sign in sign up
<<
Home , Edwin Hubble, Vesto Slipher

The Resolution: (1889-1953) Measured Distance to Andromeda (M31) • Noticed individual bright in Andromeda

• Calculated the distance using the Period- Relation for Stars The Resolution: Edwin Hubble (1889-1953) Measured Distance to (M31) • Noticed individual bright stars in Andromeda

• Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda

• Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period 2. CALCULATED Luminosity The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda

• Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period 2. CALCULATED Luminosity 3. CALCULATED Distance The Resolution: Edwin Hubble (1889-1953) Measured Distance to Andromeda Galaxy (M31) • Noticed individual bright stars in Andromeda

• Calculated the distance using the Period-Luminosity Relation for Cepheid Variable Stars 1. MEASURED magnitude & Period 2. CALCULATED Luminosity 3. CALCULATED Distance

• Result was MUCH farther than expected... • (2.3 Million Ly - well beyond ) Henrietta Leavitt & Period-Luminosity Relation Cepheid Variables: Bright stars whose Luminosity (energy output) varies every few days Henrietta Leavitt & Period-Luminosity Relation Cepheid Variables: Bright stars whose Luminosity (energy output) varies every few days

Period-Luminosity Relation The Resolution: (1875-1969)

•Obtained ____ Spectra of The Resolution: Vesto Slipher (1875-1969)

•Obtained ____ Spectra of Galaxies

•Found that Galaxy spectra are REDSHIFTED The Resolution: Vesto Slipher (1875-1969)

•Obtained ____ Spectra of Galaxies

•Found that Galaxy spectra are REDSHIFTED

•Used to calculate ______? Redshift: Calculating Velocity

• Relationship between red/blue shift and the velocity:

Δλ v REDSHIFT (Z) = = λ c

• c = speed of light, • λ is the “at rest” wavelength • Δλ is wavelength shift REDSHIFT

Redshift shows up as shifted absorption or emission lines in galaxy spectra REDSHIFT

Redshift shows up as shifted absorption or emission lines in galaxy spectra REDSHIFT

Redshift shows up as shifted absorption or emission lines in galaxy spectra

What part of the EM spectrum would you expect to see high z galaxies? Redshift vs. distance

Blue Yellow Red IR

The most distant galaxies are detected only in the infrared! Expansion of the : Cosmological Redshift

Distant galaxy caused by the “stretching” of light waves as space itself is expanding!

Cosmological Redshift is slightly different from Doppler shift (why?) Hubble’s Law & Hubble Diagram Hubble found that recession velocity of galaxies is proportional to their distance away from us...

(km/s)

v = H0 * d

(Mly) Hubble’s Law & Hubble Diagram Hubble found that recession velocity of galaxies is proportional to their distance away from us...

(km/s)

v = H0 * d

(Mly) ...implying that the Universe is expanding!! Hubble’s Law: The

(km/s)

v = H0 * d

(Mly) Hubble’s law also implies that the Universe has a finite age!

Age = 1/H0