Objectives

The principal objectives of this project are:

  1.  To study the structure and dynamics of the solar interior.
  2.  To extend this study to other stars.
  3.  To search for extrasolar planets using photometric methods.

To reach our first objective, we use the only known technique: Global Helioseismology (to probe the deep interior of the Sun) and Local Helioseismology (to undertake a more detailed study, but limited to the outer 10% of the Sun). Through the detection and investigation of the solar oscillation mode spectrum it is possible to accurately infer information about its interior structure and dynamics, that is, the determination of the most important physical profiles from the center to the surface of the Sun. This project covers the various necessary aspects to attain the aforementioned objectives: a) Instrumental, which has been previously a strong component of our work and we continue to be involved in new space-based and ground-based projects; b) Observational, we work with continuous uninterrupted data from various global helioseismological networks (BiSON and GONG), as well as data from GOLF and VIRGO onboard SOHO; c) Techniques of reduction, analysis and interpretation of data; d) Theoretical developments of inversion techniques of data and development of solar stellar and structure models. Results have shown that we can understand the details of the Sun with a precision of the order of 0.1%, and it is this that has allowed us to contribute effectively towards the now well-known problem of solar neutrinos.

It does not come as a surprise that we aim to understand other stars in the same way as we do the Sun through Asteroseismology or Stellar Seismology. Of course measuring stellar oscillation mode spectra is very difficult and depends on the type of star under study. Obtaining information about the internal structure, evolution and dynamics of stars on the main sequence (MS) and (as is in our present project) from other more evolved stars (hot subdwarfs), requires instrumental techniques and observation strategies that  are now possible thanks to several satellite missions as CoRoT and Keppler.

The strategy of using planetary transits to discover new planets around other stars consists of the photometric detection of a dimming of light (in various filters too) of the star when one of its planets is passing in front of it (from the observer's point of view). Currently this method is the only form that has allowed the detection of planets similar to the Earth, not only because of the sensitivity that new technology has allowed us to reach, but also because this method allows one to investigate details of the planets (e.g. Planetary atmospheres). This technique is similar to the one that is used for helio- and astero-seismology and so it is clear that it is a logical extention from that. However, it is also important to develop new algorithms for the unequivocal detection of planets and to be able to distinguish them from false alarms.

The CoRoT satellite, which operates since 2007, entered during 2010 into the second half of its operational life-time, and work of the group related to exoplanets and to asteroseismology is centred on its exploitation.

During 2010, we have also seen the massive arrival of data from the Kepler space mission. Although designed by NASA to discover Earth-like planets, it is the European Consortium KASC (Kepler Asteroseismic Science Consortium) which is taking the exclusive responsibility to exploit the asteroseismologic content of its data. The continuous observations of thousands of stars for more than four years will result in data of a precision that points towards a major revolution in the domain of Stellar Structure and Evolution.