Friday, February 24, 2017

Discovery of exoplanets: Can there be life in Trappist-1?

Recreation of the new solar system with seven planets like Earth. A NASA telescope Seven terrestrial planets orbiting around a soft and quiet sun, at suitable distances, so that there is liquid water in them. The panorama can not be more optimistic for Trappist-1 (it is always better that name than its official name of 2MASS J23062928-0502285) can shelter the first sign of life outside our planet.

But things may not be so favorable. First, the distance of those planets to their star is very small. Of course, much lower than the one that separates us from the Sun. Suffice it to say that one year of the most interior planet lasts only one earth day.

Trappist-1 is a red star much colder than the Sun. Therefore, the closeness of its planets ensures a temperature tolerable and compatible with the existence of water in liquid state. That is good. But the same closeness makes them more likely to be blocked by tidal forces, always presenting the same face to their star, as does the Moon with the Earth. Or like most satellites of Jupiter or Saturn. That's bad.

And it is bad because it would entail tremendous temperature contrasts: One face of the planet always illuminated and warm, while the other would be in perpetual darkness. The only habitable zone would be the intermediate one, a more or less narrow strip between night and day. Although it would not be pleasant to live there either because the thermal differences between one hemisphere and another would probably cause hurricane winds.

That, not to mention that Trappist-1, like most red dwarf stars emit from time to time intense flashes of radiation that would reach fully to planets so close. It would be necessary for these to be protected by a magnetic field and a moderately dense atmosphere, such as Earth.

When the new telescopes (space and also on land) come into service, it will be possible to try to analyze the composition of these atmospheres. The mere fact that they exist would be good news. And if traces of methane or oxygen are detected in them, even in minute quantities, the arguments for life would be greatly reinforced. Not because tiny traces of oxygen were breathable but because their mere presence would mean that something is producing it.


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