Why Do Variable Stars Like R Hydra Exhibit Unique Color Changes?

[juan avellaneda]

hi all
I remember that once i see through a telescope a variable star ( i think it was R hydra) and it sees dark orange , why is that ? And is there some theory that explain this bizarre behaviour ?
I read once in an russian astrobook that the study of this stars will contribute to the progress in materials science .Are there real examples of this ?
And finally , can you provide me a website that show a photo of this stars at his minima and maxima??
tnx

 

[chroot]

Variable stars come in all different colors. There are actually a number of different mechanisms that can produce variation in luminosity.

Studying variable stars gives us information on the way stars work, which gives us information on the way nuclear fusion and fluid dynamics and so on work.

As far as photographs, I'm not sure. Most astronomers would have little use for raw photographs, and would prefer to look at a compiled graph, called a "light curve," that shows the star's luminosity as a function of time.

- Warren

 

[Nereid]

Mira, the wonderful

Here is a direct image of Betelgeuse , taken with the Hubble Space Telescope, and here is one of Mira. Both are red, and Mira is a very well known variable.

AAVSO, the American Association of Variable Star Observers - which, despite its name, is international in its scope - is an excellent source of information about variable stars, especially for beginners and amateurs.

 

[juan avellaneda]

Betelgeuse

im looking at the great Betelgeuse picture
im wondering if the bright yellow region is the internal core of the star?? or
everithing is just superficial
so we need to see this picture in 3D ?

 

[Nereid]

im looking at the great Betelgeuse picture
im wondering if the bright yellow region is the internal core of the star?? or
everithing is just superficial
so we need to see this picture in 3D ?

The image is a little fuzzy, because the HST is being pushed to its very limits in terms of resolution. The colours are not real; the colour of Betelgeuse is the same as you'd see it in a defocussed image of the star in a medium-sized amateur telescope, white with a reddish tinge. The only part of the star imaged is its photosphere, the same as the 'visible surface' of the Sun. As the caption says, part of the photosphere (just off-centre) seems to be a bright hotspot. Note that this picture was taken in the UV part of the spectrum (255nm and 280nm, bandwidth 30nm).

 

[juan avellaneda]

image

let me guess... the limit of the star is the medium size yellow circle in this picture, and the red part is the outer atmosphere??
but the "circles" are very concentric, first red,then orange,yellow to almost white... that was that suggest me the 3D interpretation
anyway is a nice picture