This value of 755 Solar radii is actually from Messineo and Brown et. al. (2019) from Stefan-Boltzmann law. I hand calculated the angular diameter estimate and if you actually went into and read the spreadsheet you'd notice that UY Sct is not anywhere near the top of the list (916 +- 201 Rsol). Current largest is HR 5171 A. But anyway this is the Celestia Origin thread - let Art Blos go back to work.Joey P. wrote:I made a video explanation here on why I don't believe UY Scuti isn't the largest star: https://www.youtube.com/watch?v=OtEKBwJ0oXM
For your argument for the diameter of VY CMa - yes, VY CMa is one of the largest stars with an accurately defined radius. The 1,420 Rsol estimate comes from an angular diameter estimate, with an error of only 120 Rsol (Which is really good!). But, in the paper you referenced, nowhere does it say that the emission area extends out to 2000 Rsol. And even if it does, this can still only be confirmed in the infrared. You claim that this is in fact the visible emission area, which is a conclusion you cannot derive from this paper based on the fact that the telescope used for these observations, Herschel, is an infrared telescope.
So what is the largest star?
There have been recent estimates for NML Cygni and IRAS 05280-6910 that put them above 1600 Rsol, but I wouldn't trust this (Levesque's SBL estimates are not very accurate IMO). I would consider angular diameter estimates to be the most accurate. So what is the largest AD-measured star? Wittkowski et. al. (2017) gives 1575 +- 400 Rsol for V766 Centauri A/HR 5171 A, making HR 5171 A the largest star known with a reasonably well defined radius.
Again, take the time to look at the spreadsheet I linked. If you have any questions, you can easily PM me.