Intelligent life in our Milky Way Galaxy may have gotten a gigantic head start, say astronomers who confirmed the detection of low-mass, rocky planets around a star thats at least 11.2 billion years old, or more than twice the age of our own solar system.
In a paper just submitted to The Astrophysical Journal, an international team of University of Birmingham (U.K.)-led astronomers detail observations of KOI-3158, a pale yellowish-orange star that lies some 117 light years away in the constellation of Lyra. The team analyzed data from NASAs Kepler Space Telescope which revealed that this ancient metal-poor star harbors five terrestrial-mass planets whose origin dates back to the dawn of the Milky Way.
The implications of finding terrestrial-type planets around such an old, metal-poor star may be staggering. If life evolved on planets so early in the history of our galaxy, it would have already had at least 10 billion years to potentially vector into intelligence. By comparison, our own Sun is only 4.56 billion years old, and microbial life on Earth has only been around for an estimated three to four billion years.
This is confirmation that earth-sized planets have formed throughout most of the galaxys history, Tiago Campante, an astronomer at the University of Birmingham (U.K.), and the papers lead author, told Forbes.
The Milky Ways galactic center as seen from the ESOs La Silla Observatory in Chile. Credit: ESO/A. Fitzsimmons
Indeed, these planets sizes and potential makeup seem eerily akin to our own inner solar system. The systems three intermediate planets are the size of Mars Mars and the outermost planet is slightly smaller than Venus, while the innermost planet is the size of Mercury. Using stellar photometry, Kepler looked for periodic dips in starlight due to transits of planets across the face of their stars. Thus, they were able to determine that these five new rocky planets orbit their parent star in less than 10 days; less than one-fifth Mercurys distance from the Sun. As such, they would be much too hot to be hospitable to life as we know it.
Even so, the teams findings will likely help precipitate a paradigm shift of how planet hunters and astrobiologists view terrestrial planet formation within the Milky Way.
During four years of observations, Kepler took data which allowed the researchers determined the stars age to high-accuracy. KOI-3158 itself is some 25 percent smaller and 700 degrees cooler than our own Sun; part of a triple star system in the Milky Ways thick disk a ancient stellar population that stretches several thousand light years above and below the plane of our galaxy. By contrast, the Sun lies in a thin disk that makes up most of the galactic plane.
Because the star and the planets are thought to form around the same time and from the same nebula, we assume that the age of star is a reliable indicator of the age of the planets, Travis Metcalfe, an astronomer at the Space Science Institute in Boulder, Colo., and one of the papers co-authors, told Forbes.
With an iron composition only a third that of Sun, Campante cautions that in terms of habitability, planets around such low-metallicity stars may have some real red flags. Campante wonders if their planets would have a magnetic field strong enough to protect it from charged particles and cosmic rays that would otherwise strip away these planets upper atmospheres?
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NASA Kepler Finds Milky Way's Oldest Known Earth-Mass Planets