Are we still going to have rainbows if Sun is replaced by another star?
Rainbow is a property of light splitting due to the water molecule present in the clouds and is related to the light emitted by our Sun. Our sun is a yellow star. Now if we replace sun by a blue giant star or red giant star, or any other star of different color, are we still going to have rainbows? If yes is it still going to compose of seven colors? What kind of possible change will occurs, if any?
http://fas.org/irp/imint/docs/rst/Sect20/A7.html may or may not be helpful. It shows at what frequencies (colors) various stars emit light in comparison to the Sun. Scroll down to the Spica/Sun/Antares graph (the portion of the page above that doesn't really answer your question)
Note that our perception of a rainbow is based on the physiology of the eye, which adapted to the visible light on this planet. Had this planet another sun with a different spectrum, and evolution blessed humans evolving there with three different colour receptors, then you would certainly perceive any rainbow there just as colourful.
Rainbows would lack most blue, and some green for red stars.
For a blue star, the blue part of the rainbow would be more intense.
For more complex colors, the rainbow may show some gaps. A rainbow is essentially a spectrum of that star light portion, which is visible to our eyes, and to which the atmosphere is transparent.
Stars vary in brightness. A blue giant would be large and glaring, a red dwarf faint.
Colors in the rainbow would be blurred, hence closer to white, for large stars, and sharper, more distinct, for small stars, according to the angular size of the respective light source.
... This all assumes, that there is still rain. With small, red stars, it would get too cold for rain. With large blue stars, Earth would heat up too much.
To adjust for these effects, the distance to the star would need to be modified.
And of course, the length of a year, and the orbital velocity may change.
This could then cause different tides, changes in volcanism, etc.
Exchanging the star could cause various other effects, too, other polar lights, effects to the ionosphere, the ozone layer, atmospheric erosion, more...
Wouldn't the question of whether or not there is rain be a function of orbital distance? All stars have a "Habitable Zone" - though for some, it would be so close that the planet would be tidally locked.
Yes. Then we would need to do more than exchanging the star. Tidal locking would take some time, possibly accompanied by inundations, earth quakes, or more vulcanism, due to tides and tidal heating.
wait a minute, I thought stars are red or blue depending on their relative expansion speed to earth. replacing the sun would leave no relative speed so it makes no sense to speak of blue or red within one system does it ?
@v.oddou Check out https://en.wikipedia.org/wiki/Stellar_classification, particularly the section on Harvard spectral classification. You are confusing it with Doppler shift.