SETI Expands Hunt for Extraterrestrial Life to 20,000 More Star Systems

Alien Life
Thursday, 31 March 2016 - 11:17AM

SETI just expanded its search for intelligent aliens in a big way. Over the next two years, a new initiative will search 20,000 star systems that have been neglected by astronomers in the past: the exoplanets surrounding red dwarf stars.

"Red dwarfs – the dim bulbs of the cosmos – have received scant attention by SETI scientists in the past," SETI engineer Jon Richards said in a statement. "That's because researchers made the seemingly reasonable assumption that other intelligent species would be on planets orbiting stars similar to the Sun."

Red dwarf stars are generally not as bright as stars like our Sun, which made astronomers believe that habitable planets were highly unlikely to exist in these star systems. If the star is dimmer, then the habitable zone is necessarily both narrower and closer to the star. As a result of the close proximity, any planet in the habitable zone may become tidally locked, or would stop rotating and have one side permanently facing the star, which would make the temperatures on both hemispheres too extreme for the evolution and persistence of life.

But according to new research, red dwarfs may be perfectly adequate Sun substitutes. Recent studies have shown that between one-sixth and one-half of red dwarfs have planets in their habitable zones, which is comparable to Sun-like stars. Furthermore, we now know that if the tidally locked planets had oceans and an atmosphere, then a significant amount of heat would be transferred from the light side to the dark side, which means part of the planet would be habitable.

SETI astronomer Seth Shostak also explained that it is easier to observe red dwarfs, because there are more red dwarfs that are close to our solar system:

"Significantly, three-fourths of all stars are red dwarfs," said Shostak. "That means that if you observe a finite set of them – say the nearest twenty thousand – then on average they will be at only half the distance of the nearest twenty thousand Sun-like stars."

There's even a chance that red dwarfs could be better candidates for hosting habitable planets than Sun-like stars. Red dwarfs burn much longer than Sun-like stars; on average they burn longer than the current age of the universe, and every single red dwarf that ever existed is still burning today.

"This may be one instance in which older is better," Shostak said. "Older solar systems have had more time to produce intelligent species."