Talk:Nu Persei

Nu Persei, not an RR Lyrae variable, but then why does SIMBAD (and others) say so?

It seems that Nu Persei is not an RR Lyrae star, as it would be the brightest, and the brightest is, in fact, RR Lyrae, according to aavso.org. And according to Horace Smith, the brightest RR Lyrae star has magnitude 7, and most are fainter than magnitude 9.

However, what confuses me most, is that SIMBAD, which I think is most reliable for these data, presents this star as an RR Lyrae Variable: [1]. This is also consistent with its spectral type, F2II - F8II, as RR Lyrae variables are A-F. I have also found other sources stating it is an RR Lyrae star, for example here, using the identifier HR 1135. In 1957 it was already a suspected variable [2]. What's wrong then?

Nu Persei is not to be confounded with NU Persei (NU being variable designation, not the Greek letter of the Bayer designation) which also exists, but it is an eclipsing binary [3]. The Italian Wikipedia states that SIMBAD is wrong stating Nu Persei is an RR Lyrae variable, saying that "component E, whose magnitude varies between 13.42-14.08 with a period of 0.837 days". Then references to aavso.org, which has the same information, or similar, as the NU Persei SIMBAD entry (which is not even close to Nu Persei, so it can't be a component of the other star), this makes me think the Italian Wikipedia should be corrected. Eynar Oxartum (talk) 15:29, 19 September 2017 (UTC)[reply]

Simbad is wrong. I've notified them and they'll probably correct it sooner or later. I thought I'd also annotated the page, but I don't see it. Most of the information you see, including the headline, is derived automatically from published papers. Can you imagine someone having to type it all in? Sometimes the systems mess up with the character recognition, and you get cross-reference errors like this. Notice that the NSVS number on the nu Per page is wrong, it is actually the NSVS number for NU Per (you can look it up yourself here). That is the primary ID in the paper giving the RR Lyrae details, hence it got attached to nu Per. I don't know if NU Per is an eclipsing variable or an RR Lyr star, they can look very similar until you do a detailed study. Wils et al (2006) was a fairly detailed study and it says RR Lyrae type ab, which has an asymmetrical light curve and wouldn't easily be confused with an Algol variable. Lithopsian (talk) 15:45, 19 September 2017 (UTC)[reply]

Its probably worth mentioning, just for fun, that ν Per is about 100 times too luminous to be an RR Lyr variable. The spectral type is in the ballpark but everything else is way off. The 2010 paper probably just looked it up on Simbad and didn't check any further. I just noticed that VSX says NU Per is a classical Cepheid :) The Italian Wiki-article is just flat wrong, they're just guessing and in fact the citation shows that NU Per is many degrees away. Lithopsian (talk) 15:58, 19 September 2017 (UTC)[reply]

Some more for you. The GCVS lists the two brightest RR Lyrae variables as S Eridani (possibly RRc, although probably actually a δ Scuti variable) and 43 Cygni (possible RRab, although probably actually a γ Doradus variable). Lithopsian (talk) 19:27, 19 September 2017 (UTC)[reply]

Sorry for the late reply. Thanks a lot for such accurate information. Surely you add a great value to the Wikipedia with your experience. I will be more critic when checking information on SIMBAD. I am glad they have already fixed that mistake. Eynar Oxartum (talk) 15:14, 3 October 2017 (UTC)[reply]