Credit: KU Leuven - Ludmila Carone
The search of habitable planet is often interpreted as the
search of an Earth twin, maybe we are looking it all wrong, and some rocky
planets outside the solar system may in fact be more promising.
Scientists from KU Leuven, Belgium, have run 165 climate
simulations for exo-planets that permanently face their sun with the same side.
They discovered that two of the three possible climates are potentially
habitable.
Most exo-planets orbits relatively small and cool stars
known as the red dwarfs. Only exo-planets that orbit close to their stars can
be warm to enough for liquid water. Being close to their star also make these
potentially habitable planets relatively easy to detect and observe for
research purposes.
Many exoplanets that orbit closely to their stars always
face their star with one side, meaning permanent day and night sides. Yet, the
climates on these planets is not necessarily scorching hot on one side and
freezing on the other. This is due to very efficient air conditioning system
that keeps surface temperature to habitable range.
Dr. Ludmila Carone, Professor Rony Keppens, and Professor
Leen Decin from KU Leuven, beligium, have now examined the possible climates of
these planets in unprecedented detail. “on the basis of 3D models, we examined
exoplanets with different rotation periods and sizes,” Ludmila Carone explains.
“We discovered that these rocky planets have three possible climates, two which
are potentially habitable.”
On exoplanets with rotation periods under 12 days, an
eastward wind jet known as superrotation forms in the upper layers of the atmosphere
along the equator. This wind jet interferes with the atmospheric circulation on
the planet, so its day side becomes too hot to be habitable.
The second possible wind system is characterized by two
weaker westward wind jets at high latitudes.
The third climate option combines weak superrotation with
two-high latitude wind jets.
The last two wind systems do not interfere with the air
conditioning system; so the planets remain potentially habitable.
The findings provide valuable input for future space
missions. Specifically, KU Leuven researchers are currently involved in
preparation of James Webb Space Telescope mission 2018---Hubble successor---as
well as planet finder mission PLATO 2024.
Not only will the study help identify the most promising
candidates for further research in our solar vicinity, it will also help avoid
premature discarding of potentially habitable planets that are worth
investigating despite un-earth like appearance.
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