The ubiquity ofjet phenomena in young stellar objects, active galactic nuclei, sym- biotic stars, planetary nebulae and x-ray binaries has driven a broad literature on the astrophysics of collimated mass ejection. One of the fundamental open problems in star formation is the understanding of the physical mechanisms by which mass is ejected from the protostellar system and collimated into jets. Locally jets will regulate the system angular momentum and therefore its evolution during the first few million years. At large scale jets inject momentum into the cloud thus affecting its star formation efficiency and evolution. Many recent advances in the star formation field in both theoretical and observa- tional aspects together with the increasing availability of computational resources, conveyed for a perfect opportunity to organise this workshop which we entitled - Jets 2002: Theory and Observations in YSOs. The workshop main aim was to provide a rich and varied ground for discussion of thejet phenomenon in different astrophysical objects, covering interdisciplinary areas such as steady state winds, time-dependent winds/jets,jet energetics and jet/wind propagation. The workshop took place at the Faculdade de Arquitectura da Universidade do Porto from 3-5 September 2002 and was part of the Joint European National Astronomical Meeting 2002 organized by Sociedade Portuguesa de Astronomia.

The workshop on The Very Large Telescope Interferometer: Challenges for the Future, which was part of JENAM 2002 organised by Sociedade Portuguesa de Astronomia, took place at the Departamentos de Matematica Aplicada e Matemclt- ica Pura da Universidade do Porto (FCUP) from the 5th to the 7th of September 2002. The Very Large Telescope Interferometer (VLTI) is the major interferometric facility in the world, operated by the European Southern Observatory. It is a unique facility as it is available to the community and has a sensitivity that will bring into reach vast classes of objects in the fields of planet searches, star formation and evolution and extragalatic astrophysics. The VLTI was open to the community on a shared risk basis in March 2002. This workshop was therefore an ideal place to obtain a broad view of optical interferometry and its scientific prospects. The workshop started with a presentation of the basics of interferometry the- ory/practice, then of the VLT, Keck and LBT interferometers. The VLTI instru- ments MIDI and AMBER were introduced to its users as well as specific cal- ibration and modelling tools. The bulk of the workshop addressed astrophysics being currently done with interferometers with very high quality reviews in the fields star formation, imaging, pulsating stars, Mira stars, active stellar shells and extragalactic astronomy. The workshop featured some talks presenting fresh VLTI data using the VINCI commissioning instrument.

The workshop on The Very Large Telescope Interferometer: Challenges for the Future, which was part of JENAM 2002 organised by Sociedade Portuguesa de Astronomia, took place at the Departamentos de Matematica Aplicada e Matemclt- ica Pura da Universidade do Porto (FCUP) from the 5th to the 7th of September 2002. The Very Large Telescope Interferometer (VLTI) is the major interferometric facility in the world, operated by the European Southern Observatory. It is a unique facility as it is available to the community and has a sensitivity that will bring into reach vast classes of objects in the fields of planet searches, star formation and evolution and extragalatic astrophysics. The VLTI was open to the community on a shared risk basis in March 2002. This workshop was therefore an ideal place to obtain a broad view of optical interferometry and its scientific prospects. The workshop started with a presentation of the basics of interferometry the- ory/practice, then of the VLT, Keck and LBT interferometers. The VLTI instru- ments MIDI and AMBER were introduced to its users as well as specific cal- ibration and modelling tools. The bulk of the workshop addressed astrophysics being currently done with interferometers with very high quality reviews in the fields star formation, imaging, pulsating stars, Mira stars, active stellar shells and extragalactic astronomy. The workshop featured some talks presenting fresh VLTI data using the VINCI commissioning instrument.

This volume presents the results of the workshop discussions on the jet phenomenon on different astrophysical scales and covers interdisciplinary areas such as steady state winds, time-dependent winds/jets, jet energetics and jet/wind propagation.