12 September 2019

“The objective in the field of exoplanets is to find Earth 2.0.”


Rafael Luque (Spain, 2017) wanted to be an archaeologist but an astronomy course he took as a child changed his path. The workshop was for adults and he asked his father to register in order to accompany him, so in the classes it was him asking the questions and he was the first to note down the astronomical observations. “That is where I fell in love”, states Rafael.

Last July, his name featured in the media in an important story: the discovery of a new and nearby solar system with three exoplanets, including one that may support life

Rafael Luque is carrying out his doctorate at the Institute of Astrophysics of the Canary Islands thanks to a “la Caixa” fellowship and he played an important role in this finding by leading the team of seventy astronomers from seven different countries who worked on this study.

 

And what happened after this astronomy course?

After the astronomy course I took in my town, I became friends with the instructor. He had nobody to go out with to use his telescope so I joined him and he introduced me to the world of observational astronomy. At that time I was in high school, I was good at physics and decided to continue down that path.

In the last year of the degree at the University of Granada several classmates joined forces and we created a non-profit association (a “junior business”) focused on astronomy in order to organise school activities, workshops, observations of eclipses and night observations. 

Along the way I found a partner with a photography tourism company who was an astronomy enthusiast, so we mixed the two fields and the result was an astrotourism project that we carried out in Granada, and subsequently around all of Andalusia.  

You recently led the study into the discovery of a new solar system formed by a star and three exoplanets. What is an exoplanet?

It is a planet outside of our solar system governed by the same criteria as ours (planets around a star) but which does not orbit the Sun. 

Its closeness has been emphasised. Is thirty-one light years a distance that is really close to our solar system?

For the press and the general public it is very appealing to say that it is “nearby” because it opens up our imagination to a possible trip however now that is actually unfeasible.

The star in that system is a red dwarf, although this is the most abundant star in the universe, it does not emit much light. Scientists are really interested in stars that are close as possible, the closer the better because there is a higher chance of them shining more and having a good chance of being discovered, which is what happened this time. 

Also, the relative closeness makes it easier for us to measure the mass of the planets that orbit the stars using the technology we currently have and thus we gradually obtain information and data.

One of these planets seems to have favourable conditions for containing life. How are you able to predict what this exoplanet is like?

Right now we do not know if that exoplanet is or has been likely to contain life and we won´t find out for perhaps twenty or thirty years, but it is true that, at present, it is one of the best candidates for discovering it. 

The only thing we know is that it is in the so-called “habitable zone of its star” and we can assert that thanks to the calculations of geometry, distance and the energy that the star emits. We know that it emits a certain amount of energy and we deduce that the planet is a sufficient distance away so that, if it did have water, it wouldn´t be frozen or evaporate, but it may be liquid. 

This is not the case with the other two exoplanets which are closer to their star and thus receive temperatures that are too high.

In an article accompanying the discovery written by scientific colleagues from Cornell University in the United States, the study explains what the atmosphere of that exoplanet would have to be like in order to have liquid water. If it was similar to that of Earth and rich in carbon dioxide it could withstand enough heat to remain in a liquid state, but at the moment this is just a hypothesis.

What is the next step in this specific study? 

The immediate step is to confirm if this exoplanet in the habitable zone that we talked about in the previous question “transits” or not. Let me explain this. The starting point of the discovery was the observation, through a space telescope, of one of the two exoplanets closest to the star which dimmed its light when it passed in front of it. 

The “transit” means that is passes in front of the disk of the star from our line of sight from Earth, thus we detect how its light dims and darkens it. 

As the period of transit around the star of this exoplanet is longer that the observation time of the space telescope, we now need to use all the possible resources to calculate when this planet will transit and activate a campaign to look for its transit, detect it and view it.

If it is confirmed that it transits, it will become the transiting exoplanet in the habitable zone of its star closest to the sun. We are unaware of any system with these characteristics and that is why it is so interesting to scientists, because it would be the only one where we can study all of its properties.

The importance of this transit enables observation via a telescope which is the only technique we currently have to study its atmosphere and find out whether or not there is water on its surface.

Will the future of the discoveries depend on the technology that we are able to develop? What do we need to find out more?

The European Space Agency and NASA are working on new concepts of space missions for the 2030 generation and on, and although they seem like science fiction projects due to issues with budgets and engineering, the calculations indicate that in principle they will be feasible projects. 

We will need to send space telescopes in order to achieve a more complete observation and study and that will be the challenge of the next generation. 

With these new missions we would be able to study the closest planetary systems including a technique named coronagraphy. This method consists of blocking the light of the star that now blinds us in order to see the complete planets and carry out a light spectrum of their atmospheres and study their composition. That is to say, in a single step we would have access to everything, not like now where we have to take it step by step due to the technology available to us.

For you, what would be the most important discovery that you would like to participate in?

One of the objectives in astronomy is to find Earth 2.0. A planet with conditions similar to ours, around a star similar to the Sun and where we are able to measure the atmosphere and find signs of life.

The missions carried out from 2030 or 2040 on will focus on analysing the planets that are comparable to ours. It is a matter of looking for candidates in order to learn and we hope that, by following that path, we will end up finding a “twin”.

Will we find it?

I believe that all the missions will gradually converge until we achieve it. Right now, technology is limited, however it is a matter of a few years, when we have developed more advanced instruments, we will move closer to that discovery.

Personally, I believe that we will reach that day.

 

Photo "Carl Sagan Institute @CSInst / Jack Madden”