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3.1 Cosmic Distance Ladder. From these methods: Determine distance (see p 615 including Fig 20.16) . From these methods: Determine distance (see p 626 including Fig 20.16) . From these methods: Determine distance (see p 626 including Fig 20.16) .
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From these methods: Determine distance (see p 615 including Fig 20.16)
From these methods: Determine distance (see p 626 including Fig 20.16)
From these methods: Determine distance (see p 626 including Fig 20.16)
Use surface temperature of “main sequence stars” to infer Luminosity. Given luminosity infer distance (see p 626 including Fig 20.16)
Use pulsation period of variable starts (“Cepheids”) to infer luminosity Given luminosity infer distance (see p 626 including Fig 20.16)
Use “Tully-Fisher relation” to infer galaxy luminosity from rotation speed Given luminosity infer distance (see p 626 including Fig 20.16)
Use “Tully-Fisher relation” to infer galaxy luminosity from rotation speed Given luminosity infer distance (see p 626 including Fig 20.16)
Fig 20.15A redshifted galaxy spectrum Redshift: For small z
Putting together info about speed v and distance d reveals remarkably simple behavior: Km/Sec/Megaparsec 1 Megaparsec = 3.3 million lightyears
Special feature of the Hubble law: It looks the same from any position: