Low Mass Stars May be Havens for Alien Life According to New Research

They’re small, dim, red or brown, and common across the galaxy. They’ll never go supernova like some of the larger stars in our galaxy, and never form a black hole. And unlike our sun, most will never explode into red giants. They’re also less bright than the sun and can’t be seen with the naked eye, so they’re not part of the splash of stars we see when we look to the skies at night. For all intents and purposes, dwarf stars seem like boring members of the interstellar family and up until a week ago, I’d barely given them a second thought. Then I saw a colloquium by astronomer Philip Muirhead, and he totally changed my mind.

You see, sometimes being boring is a good thing. In the case of dwarf stars, their humdrum nature also makes them great places for life. While we’ve yet to find definitive proof of aliens, or any extraterrestrial life at all (though there are tantalizing hints), such life may be common in quiet stellar neighborhoods. Why? Several reason.

First, as has been discovered recently with the help of exoplanet surveys, red and brown dwarfs appear to have an abundance of planets. In particular, astronomers like Dr. Muirhead have catalogued brown and red dwarfs with the help of data from NASA’s Kepler Mission. They found that such stars commonly have small terrestrial planets like Earth. At least 40% of red dwarfs in the milky way appear to have super-Earths, or large rocky planets, orbiting in the habitable zone of their star where liquid water can exist. Recent results have also shown that they frequently have more than one rocky planet. There may be many reasons for this, including a less violent stellar neighborhood, which is also good news for hunters of exotic life.

The author’s imagining of the Proxima Centauri system (based on a Hubble telescope photo). Proxima Centauri is a red dwarf with 12.5% the mass of the sun and two confirmed exoplanets, one of which is in the habitable zone. At 4.25 lightyears away, it is also a close neighbor.

Dwarf stars are essentially smaller and cooler, so there is less intense radiation coming from them and less of the dangerous high-frequency light that harms life (like UV radiation). However, all is not perfect — rocky planets in the habitable zone orbit closer to these stars, where they may still be hit by dangerous solar flares that can strip planets of their atmospheres. Orbiting closer can also mean shorter seasons and day night cycles, as closer planets orbit more quickly. One can imagine a summer that turns to winter in a matter of weeks or days for a slower elliptical orbit, or 4 seasons smeared into one relatively constant, mild experience for a faster circular orbit.

Worlds like this might be common. Red dwarfs are the most common stars in our galaxy — with numbers in the hundred billion range — which means that there are potentially tens of billions (or more) rocky planets around such stars alone, many in a region around their star that can support life. Cooler brown dwarf stars are also common and may host similar amounts of rocky planets, leading to researchers searching for signals of life in those systems as well.

All of this is a very exciting part of the quest to find alien life, especially with the Kepler mission discovering new planets all the time. The James Webb Space Telescope will also help, as it is slated to study young exoplanets and to look for atmospheres around potentially habitable planets. Soon, tons of new data will be coming in, and with it new revelations.

Personally, I find it interesting to imagine these worlds from the perspective of alien civilizations, or even future humans. Will they be full or life, or boring and rocky? Are they more like to be covered in lush forest, or dry deserts? If such planets are barren, maybe they’ll make ideal bases for interstellar civilizations instead — safe and easy pitstops on the way to nicer outposts. While we don’t know what (or who) we may find out there, the future of astronomy — and our galaxy — is an exciting thing, and will only get more-so in the coming years.



I’m a physics postdoc, writer, and photoshopper who likes to send cats into space.

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Ryan Walraven, PhD

I’m a physics postdoc, writer, and photoshopper who likes to send cats into space.