white dwarf supernova tells us the

Type I SN The apparent brightness of a white dwarf supernova tells us the distance to its galaxy (up to 10 billion lightyears).

How do we measure the distances to galaxies?

How do we measure the distances to galaxies?

Standard Candle: Cepheid variable stars with longer periods have greater luminosities.

Standard Candle: Cepheid variable stars with longer periods have greater luminosities.

Tully-Fisher Relation Entire galaxies can also be used as standard candles because a galaxy’s

Tully-Fisher Relation Entire galaxies can also be used as standard candles because a galaxy’s luminosity is related to its rotation speed.

Standard Candle: Type I SN Whitedwarf supernovae can also be used as standard candles.

Standard Candle: Type I SN Whitedwarf supernovae can also be used as standard candles.

Redshifted Galaxy Spectral features of virtually all galaxies are redshifted

Redshifted Galaxy Spectral features of virtually all galaxies are redshifted

Galactic Red Shift Everything is moving away!

Galactic Red Shift Everything is moving away!

The Universe is Expanding The space between galaxies must be increasing

The Universe is Expanding The space between galaxies must be increasing

Hubble’s Law Galaxies are moving away from us V = H 0 D Farther

Hubble’s Law Galaxies are moving away from us V = H 0 D Farther = Faster Large distances are quoted in redshift

Q: How could you find the age of the universe from Hubble’s Law? velocity

Q: How could you find the age of the universe from Hubble’s Law? velocity = distance time velocity = Ho D Ho = 1/time

Expanding Universe Are we at the center? Is the answer ever yes?

Expanding Universe Are we at the center? Is the answer ever yes?

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Chapter 22 Pulling It All Together Integrating andChapter 22 Pulling It All Together Integrating and
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