The search for
planets hosting life is one of the major goals of the astronomy of this
century. To this purpose, the European
Space Agency (ESA) and the NASA have began long term reasearch programs. The
first step is the discovery of exosolar planetary systems, and the full
understanding of their formation mechanisms. However, detection of exosolar
planets requires very sophisticated techniques. It was only in
1995 that a group of swiss astronomers, leadered by
Michel Mayor and Didier Queloz announced the discovery of the first planet
orbiting around a star different from the Sun. Since then, about one hundred
exosolar planets have been discovered. Their often surprising charactaristics
require a drastic revision of current theories of planet formation based on the
knoweledge of the Solar System alone. Theorists are then eager for new
discoveries in order to improve their models, and observers are comepeing to
provide adequate data, including size, mass, and distance from the central star
for a larger and larger number of planets.
Up to now, Italian astronomy was out of this important research field. However, now situation is changing. Thanks to Telescopio Nazionale Galileo, of the National Istitute for Astrophysics (INAF), operating since a few years on the island of La Palma, and of its high resolution spectrograph SARG (built by the Astronomical Observatories of Padua, Catania, Palermo, and Trieste), a group of astronomers of Padua and Catania, leadered by Raffaele Gratton (Padua Observatory, INAF), has found a planet candidate orbiting the star HD219542B. This the first of a hopefully long series for Italy.
Silvano Desidera, a young astronomer from Padua, among the protagonists of the discovery, say:
“ The planet should have the mass of Saturn, but at a distance from the star intermediate between those of Mercury and Venus from the Sun. Some caution is anyway required because this would be one of the smallest planets found so far. Further observations are in progress”. Francesco Marzari, a theoretician from Padua expert in planet formation mechanisms: “ The discovery is of particular relevence because it is a relatively small planet with respect to those observed insofar. It might be similar to the external planets of the solar system, that are made of a solid nucleus and a gaseous envelope. At the same mass, its radius should however be larger than that of Saturn, since its closeness to the star induce high temperature at the surface”.
Investigations by
the Gratton group are continuining: since about two years about one hundred
stars are observed in order to discover orbiting planets. New exciting results
are expected in the few years.
We are using the AUSTRAL software provided by M. Endl (Mc Donald Obsevatory, Austin, TX 78712, USA)
Further contact:
email: gratton@pd.astro.it,
desidera@pd.astro.it, claudi@pd.astro.it
phone:
049/8293442
TEAM:
Raffaele Gratton, Riccardo Claudi, Silvano Desidera, Sara Lucatello INAF Astronomica Observatory of Padova
Giovanni Bonanno, Rosario Cosentino, Salvo Scuderi INAF Astronomica Observatory of Catania
Francesco Marzari, Mauro Barbieri Padova University Dep. of physics