Is Betelgeuse really a red supergiant ?

[skysurfer]

In several articles, youtube clips and the largest online astronomy textbook is stated that the star has a large envelope of gas and dust around it.

Subsequent studies have reported an angular diameter (apparent size) ranging from 0.042 to 0.056 arcseconds, with the differences ascribed to the non-sphericity, limb darkening, pulsations, and varying appearance at different wavelengths. It is also surrounded by a complex, asymmetric envelope roughly 250 times the size of the star, caused by mass loss from the star itself. The angular diameter of Betelgeuse is only exceeded by R Doradus (and the Sun).

And, as we know, dust scatters and takes all blue light out of the light of a light source. E.g. remember the Sun shining red through smoke or dust ? Is Betelgeuse not the same: a bluish white Rigel-like supergiant star shining through this envelope scattering the blue light and leaving a red appearence ? And other red supergiants like VY CMa, VV Cep, Antares ? Of which the first two are as large as Saturn's orbit and should be sooooo tenuous, that they cannot have a photosphere. Is it here a dust envelope of which we measure the dimensions ?

I do not stat this is true, it is just a possibility I think.

What are your ideas ?

[sheeny (Al)]

Spectroscopically its a red giant. No doubt about it. The temperature matches the spectral lines for this type of star. There is nothing to indicate an mystery there.

Smoke and dust affect the colour of transmitted light due to their colour more than anything. Bushfire smoke is often brown, dust off red soil is of course red. Most of the blue scattering we obseve is due to nitrogen in the atmosphere. That is why you don't need dust or smoke in the air to get a red sunset (but of course they will help to make it spectacular).

Al.