We may be one step closer to finding a “second home” for humans, thanks to research conducted by an international team of astronomers. By observing wobbles in Tau Ceti, a sun-like star 12 light years away, scientists discovered that four Earth-sized stars are orbiting it. Two of the planets have masses as low as 1.7 Earth mass (which is rare), while the other two are super-Earths — meaning they could potentially support life.
To monitor the wobbles of the sun-like star, the team employed techniques sensitive enough to detect variations as small as 30 centimeters per second. “Our detection of such weak wobbles is a milestone in the search for Earth analogs and the understanding of the Earth’s habitability through comparison with these analogs,” said lead author Fabo Feng, from the University of Hertfordshire in the UK. “We have introduced new methods to remove the noise in the data in order to reveal the weak planetary signals.”
While the outer two planets around tau Ceti are the right size to be habitable worlds, massive amounts of debris around the star likely reduce their habitability due to the intense bombardment of comets and asteroids. Nonetheless, the discovery is an exciting one.
“We are now finally crossing a threshold where, through very sophisticated modeling of large combined data sets from multiple independent observers, we can disentangle the noise due to stellar surface activity from the very tiny signals generated by the gravitational tugs from Earth-sized orbiting planets,” said co-author Steven Vogt, professor of astronomy and astrophysics at UC Santa Cruz.
Mikko Tuomi, from the University of Hertfordshire, added, “We are slowly learning to tell the difference between wobbles caused by planets and those caused by stellar active surface. This enabled us to essentially verify the existence of the two outer, potentially habitable planets in the system.”
The team wrote that sun-like stars are believed to be the best targets for finding habitable Earth-like planets. Tau Ceti is, indeed, very similar to our solar system’s Sun in both its brightness and size. Additionally, both stars host multi-planet systems.
The research was published in the Astrophysical Journal and is available online.