From Molecular Clouds to Exoplanets

The past decade has been characterised by a huge interest in the study of low mass stars (stars as or less massive than our Sun), brown dwarfs (failed stars unable to sustain nuclear fusion but which form like stars) and exoplanets (planets orbiting around other stars than the Sun). Now, about 500 exoplanets have been yet discovered and many more are expected with the space mission Kepler or large surveys like the UK program Superwasp, making the field of exoplanet one of the fastest growing areas of astrophysics.
With the development of infrared telescopes and near-IR surveys, a wealth of data for low mass stars and brown dwarfs has also become available. Their study is particularly important in an astrophysical context, knowing that most stars in our Galaxy are smaller than the Sun. Major observational efforts are devoted to star forming regions and very young stars, providing the basis for a better understanding of the very early phases of stellar evolution and most importantly of the fundamental process of star formation. Despite great progress on the theoretical and observational fronts, many pending questions remain regarding the whole process of star formation, starting with the gravitational collapse and fragmentation of a molecular cloud. This produces embryos of stars (the so-called proto-star) surrounded by an accretion disk where eventually conditions for rocky terrestrial and gas giant planets formation are met. This picture shows that stars and planets share a common origin. They also share common physical processes which play key roles on their interior and atmosphere structures and on their evolutionary properties, like convection and magnetism. The studies of these two populations of astrophysical bodies are closely interrelated, not only in terms of formation process, but also in terms of physical properties.

We thus propose a consistent research programme devoted to the understanding of (i) star and planet formation, from the collapse of molecular clouds to the formation of proto-stars and proto-planets, and (ii) stellar and planetary physics appropriate for the description of stellar and substellar objects' interiors and atmospheres (solar type and low mass stars, brown dwarfs, exoplanets). This programme plans to address several key questions in these areas combining high quality observations with state-of-the-art theoretical calculations and modelling.
On the theoretical front, we plan to develop advanced numerical simulations to understand convective transport, dynamo generation and magnetism in low mass stars and brown dwarfs and to describe irradiation-induced dynamics in exoplanets. Regarding the formation of these objects, we will use state-of-the-art simulations to study the effect of radiative feedback on star cluster formation and the process of planet formation based on self-consistent models of the interaction between protoplanet and circumstellar disk. We will also address the question of triggered star formation by the most luminous members of a star forming cluster using sophisticated radiation hydrodynamics models.
On the observational front, pending questions regarding the properties of molecular clouds will be addressed, namely
how star formation rates in these clouds depends on the local gas density and how giant molecular clouds form and collapse. A final major part of the proposal is dedicated to the thriving field of exoplanets: the detection of planets with direct imaging using one of the leading facility in the world, namely the Gemini telescopes, and the observation of exoplanet atmospheres, using the Hubble Space Telescope and the spanish GTC 10.4-m telescope.

We expect that several of the techniques we develop will have applications outside astronomy, and we will continue to ensure we are connected with the appropriate communities to disseminate them. Primary areas for knowledge exchange are supercomputing, fluid dynamics, atmospheric and solar modelling and statistics.

The science in this proposal most likely to have a broad impact is the work on the atmospheres of extra-solar planets. The understanding developed from this work may well have an impact on our understanding of the Earth's climate, with the potential for wide economic benefits. This was one of the reasons we organised the first "Exoclimes" conference to link scientists working on the Earth and other Solar System planets with those working in exo-planet atmospheres. Further linkage is provided through the three professorial positions in the mathematics department which are jointly funded by the Met Office, whose interests include climate modelling. Similarly the work on the solar dynamo may have climate impacts, but also links to our understanding of the Earth's interior, with an obvious dissemination route via Zhang, as he is editor-in-chief of the journal "Physics of Earth and Planetary Interiors".

Computational fluid dynamics has a wide range of applications in engineering as well as in the entertainment industry for special effects, and the uses of high performance computing are even broader. We will continue to exchange knowledge in these fields via special interest groups within the UK and Europe, as well as through exchange of personnel.

Science is part of the UK's culture, and the academics involved in this proposal have developed a diverse and active outreach programme over the last few years. This programme has the additional aim of encouraging young people into science, which will have long-term benefits for the UK economy. As a result, we have deliberately aimed a significant part of our programme at school children. Over the three years since our "fun, informative and inspiring" International Year of Astronomy Open Evening (2009), we have actively increased our public outreach programme, offering talks, hands-on activities and demonstrations to around 2000 local people, roughly half of them under 18. This is in addition to the more conventional effort of individual members of staff talking to astronomy societies and other interested groups. Over the course of this grant, we propose to expand our visits to secondary schools, reaching the scientists of the future and key in the widening participation agenda.

Finally the post-docs and graduate students working on this programme will gain skills which are highly sought after by employers outside the academic field; our PhD students have moved into scientific publishing and non-academic research, in addition to those who have continued in academia.