Chuck Bednar for redOrbit.com – Your Universe Online
Astronomers have discovered the oldest known planetary system ever – a star that is more than 11 billion years old and orbited by at least five rocky planets that are all smaller than Earth.
The discovery, which came following an in-depth analysis of over four years worth of data from NASA’s Kepler space telescope, could indicate that Earth-sized planets have formed throughout the nearly 14-billion-year history of the universe, those researchers claim.
Furthermore, the findings increase the possibility of the existence of ancient extraterrestrial life, and could even indicate that advanced intelligent life exists somewhere in the cosmos, according to Nancy Atkinson of the website Universe Today.
In a paper accepted for publication by The Astrophysical Journal, Dr. Tiago Campante from the University of Birmingham School of Physics and Astronomy and colleagues report observations of an ancient, metal-poor, Sun-like star known as Kepler-444, which is about one-fourth the size of our sun and is located 117 light-years from Earth.
Kepler-444 is at least 11.2 billion years old, or 2.5 times older than Earth, and orbited by at least five planets with sizes between those of Mercury and Venus, BBC News noted. The planets take approximately 10 Earth days to orbit around the star, and while they are too close to their sun to support life, their discovery indicates that planets close to the same size as Earth (and capable of supporting life) could theoretically exist around stars equally as old.
Dr. Campante told the BBC that the discovery could provide clues to the “existence of ancient life in the galaxy. By the time the Earth formed, the planets in this system were already older than our planet is today. This discovery may now help to pinpoint the beginning of what we might call the era of planet formation.”
“The fact that rocky planets were already forming in the galaxy 11 billion years ago suggests that habitable Earth-like planets have probably been around for a very long time, much longer than the age of our Solar System,” Dr. Travis Metcalfe, one of the researchers involved in the study as well as a senior research scientist at the Space Science Institute, told Universe Today.
Dr. Metcalfe added that while the star is slightly cooler than the Sun, with a surface temperature of 5000 Kelvin compared to the Sun’s 5800 Kelvin, the planets in the system were believed to be highly irradiated with little to no atmosphere, rendering them inhospitable to life. Even so, all of the planets orbiting it fall within its habitable zone (0:47 AU from the parent star).
“This is one of the oldest systems in the galaxy,” said co-author Steve Kawaler of Iowa State University. “Kepler-444 came from the first generation of stars. This system tells us that planets were forming around stars nearly 7 billion years before our own solar system. Planetary systems around stars have been a common feature of our galaxy for a long, long time.”
What makes the discovery even more amazing, according to Forbes contributor Faye Flam, is that until recently, scientists weren’t even sure that planets could have formed this early in the history of the universe. The reason is due to the fact that only hydrogen, helium and lithium existed immediately following the big bang. The other elements formed later, inside stars, and were spread throughout the universe when those stars died in supernovae.
“From the first rocky exoplanets to the discovery of an Earth-size planet orbiting another star in its habitable zone, we are now getting first glimpses of the variety of Galactic environments conducive to the formation of these small worlds,” the authors of the new paper wrote. “As a result, the path toward a more complete understanding of early planet formation in the Galaxy starts unfolding before us.”
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