Talk:Yellow hypergiant
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G[edit]
Shouldn't it be spectral type G, since it is a yellow hypergiant.
- I thought so too, but there appear to be a number of scholarly journal articles that use the expression.—RJH (talk) 17:50, 4 October 2009 (UTC)
- YHGs are intrinsically variable too, on timescales of ~decades they change spectral types - e.g. HR8752 or rho Cas looping redwards from F to G/K, or IRC +10 420 heading bluewards from F to A. So they can't really be associated with any particular spectral type. If anything the 'yellow' tag is more a label of their evolutionary state (as hotter post-red supergiant objects) than the actual colour.--Westerlund1 (talk) 18:55, 4 October 2009 (UTC)
- There is a "gap" in the HR diagram known as the yellow void where relatively few stars are found between the red and blue supergiants. Stars found in the gap are generally variable, from Cepheids up to Yellow Hypergiants. There is a fairly clear upper temperature limit to the gap which is about 8,000K for hypergiants. The lower temperature limit is set where stars cease to show variable temperatures, with cooler stars being red supergiants (occasionally red hypergiants). The upper limit is approximately spectral class A2, hardly yellow but the upper temperature limit of the yellow hypergiants. The term white hypergiant has been used occasionally, but doesn't seem to identify a particularly coherent set of stars, just some hotter yellow hypergiants that have not been seen to vary much in temperature, or possibly cool blue hypergiants or LBVs, again with no major variations having been observed. The lower temperature limit of around 4,000K is approximately K5. Yellow hypergiants have been observed at somewhat hotter and cooler temperatures, and it is to be expected from their extremely fast evolution that sooner or later one will be observed passing completely out of the yellow gap to become a red or blue hypergiant. Lithopsian (talk) 20:25, 26 October 2012 (UTC)
Usefullness?[edit]
Does this article really have anything to say that isn't said equally well elsewhere already? Perhaps it should be saying something useful but isn't? Lithopsian (talk) 20:16, 26 October 2012 (UTC)