Talk:RW Cephei

1,260 R_☉

Could someone tell me where the old 1,260 R_☉ for RW Cephei came from? It has been on the list of largest stars since 2010, until the 1,535 R_☉ came in. Even several websites at the time gave a radius of ~1,500 R_☉. ----Joey P. - THE OFFICIAL 02:47, 10 October 2017 (UTC)

Where does it say 1,260? Lithopsian (talk) 10:41, 10 October 2017 (UTC)

https://en.wikipedia.org/w/index.php?title=List_of_largest_stars&oldid=522492647 ----Joey P. - THE OFFICIAL 02:49, 11 October 2017 (UTC)

Wikipedia is not a source, and there is no citation in that old version of the page. Anybody could have made that up. In this case it was an anonymous editor with exactly one edit to their name. It would be easy to suspect a hoax, but Wikipedia says assume good faith, so lets just say somebody got carried away and added information that wasn't fully verifiable from a reliable source. Lithopsian (talk) 10:41, 11 October 2017 (UTC)

Thank you. --Joey P. - THE OFFICIAL ^{(Visit/Talk/Contribs)} 03:24, 23 October 2017 (UTC)

Throwing a cat amongst the pigeons

The most recent paper mentioning RW Cephei in Simbad is Liu et al. (2017). It contains explicit luminosity and radius values for RW Cep, 207 L_☉ and 45 R_☉. The "new" red-giant-style properties are derived as part of a bulk calculation of evolved star properties, based on a near distance from a 1979 paper. They are more than a little suspect, since there is widespread acceptance that RW Cep is a highly luminous and distant hypergiant. However, it is worth remembering that the luminosity value currently in the starbox is from a 1978 paper and the various radius values are based on Stefan-Boltzmann calculations using effective temperatures from different papers, so about as close to the WP:SYNTHESIS line as can be, maybe over it. Any thoughts on what prominence we should give to this paper, if any? I hate to "ignore the data" but it really is likely to be bogus - for example Gaia DR2 gives a distance about 35 times larger than that paper. Lithopsian (talk) 14:57, 14 November 2018 (UTC)

Any papers with both luminosity and temperature?

I'm wondering if any papers have both luminosity and temperature for RW Cep. Nussun05 (talk) 21:16, 18 December 2020 (UTC)

Of course there is. I gave one in the previous section. Perhaps you meant a paper giving values that you liked? There is Chandler (2016), which takes a blind assumption of the Hipparcos distance, but you probably won't like that much either. McDonald (2012 gives the same numbers and it was probably just copied from there. Stassun (2019), the Tess Input Catalog, gives a radius of 1157.920 R_☉, based on the Gaia DR2 parallax. It doesn't actually show the luminosity it derived, but is is calculated in a standard way using the distance, extinction, and a bolometric luminosity derived from the temperature. It is all probably as reliable as the distance, which is probably more sensible than Hipparcos, but still not very reliable: the excess astrometric noise is high, and the angular diameter of the star is an order of magnitude bigger than the parallax. Gaia EDR3 isn't really any better and gives a very large distance. Gaia DR2 gives a temperature 3,688 K in the main table and a bolometric absolute magnitude of −7.855 in the "Long Period Variable stars" table, but they are both fairly crude estimates and both probably too low due to extinction. Lithopsian (talk) 21:44, 18 December 2020 (UTC)

2022 dimming

The light curve data from AAVSO reveal the star is currently dimming beyond average pulsation, although no scientific papers have made a report yet. Can AAVSO be cited as a reliable source or should we wait until a peer-reviewed article is published? VY Canis Majoris (talk) 06:21, 22 November 2022 (UTC)

It has now been reported to The Astronomer's Telegram so I've added it to the page. VY Canis Majoris (talk) 08:26, 15 December 2022 (UTC)

Berkeley 94 membership

The Gaia data suggests it is a member, but no reliable sources seem to explicitly state if the star is a member or not. VY Canis Majoris (talk) 16:35, 27 January 2023 (UTC)

I think the source I added is as good as it is going to get. It suggests it may be a member, but doesn't 100% claim it, so neither does the article. Lithopsian (talk) 16:42, 27 January 2023 (UTC)

To me, it only mentions RW Cep because it happens to be nearby, and does not give any comments on membership. VY Canis Majoris (talk) 17:11, 27 January 2023 (UTC)