Scientists Shift Search for Alien Technological Civilizations to Ancient Red-Dwarf Stars –“Twice Age of Earth”





“Red dwarfs – the dim bulbs of the cosmos – have received scant attention by SETI scientists in the past,” SETI Institute engineer Jon Richard said last week in a news release announcing the initiative. “That’s because researchers made the seemingly reasonable assumption that other intelligent species would be on planets orbiting stars similar to the sun.”

“This may be one instance in which older is better,” said astronomer Seth Shostak of California-based SETI, a private, non-profit organization which stands for Search for Extraterrestrial Intelligence. “Older solar systems have had more time to produce intelligent species.” A super-Earth known as Kapteyn b that orbits an 11.5 billion-year-old red dwarf, for example, makes the star and the planet 2.5 times older than Earth (image below). 

The srtistic representation shows the potentially habitable world Kapteyn b with the globular cluster Omega Centauri in the background. It is believed that the Omega Centauri is the remaining core of a dwarf galaxy that merged with our own galaxy billions of years ago bringing Kapteyn's star along. (PHL @ UPR Arecibo, Aladin Sky Atlas).




The SETI Institute belives that planetary systems orbiting red dwarfs — dim, long-lived stars that are on average billions of years older than our sun — are worth investigating for signs of advanced extraterrestrial life. The star that’s closest to our sun, Proxima Centauri, is a red dwarf. A variety of observing efforts, including Cornell's Pale Red Dot initiative, are looking for habitable planets around Proxima Centauri (shown above).

The two-year project involves picking from a list of about 70,000 red dwarfs and scanning 20,000 of the nearest ones, along with the cosmic bodies that circle them using the SETI Institute’s Allen Telescope Array in the High Sierras of northern California, a group of 42 antennas that can observe three stars simultaneously.

“We’ll scrutinize targeted systems over several frequency bands between 1 and 10 GHz,” said SETI scientist Gerry Harp. “Roughly half of those bands will be at so-called ‘magic frequencies’ — places on the radio dial that are directly related to basic mathematical constants. It’s reasonable to speculate that extraterrestrials trying to attract attention might generate signals at such special frequencies.”

For a long time, scientists ruled out searching around red dwarfs because habitable zones around the stars are small, and planets orbiting them would be so close that one side would be constantly facing the star, making one side of the planet very hot and the other quite cold and dark.

But more recently, scientists have learned that heat could be transported from the light side of the planet to the darker side, and that much of the surface could be amenable to life.

“In addition, exoplanet data have suggested that somewhere between one sixth and one half of red dwarf stars have planets in their habitable zones, a percentage comparable to, and possibly greater than, for Sun-like stars,” said the statement.

The brightest of Red Dwarfs are a tenth as luminous as the sun, and some are just 0.01 percent as bright, but account for three-quarters of all stars, with 6 percent or more of all red dwarfs having potentially habitable, Earth-sized planets.

The Daily Galaxy via SETI Institute, and AFP

Image credits: NASA/Chandra X-Ray Space Observatory

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