Blue Super-Giant Stars!

[YNM]

@PB666 Actually, as you should read out, HD 140283 is only an F3 star; it's not blue, it's only a little bit hotter than the Sun. Blue stars would be of O/B classification, A0 star by definition is white (or rather, "white").

[PB666]

40 minutes ago, YNM said:

@PB666 Actually, as you should read out, HD 140283 is only an F3 star; it's not blue, it's only a little bit hotter than the Sun. Blue stars would be of O/B classification, A0 star by definition is white (or rather, "white").

F3 is ranges from white to blue white.

https://en.wikipedia.org/wiki/Stellar_classification#/media/File:HR-diag-no-text-2.svg

If it were any bluer it age would not be approaching the age of the universe .

I think we are missing the point. Lets go back and try this again, Life does not exist around unstable stars for any number of reasons, you can wipe all these stars from the discussion as every single last one of them are impertinent. The triangulation is how to create bluer stars that are stable and last at least a billion years in age. Its easy to get a 10 billion year plus red star. Its not easy at all to get a blue star that is long lived

Class 0  1 in 3,000,000  Short lived and associated with star forming clouds
Class B  1 in 800 Short lived and associated with star forming clouds
Class A  1 in 160  are longer lived are hydrogen rich but also have notable Fe , Mg, Si 
Class F  1 in 33 stars
These stars represent only 1/26th of the stars in our local neighborhood.
If we talk about stable stars over a billion years in age the list stops essentially with F.

Most blue stars die within a few million years. The way to make them live longer is to decrease their metallicity but also decrease the likelihood of core formation. It has to be remember that supernova do not occur because a star burns all its hydrogen, simply, but has enough elements in the carbon-iron range to begin core formation and core collapse. The heavier metals in its structure can aid in core accretion within a stars very volatile structure. Population 1 stars and early population 2 stars must wait until surrounding eject for the SN size threshold to decrease to average modern levels. It buys time for these stars. Since these stars have to wait until formed and blasted their direction its very difficult for them to form iron.

The problem is that in the current stellar nurseries the density of hydrogen is simply too low to form long lived blue stars. T0 get an environment that allows that you have to go backward in time to a period when the density of hydrogen in the universe was 1000s of time higher.

Population III stars

" One theory, developed by computer models of star formation, is that with no heavy elements and a much warmer interstellar medium from the Big Bang, it was easy to form stars with much greater total mass than the ones visible today.^{[citation needed]"}    

^I translate this as meaning it was much more difficult to form smaller stars and certainly not planets. The heat of gas means that the critical mass required for accretion and density facilitates that accretion.

"Typical masses for Pop  III stars are expected to be about several hundred solar masses, which is much larger than that of current stars." " Stellar Population" - wikipedia.

Theory belies the observation since the intense blue stars anticipated as population III and early population II stars is absorbed during reionization and thus most are difficult to observed and refutable. The computer models predict that early star formation required 100 to 130 solar masses of hydrogen, whereas these sized stars represent the extreme heavy end of the current spectrum.

These stars are largely not visible, even when red-shifted toward the CMBR limit because at the time of their formation and for considerable periods thereafter there was too much gas in space.

 

[YNM]

5 hours ago, PB666 said:

F3 is ranges from white to blue white.

https://en.wikipedia.org/wiki/Stellar_classification#/media/File:HR-diag-no-text-2.svg

If it were any bluer it age would not be approaching the age of the universe .

I think we are missing the point. Lets go back and try this again, Life does not exist around unstable stars for any number of reasons, you can wipe all these stars from the discussion as every single last one of them are impertinent. The triangulation is how to create bluer stars that are stable and last at least a billion years in age. Its easy to get a 10 billion year plus red star. Its not easy at all to get a blue star that is long lived

Class 0  1 in 3,000,000  Short lived and associated with star forming clouds
Class B  1 in 800 Short lived and associated with star forming clouds
Class A  1 in 160  are longer lived are hydrogen rich but also have notable Fe , Mg, Si 
Class F  1 in 33 stars
These stars represent only 1/26th of the stars in our local neighborhood.
If we talk about stable stars over a billion years in age the list stops essentially with F.

... And there, you have the point.

The term "blue giants" refers to stars with a values of B-V and U-B of less (or close to less) than 0, and having a large luminosity such that it's a lot brighter than the main-sequence one would be. By definition, these stars are of O-B spectral types. Henceforth, there's simply no way to have a habitable kind of them.

That's it.

An A, F, or G supergiant would be yellow.