AS2020: Astronomía ContemporáneaClase # 13

Cosmología

• Profesor: José Maza Sancho

• 10 Noviembre 2010

Distances of Galaxies

• Radar ranging: Astronomical unit• Stellar parallax• Standard candles:• Main-sequence fitting

Cepheid Variables

• In 1912 Miss Henrietta Leavitt discovered the period-luminosity relation.

Type Ia Supernovae

• MB(max) ~ -19.5 (L ~ 5x109 Lo)

• MB(max) versus rate of decline

Hubble’s Law.

v Ho d

Distance Chain Summary

• Radar ranging• Parallax• Main-sequence fitting• Cepheid variables• Type Ia supernovae• Hubble’s law

How do distance measurements tell us the age of the universe.

• Age 12 ~ 15 billion years• Age (CMB) ~ 13.7 billion years

1

Ho

The Horizon of the Universe

How did galaxies form?

Galactic Collisions

NGC 4038 + 4039