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Dr Giovanna Tinetti

 

Giovanna Tinettu is an Italian astrobiologist and astrophysicist interested in the spectral retrieval and observations of exoplanetary atmospheres.  Gio works in the physics department at University College London but is also a regular collaborator with the ESA and NASA.

What I think is amazing today is to be able to probe so far away in time

On getting interested in science

I started to be interested in science when I was ten.  This was in part because I had an excellent math teacher at school and she kept encouraging me in trying to find solutions to problems and that was really inspiring to me.  And she was giving me excellent books about physics and, ah, I really got quite obsessed about the physics of atoms and I really wanted to study physics.  Originally I started with particle physics because this was really my main interest but then when I was doing my PhD in Italy I started to be very interested about this completely new field which was exosolar planets.  It was something that was very new because the first exosolar planet was first discovered in 1995 only, so it was a brand new field and nothing was known and I thought it was so exciting to jump in a field where you could be among the first people to look into some problems and try and address those.  And so that’s how I switched field and I went to the United States and started a slightly different career in astrophysics instead of physics, so it is not such a big jump but certainly  that’s how my adventure started.

When I started to work on exosolar planets, this field was just really starting and it was literally a big bet so when I started to say to my senior colleagues that I wanted to go to the States and work on this completely new field they were very cautious and they tried to suggest to not necessarily make this big change.  And I can understand their point, but when you’re young and you’re very excited about something you just want to try it and so that’s what I did.

Sometimes I go back with my mind and I think about when I was ten and I really wanted to be a scientist – and I come from a small town in the Alps so as you can imagine it’s not a big city like London where now I live – and I had this childhood dream of becoming a scientist and I still remember that, although encouraging, my parents always thought that it was a childhood dream and I shouldn’t really, probably, dwell too much on that and probably would try to be protective with me and not having me, you know, take too many illusions.  And sometimes I look at my life right now, living in London, which is a big city and I always dreamed I would live in a big city, and I’m doing the job that I really dreamed of.  So I’m very happy about this and hope that more young people are trying their own dreams and they’re not listening to too much skepticism that sometimes is coming from people that be more senior or more adult, also, more cautious, but sometimes you just need to try and try your own dream.

On working as an astrobiologist

I work in exosolar planets, I work in, physically, University College London.  My work is looking at planets that are orbiting stars different from the sun and what I do, day by day, is basically to model their atmospheres and try to understand what kind of chemical components might be in those far away atmospheres and then match these models with the very few observations we start to have about these very exotic objects.

When an exosolar planet is discovered there is a…it is a very interesting object to try and characterise and know more about its properties and what it’s made of.  In some particular cases we can use a telescope to look at their chemical components in the atmosphere and the way we do so is to focus on planets which are transiting, so at a certain point passing in between the star and the observer and when the planet is transiting in front of the star we can basically measure the light of the star which is filtered through the atmosphere of the planet and look at this light decompose at different frequencies and extract the details of the chemical components by literally looking at the signature, the spectral signature, of this molecule in the spectrum.  And so, after the observation, ah, we need to do a bit of work to try to extract the signal because it’s a very challenging type of observation, looking at accuracy of one part in ten thousand compared to the light coming from the star so it’s a very, very challenging type of effort.  And then we do models looking at what kind of molecules it’s containing in the spectrum so we are trying to match some databases where we have the information of the signature of different molecules with these spectra and try to understand whether that specific molecule is contained in these observations.

And we have been quite successful in doing this for many planets now with space telescopes like Hubble and Spitzer.  We were able, for instance, to discover the presence of water vapour and carbon dioxide and monoxide and methane in many of these gas giant planets that are orbiting very, very close to their stars.  And now this kind of technique is being used to sound also the atmosphere of planets which are more similar to the Earth, so smaller and also colder, with respect to where we start from, and ideally one day we can do this for planets which are even more similar to the Earth and probably also have habitable conditions.

On making discoveries

Luckily I started to work on the atmospheres present in the solar system and so I could learn a lot of the techniques being used for planets in the solar system and also satellite data for the Earth and that gave me a very good basis to then start thinking about what sort of observation one wants to do when you want to probe the atmospheres of planets that are very far away.  And, to me, when transiting planets became more numerous and…for transiting planets I mean planets that at a certain point are transiting between the observer and the star and so you can use this dip in the light of the star to detect the planet.  To me, then, the obvious way to probe these atmospheres was to use infrared light rather than light in the visible.  Infrared is important because that’s where most of the molecules have a very strong signature and so if you want to probe molecules like water vapour or methane or carbon monoxide you really want to use the infrared as a way to…as a good diagnostic of these atmospheres.  And so I tried to think how to do that for exosolar planets and I thought that combining the technique of transit, and this was already done successfully but in our wave lengths, to the infrared was the good way of doing things.

In 2007, with collaborators from the UK and France and the US we tried some observations with Spitzer that gave us the first discovery of water vapour in one of these exosolar planets so that was a quite exciting moment. 

What I think is amazing today is to be able to probe so far away in time, in the past, and looking really at the few first moments of the universe and to me it is quite extraordinary to see that nowadays, observation can literally probe the time which is very close to the Big Bang, the starting of everything.  I think it’s an amazing concept that today science can go back so far away and look at the origin of everything or at least very close to that is just something that… [she is simply speechless at the thought]

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