Scientific Projects

• Star formation in starburst: a deep ACIS-I observation of Westerlund 1

At the distance from the Sun of 13000 light years, Westerlund 1 is the closest starburst cluster to us. While the typical star forming regions in our Galaxy form hundreds to a few thousand stars, starburst clusters form tens of thousand to million of stars. They thus represent one of the most extreme environments in terms of stellar density and local radiation field (mainly UV radiation). Despite they are rare now in our Galaxy, starburst clusters were common in the early Universe and when the Milky Way was a young galaxy forming stars at a very high rate. The study of Westerlund 1 will thus shed some light on the formation of stars and planets in the early past of our Galaxy.


Optical image of Westerlund 1

Simulated Chandra/ACIS-I  observation of Westerlund 1, with marked the position of known massive stars


I am the P.I. of a project, mainly based on a Chandra/ACIS-I observation of 1Msec, aimed at studying several topics of star formation and evolution in starburst:

  • the study of the evolution of the protoplanetary disks in starburst clusters to verify whether they can be quickly destroyed by the surrounding environment before they can form planets;
  • if planetary formation is possible in starburst, to verify whether planets can accrete enough mass to become giants planets and whether the chemical properties of planets is affected by the starburst environment;
  • to verify whether the mass spectrum of the stars born in starburst is the same of that of the Galaxy today, or whether starburst clusters form preferentially massive or low-mass stars, down to the brown dwarf regime;
  • to study the formation mechanism of the starburst clusters and to understand if it is different than that forming normal clusters, and also to understand whether starburst clusters are doomed to disperse in a few million years as most of the low-mass clusters or whether their intense gravitational field bound these clusters for billion of years as the globular clusters;
  • to verify whether Intermediate Massive Black Holes, responsible for most of the gravitational waves detected by LIGO and VIRGO, typically form in starburst clusters by coalescence, as suggested by theoretical works;
  • to analyze the X-ray emission from the large numbers of massive stars of the starburst clusters. These clusters typically host some of the most massive stars in the Universe and also stars covering a wide range of transient evolutionary phases, where X-rays can be produced by different mechanisms;
  • to study the transient source CXOU J164710.2-455216, which is a particular type of neutron star called magnetar.

The team of the project counts to date 23 astronomers: 8 astronomers from the INAF institutes in Palermo, Rome and Padua, 2 astronomers from the University of Palermo, and 13 astronomers from UK, USA, Chile, Argentina, and Portugal.