Angry Little Stars Could Produce Life-Friendly Exoplanets

Red dwarf stars may be able to support habitable exoplanets after all -- through complex tidal interactions between star and planet, global magnetic fields could evolve, protecting hypothetical life forms from the red dwarfs' ferocious nature.

Once identified as the perfect place to search for habitable exoplanets, in recent years, the life-giving reputation of red dwarf stars has taken a downturn. Sure, red dwarfs are abundant in our galaxy and we've spotted many with planetary systems, but the environment surrounding these tiny stars are generally considered to be a bad place for alien life to set up home.

For starters, red dwarfs are much smaller and therefore dimmer (and cooler) than our sun, so the distance a hypothetical "Earth-like" planet would need to orbit the star is much closer than the distance at which the Earth orbits the sun. The "habitable zone" -- the region surrounding a star that isn't too hot nor too cold for water to persist in a liquid state on that planet's surface -- is more compact around red dwarfs, creating a host of problems.

Although small, many red dwarfs observed are known as "flare stars" -- basically angry little stars that generate powerful flares, drenching any nearby planets in powerful doses of radiation. These savage stellar storms, including powerful stellar winds, will likely sterilize any habitable zone planet, ensuring they remain uninhabitable (for biology as we know it in any case). In addition to the horrible stellar weather, planets orbiting within a red dwarf's habitable zone will likely become "tidally locked" with the star; one hemisphere will always be sun-facing, whereas the far side will be in perpetual darkness.

Loners. Particularly weird loners with unpronounceable names. Carrying an axe. Hitchiking . Yep, that's scary -- a storyline that has been used for generations to scare the pants off cinema-goers. So, what about loner exoplanets? There are thought to be loads of exoplanets out there, but a few of them are too small and too distant from their host stars to be detected by conventional telescopes. However, sometimes, astronomers get lucky and spot one of these extra-solar loners. Take MOA-2009-BLG-266Lb for example. (Sounds like a weirdo, right?) It's a "super-Earth" that would normally orbit its star too far away to be spotted. But, with the help of general relativity, its 10-Earth mass bulk bends spacetime just enough to focus its star's light when seen from Earth. This is known as a "microlensing" event, and though rare, it can pick out tiny rocky worlds floating far from home. And then there's the case of PSO J318.5-22 (pictured here) -- a free-floating exoplanet that appears to have lost its parent star all together. But then again, it might not be a planet at all, more of a "failed star." That moniker shouldn't give this lonely guy self esteem issues at all... These exoplanetary loners may not be carrying an axe, but they do pose many questions as to how they evolved so far away from their stars (if they had stars in the first place, that is). [V. Ch. Quetz/MPIA]

What I find surprising is how emotionally invested NASA scientists are in finding life. I guess it helps their funding.

But what if there isn’t life out there?

In this vast universe we may be alone.

That is what would be mind blowing.

Huzzah!

I get astronomy which I love, and Red Dwarf, which is one of my top three all time favorite TV shows in one thread.

This is a very very good day. A good day indeed.

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