Talk:RR Lyrae

Light-curve

The diagram needs to be replaced with a better one. The time-scale of the light-curve is too long which obscures the nature of the light variations.--TristramBrelstaff (talk) 07:50, 14 December 2010 (UTC)

Absolute Magnitude

I replaced the obviously incorrect absolute magnitude of 7.29 by the value -0.7 which James Kaler quotes as the mean absolute magnitude for RR Lyrae type stars.--94.30.104.188

I just noticed a value 0.61 by Benedict et al is given in the article text, so I have used this instead.--TristramBrelstaff (talk) 08:17, 14 December 2010 (UTC)

Merge?

It appears that the article RR Lyrae variable should be merged into this article.

Mark75382 (talk) 19:57, 17 March 2012 (UTC)

Although they share a name, they are not about the same topic. Regards, RJH (talk) 23:20, 17 March 2012 (UTC)

month not needed

I do wish people on this project would stop cluttering up the references with surplus information. We do not need to know the month of publication in any regular scientific journal, and still less do we need to know which month a book was published in. By working with a set of semi-collapsed templates one can make the work of adding references easier. Macdonald-ross (talk) 12:41, 25 March 2013 (UTC)

Text reorganization

The text seems to me complete in the amount of information, but not it organization. Some facts are more important than others, and some need to be placed first. I think the use of RR Lyrae variables as standard candles is the most important fact about this star. It is the "type specimen" for its class. That it produced a standard candle should be stated in the first paragraph. Readers should not need to read through paragraphs to get that information. The person who discovered it should be mentioned, but if they were never mentioned the article would still be fine. However, if the article failed to mention that RR Lyrae is the progenitor of a standard candle, then the article would be defective. That is the test of what should go in the first paragraph. So I reorganized the text to place the most important information in the first paragraph. Nick Beeson (talk) 13:44, 3 September 2014 (UTC)

Buggy ly <-> pc conversion?

The text correctly indicates that the distance measured by the HST is about 854 ly, or roughly 262 pc. Indeed, the reference indicates an absolute parallax of 3.82 milliarcseconds (Benedict et al., Section 5.3), which translates to 262 pc, or 3.26*262 ~ 854 ly.

However, the text also indicates that, "combined with measurements from (Hipparcos) and other sources, the result is a distance estimate of 860 ly" which is automatically, and incorrectly, converted to 260 pc (one can immediately see that the conversion is wrong, since 260 < 262 but 860 > 854). Why this exaggerated rounding error happens is puzzling: it is being carried out automatically (i.e. the pc values are not hard-coded, but rather computed from the ly values), so apparently there is a bug in the automatic conversion software.

In reality, the same reference (Benedict et al., Section 5.3) gives the weighted average of all sources as being 3.87 milliarcseconds, which translates to 258 pc, or about 841 ly rather than the spurious 860 figure. Automatic conversion works fairly well in this case, yielding a value of 840 ly from the 258 pc estimate.

Now one might wonder why not follow the original reference, which gives the distance estimate in milliarcseconds and hence in pc, instead of writing down a manually converted ly value? The problem is, if we do this, a similarly bad conversion ensues: the more faithful HST estimate of 262 pc is automatically converted to 850 ly rather than the expected 854 ly.

In summary: the ky <-> pc conversion rounding error is so coarse as to yield blatant errors and prevent actual information from being directly quoted in Wikipedia articles. While this is not fixed, conversions should be checked manually for rounding error acceptability.