Talk:Cepheid variable
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[edit] 1908 or 1912?
The year of the Period-Luminosity is given as 1908 in the introduction, and appears again as 1912 in Use as a "standard candle". Does anyone have a more reliable source? --Chalom 21:13, 13 July 2006 (UTC)
- I originally made the change from 1912 to 1908 at least in the introduction, but it got reverted back (forward? :-)) to 1912. Anyhow, I have put it back to 1908 in both places and explained (in the article - perhaps unnecessarily at this point) about the 1912 date. I wish to adduce the specific information testifying to the date claims. Quoting from her 1908 article "1777 Variables in the Magellanic Clouds" By Henrietta S. Leavitt, H.A. 60, No. 4, on p.107 she says "It is worthy of notice in Table VI the brighter variables have the longer periods". This is a statement of a period-luminosity relationship. In the 1912 article, "Periods of 25 variable stars in the Small Magellanic Clouds" on pp.1-2 she says "A remarkable relation between the brightness of these variables and the length of their periods will be noticed. In H.A. 60, No. 4, attention was called to the fact that the brighter variables have the longer periods, but at that time it was felt that the number was too small to warrant the drawing of general conclusions. The periods of 8 additional variables which have been determined since that time, however, conform to the same law.... The logarithm of the period increases by about 0.48 for each increase of one magnitude in brightness". BTW, the "8 additional" is on top of 17 from the 1908 article. So she observes and states the relationship in 1908, was unsure about its generality, gathers further results which really gave her no new information, and re-affirms the 1908 observation along with a mathematical expression of the relationship.--Netrapt 05:52, 10 February 2007 (UTC)
