So I'm working on a world that orbits a blue star that's not much bigger (or even smaller) than the sun. I was thinking that an A-type star would be a good choice for it, but it's still is closer to white than blue. Is there any way for the conditions of an A-type star to be just right to give it a bright blue glow?
Here are your color options:
If you can get your star past infinite temperature, then you can have it be a nice blue rather than blue-white. A more feasible option is to make the star appear blue due to the atmospheric composition. Or, if something else needs to budge, you'll need to make it the largest type A you can (about 2.6 solar masses) and it'll be just between blue-white and deep-blue-white
But, basically, a bluish-whitish is the most likely outcome. For a human observer, at least.
I see one serious problem - time scale.
Solution I - you use high concentration of handwavium to explain why it was possible to form planet and interesting enough life on such planet so fast. As an excuse I could imagine UV light splitting water, causing hydrged to escape and oxygen to accumulate, thus speeding up local great oxygenation even that allowed multicelluar life.
Solution II - blue dwarf - just wait The only problem that the universe is clearly to young for them and they are just predicted late phase of small red dwarfs. If your story can wait so much... Then you may use it. http://beyondearthlyskies.blogspot.be/2013/09/blue-dwarfs-stars-yet-to-be.html
Solution III - blue dwarf - lucky coincidence After a series of nearby supernovas (? not 100% sure how to get such composition, it may also involve serious amount of handwavium) a tiny star was formed with ultra high helium concentration, hundred of billion of years before their time, looking more or less like a blue dwarf.
The light given off by a blackbody spectrum at high temperatures like those found in stars, once you get above the temperature of the Sun's photosphere, which is around 5700 K, is going to be practically indistinguishable from white.
The first thing I thought of when it comes to this is absorbing the light coming off from the star. But any amount of dust between the star and the planet would get blown away over the course of a few thousand years.
I'm thinking you want something like this though.
The rings around the stars are actually optical defects, so I'll ignore that. But the thing which makes the entire area blue is not anything to do with the stars. Rather, it has to do with the dust which reflecting the blue light coming off from the star itself.
This, due to radiation pressure from the star, cannot last for long, but like the Pleiades, the stars could be travelling through a particularly dusty region of the galaxy which provides the dust necessary to explain such scattering.
Secondarily, one should also note that this solution wouldn't make the star blue (it would still be blue-white). But rather, it would make, for a planet inside the cluster, the entire sky have a faint blue glow.
If the sky were red rather than blue, might our sun look blue by physiological or neural colour-contrast effects? I'm not sure.
Anyway you can't get a red sky by scattering off dust because short wavelengths scatter more strongly than long. Hence blue sky. But suppose plants on this planet had evolved hydrogen bladders, and a different photosynthesis to Earth that worked on blue and green but not red? Then plant life would be red not green, and because of airborne plants the sky would also be reddish.