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Of course it's very obvious that blue stars are insanely hot and would boil away most things if they got too close. BUT I'm curious if with just the right adaptations and fiddling, could there, theoretically, be a way for life and water to exist on a planet orbiting a blue star? Perhaps if the planet is far enough and certain conditions are miraculously met, like ways to combat the intense UV rays emitted and the brutal heat for example.

If you need me to clarify anything, let me know.

Edit: I forgot to point the short span. Since we're already bordering on fantasy anyway, let's assume somehow, someway, a blue star was sustained long enough for life to form. I know this is really, REALLY stretching the suspension of disbelief, but I'm really curious about the quality of the possible life on a blue star planet and how far we can make it plausible.

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    $\begingroup$ Put the planet far enough away? The light would still be weighted toward the high energy but distance deals with a lot. $\endgroup$
    – Mary
    Jan 20, 2023 at 13:16

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The biggest issue with a life suitable planet around a blue star is the short life time of blue stars. This gives a life time of 10 to 100 million years for different kinds of blue stars. That may be just enough to form planets and have their crust cool down enough to solidify if they are at a suitable distance from the star. But it seems way too short for any life to naturally develop on these planets.

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  • $\begingroup$ Since the question is explicitly allowing far-out solutions, wouldn't a blue star capturing a rogue planet (maybe even one already having organic chemistry developing before it got kicked out of another solar system) a solution to the crust-cooling problem? $\endgroup$
    – Jedediah
    Jan 20, 2023 at 15:23
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    $\begingroup$ @Jedediah That could get around the crust cooling, but it still appears to have taken several hundred million years of Earth having liquid water for life to appear...just non-photosynthetic single-celled life. In 100 MY "Blue Star Lifetimes", Earth took about 3-4 BSL's from "first liquid water" to get to single celled life, 9 BSLs to photosynthesis, and about 28 BSLs to the formation of multicellular life. This planet would need to progress 10 times faster just to have green slime and 20 times faster to actually have oxygen in the atmosphere by the time the blue star is dying. $\endgroup$ Jan 20, 2023 at 15:37
  • $\begingroup$ Of course, Earth is a sample of one, and we have no idea how representative it is or how widely such things vary, but from what we do know it would at least be quite surprising to find life on such a planet. $\endgroup$ Jan 20, 2023 at 15:43
  • $\begingroup$ @ChristopherJamesHuff The limit is shorter than the lifespan--habitable zones move outward as stars age. The sun is halfway through it's main sequence life--but 80% of the habitable time on Earth is up, more like 99% if you consider suitability for things with long life cycles. $\endgroup$ Jan 21, 2023 at 1:07
  • $\begingroup$ You also have a big problem with the capture approach--captures are almost never into circular orbits. Circularization won't happen fast enough and without it the planet is awfully inhospitable. $\endgroup$ Jan 21, 2023 at 1:09
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I'll disagree with the other answers and say that the short lifespan of blue stars does not necessarily mean that there isn't time for life to evolve, just that conditions on the world would have to be just right for life to evolve before the star reached the end of its main sequence lifespan, and those conditions would also necessarily dictate the character of life on such worlds.

This would mean that we need life that lives fast, to minimise the time between generations and increase the speed of evolution.

Since life is basically a self-sustaining set of chemical processes, the conditions necessary for faster chemical processes are effectively limited to higher temperatures. The world will need to be hotter than Earth, and the organisms themselves will need to run hotter than terrestrial life relative to the background temperature, so we'll have a hot world with hot-blooded creatures.

Given high metabolic rates and short generations, these creatures will have to live fast, even the autotrophs. They'll need to move fast and eat a lot in order to survive given their high metabolic rates, which would favour creatures with quick reaction times, quick movements, and short generations. When compared to humans, even the slowest of these creatures would seem fast, and the fastest might well be terrifyingly fast. They may also tend to be small, since the square-cube law dictates that smaller creatures require a higher metabolic rate in order to survive. Given the lack of time for life to evolve, I would expect bug-sized life forms that are fast and aggressive and reproduce soon and in great numbers. They would not likely be particularly intelligent, though that is not a certainty. They may well attack a human if a human was able to visit and would likely boast better speed and reaction times than humans and might have generation measured in mere days for higher life-forms and minutes for lower life-forms.

Given the necessary conditions, we'd expect a hot world, where any water was above 60°C, or maybe having a more exotic biosphere with a much higher temperature than that allowable to a liquid water biosphere.

Any world around a blue star with life would also likely be very close to the point at which the star leaves the main sequence, whether entering a helium-burning stage which will incinerate the world, or about to become a supernova.

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As a previous response from use @quarague mentioned, the stars you're looking at are very short-lived, such as B class, and even shorter, O class. If we suspend disbelief though over the time of development of a planet and the life on it or intend to terraform this planet, here's something to use.

The WorldSmith is a very, very useful tool by YouTuber Artifexian which consists of various calculators put together into a google spreadsheet in order to make fairly accurate, if somewhat simplified, calculations based on planetary factors. This includes things from the solar system, galaxy, planet itself, atmospheric composition, the moon and its effects, and so on so forth.

Anyways, the point is that under the Star category, you can customize the age and the mass, and from there, the sheet will automatically calculate the class, density, radius, luminosity, temperature, maximum age, and more importantly, the star's color (which is dependent on class), the habitable zone, and if an Earth-like planet could exist there.

Of course, if you want to use relatively hard science, the answer would be no. The star's life span is too short, and even if we ignore that, you wouldn't get anything like Earth, though I don't know what that would entail. Nonetheless, it might be possible, if you ignore time.

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