Among the main questions being posed throughout our existence are those that concern our origin and roots such as “where do we come from?” and “how did the Sun, stars and planets form?” Progress in answering them has been remarkable, but many important questions regarding star formation still exist.
More than 100 years ago, Sir James Jeans considered the formation of the Solar System and proposed that it began as a huge gaseous cloud containing only atoms and molecules. He showed that if such a cloud exceeded a certain mass, the mutual gravitational attraction between these particles would be sufficient to cause the cloud to shrink to ever smaller sizes and higher densities. As the contracting gas can heat up, the net result of this "gravitational contraction" is an enormously hot, dense, object where the conditions are extreme enough for nuclear fusion to begin. A star is born. Such clouds had in fact been discovered already back in the 18th century, when Sir William Herschel found well-defined dark patches on the sky. His first reaction was one of shock, "My God, here truly is a hole in the sky!", but we now know that in these places there are so many dust particles that they can block the light from the background stars just as fog blocks our view on a misty day. These dark clouds turn out to be massive enough to provide the material to build one or more stars. The cradles of stars were found.
An additional finding is that many stars are not alone, but are often clustered in groups of dozens to even hundreds of stars. The STARRY project focussed on the clustering properties of young stars and is based on research in the nineties which reported that young massive stars were mostly found in clusters, while lower mass young stars were not. We address this issue using the results of an on-going European Space Agency’s space telescope mission, Gaia.
STARRY consists of two related projects, that were each carried out by an Early Stage Researcher. The first project's objectives were studying the properties of the known young stars from a statistical point of view using the new information thanks to Gaia, and aimed at discovering more such stars in the huge dataset. Its results fed into the second project, whose objective it was to study clusters around these young massive stars.
The project was very timely, as it started when the results of the Gaia satellite were released. Gaia measured parallaxes for more than a billion stars, a 10,000 fold increase to what was available previously. These data allow the distances to objects and their properties such as mass and brightness to be determined.
