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The section on "Eclipsing binaries" uses relative descriptions of time: "In the last decade ... Recently". This isn't a good idea, as it means the article ages badly. It would be much better (and more future-proof) if it gave approximate dates instead. -- Finlay McWalter | Talk 22:40, 15 December 2006 (UTC)
Population I/II Cepheids
I think that the last paragraph is incorrect; however, I am not an expert. My understanding is that:
- The Population II Cepheids, or W Virginis variables, have lower luminosity, than the Population I, or classical, Cepheid variables.
- The distances in the Milky Way had been measured using W Virginis variables (and RR Lyrae variables, also Population II stars).
- The extra-galactic distances had been measured using classical Cepheid variables.
- When W. Baade discovered the star populations, only the extra-galactic distances were affected. The distances in the Milky Way were not affected.
JTMnen 07:57, 28 August 2007 (UTC)
In order to further developing this article, it may be a good idea to include an extensive section on measuring cosmic distances. I think this section should discuss each of the significant methods, along with their respective strengths and weaknesses (in terms of accuracy and range). Here is a candidate list:
- Trigonometric parallax
- Variables: Eclipsing binary, Cepheid variable, RR Lyrae variables, Novae
- Planetary nebula luminosity function
- Globular Clusters (via main sequence curve)
- Tip of the red giant branch
- VLBI: Radio jet proper motion
- VLBI: Maser proper motion
- Sunyaev-Zel'dovich effect
- Surface brightness fluctuation
- Tully-Fisher relation
- D-sigma relation (ellipticals)
- X-ray burster
- Brightest cluster galaxy
- Type Ia supernovae
- Gravitationally lensed quasars
- Gamma ray bursters
- Coalescing massive black holes