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Tau Ceti System Doesn't Harbour Alien Life After All, Scientist Say

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Tau Ceti System Doesn’t Harbour Alien Life After All, Scientist Say

A team of astronomers at Arizona State University have poured cold water on the prospect of finding any intellignt life around the star Tau Ceti, one of the Sun’s closest neighbors and one of the most popularized systems in many science fiction works.

Tau Ceti, which is roughly 12 light-years away from Earth, has long been considered one of the first places to look for intelligent alien life due to its proximity to Earth and its star-like sun with many same characteristics as our sol.

Since December 2012, Tau Ceti became even more intriguing when astronomers found evidence of possibly 5 exoplanets orbiting the star, which two of them — Tau Ceti e and f — is thought residing in the “habitable zone” — not too hot or cold region of space, just-right range of distances that allow surface liquid water and potential life to exist.

But according to the new study, recently published in the Astrophysical Journal, the chance of complex life to flourish around Tau Ceti is very questionable. The ASU team’s used chemical composition of the star to model its evolution and to calculate the location of its habitable zone.

Planet e is in the habitable zone only if we make very generous assumptions. Planet f initially looks more promising, but modeling the evolution of the star makes it seem probable that it has only moved into the habitable zone recently as Tau Ceti has gotten more luminous over the course of its life.

Explains Dr Michael Pagano, ASU researcher & lead author of this new study.

Tau Ceti 's star system

Tau Ceti system ~ Click to zoom


 
Based on reseacrhers’ finding, planet f has likely been in the habitable zone for far less than one billion years. To put this into perspective, it took Earth’s biosphere about 2 billion years for life to emerge. The other three Tau Ceti worlds (b,c &d) are orbiting too close to their host star so they are likely too hot to harbor life. All Tau ceti planets are larger than Earth, planets e and f are 4.3 and 6.6 times more massive than Earth.

Additionally, Tau Ceti’s chemistry is different from that of our Sol. Tau Ceti has an odd ratio of silicon-magnesium (much more magnesium compared to silicon), this mean that Tau Ceti planets could be quite different from Earth.

It is possible that the mineralogical makeup of planets around Tau Ceti could be significantly different from that of Earth.

Said mineral physicist Sang-Heon Shim

Tau Ceti’s planets could very well be dominated by the mineral olivine at shallow parts of the mantle and have lower mantles dominated by ferropericlase.

Considering that ferropericlase is much less viscous, or resistant to flowing, hot, yet solid, mantle rock would flow more easily, possibly having profound effects on volcanism and tectonics at the planetary surface, processes which have a significant impact on the habitability of Earth.

Tau Ceti has been a popular destination for science fiction writers and everyone’s imagination as somewhere there could possibly be life, but even though life around Tau Ceti may be unlikely, it should not be seen as a letdown, but should invigorate our minds to consider what exotic planets likely orbit the star, and the new and unusual planets that may exist in this vast universe.

 

 

  • Journal reference: http://goo.gl/2vzmZ5.



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