Discovering seven exoplanets the size of the Earth: “One more step for research”

Science 23 February, 2017

Vincent Coude du Foresto, an astronomer at the Observatoire de Paris, is pleased with the recent discovery of seven planets the size of the Earth by NASA. He explains on Thursday that it is possible that they shelter an atmosphere, even of life.

A system of seven planets the size of the Earth, three of which could harbor oceans of liquid water and therefore potentially life, was discovered by astronomers around a dwarf star, revealed a study Published on Wednesday in the journal Nature .

“This is a great news, a step further in a research that began almost 20 years ago ,” reacted Thursday 23 February on franceinfo Vincent Coudé du Foresto, an astronomer at the Observatoire de Paris. “We do not know if they are accompanied by an atmosphere, but hope remains.”

Franceinfo: Systems with several planets have already been discovered. What’s new this time?

Vincent Coudé: What’s special about this one is that the star around which these planets rotate is particularly small. If she had been a little bit smaller, she would not have been a “star” anymore, but would become a “brown dwarf”. These stars are called “red dwarfs” and are very common in the galaxy.

What is the characteristic of “red dwarfs”?

The small stars are much less warm than the Sun and much less bright than the sun. To be in the comfort zone, you have to get close to it. The zone of comfort around the Sun corresponds to orbits of one year. There, we have orbits of a few days, which makes the detection of planets much easier.

How were these planets discovered?

It is thanks to the technique of transits: we see the planet passing the star, which occult a little the light of the star. Its brightness decreases slightly and it reproduces itself very regularly, as the planets pass by. There are many reasons that can cause a star to see its shine diminish a little. But if this happens in an extremely regular way, we really have strong indicators of the presence of planets. Then there’s a whole bunch of tests to check that out.

Can three of these planets house life?

We will have to do additional investigations to find out. What we know is that they are in a place where it is possible. We have no idea what these planets look like. It is not known if they are accompanied by an atmosphere, but hope remains.