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A Gaia and Herschel Study of the Density Distribution and Evolution of Young Massive Star Clusters

Periodic Reporting for period 3 - StarFormMapper (A Gaia and Herschel Study of the Density Distribution and Evolution of Young Massive Star Clusters)

Reporting period: 2018-09-01 to 2020-08-31

The key aim of this proposal is to combine data from two of ESA's major space missions, Gaia and Herschel, together with ground based facilities, to constrain the mechanisms that underlie massive star and star cluster formation. Collectively, these facilities represent a considerable fraction of the total investment by Europe in astronomy. Taken separately, however, these missions give an incomplete picture but their combination will cover all stages from the formation of molecular cores, through the formation of stars, to the dispersal of the gas in young clusters. We will require new techniques in order to extract the full scientific value from this combination. We will develop new automated statistical techniques and common user tools that will provide a community wide benefit. Our scientific results will underpin the study of how all galaxies evolve.

We achieved most of the goals of this project on completion. The most notable items related to work packages 1-4. The statistical tools developed for the first two work packages, S2D2 and INDICATE, were clearly demonstrated to have great promise for future studies of local clustering properties in very inhomogeneous distributions such as found in Gaia point source data. In addition, both extensions to existing, and new, techniques were used to derive source catalogues from Herschel maps, and different techniques found to give similar results. When combined with the Gaia data in NGC2264 these showed that the youngest sources were the most spatially compact and tightly clustered. The third work package produced a suite of state of the art hydrodynamical models of young massive star formation regions. These have all been made public, as have the tools developed for the first two work packages, for the wider use of the community.
Finally we were able to demonstrate that these tools could be combined into an online adjunct to the existing archives in the fourth work package. This provides a firm basis for future such work.
The work for SFM breaks into 3 broad areas - developing statistical methods for looking for groupings of stars (and assigning a significance to how many neighbours they have), and the gas cores out of which they form; developing simulations to help address the physical mechanisms that underpin what we see in the real data; developing a software environment that makes all of this transparent to the end-user.

More specifically, new algorithms designed to analyse local clustering strength (INDICATE - broadly tests whether stars have more neighbours than expected from a uniform distribution), test for the presence of significant sub-groups (S2D2 - especially looking for small sub-groups of stars which may be a good guide to how they formed in the first place), and apply observational "selection functions" to the simulations which have been created, and all of these made public. A large suite of both N-body and full hydrodynamical models have been developed and also made public. In parallel with these scientific activities Quasar SR have created a complete infrastructure capable of acting as an interface between the user and the ESA archives, incorporating our algorithms along the way. The software to reproduce this is available both online as an active service at both Cardiff and Quasar, and as a download that can be installed on the end-user’s own computer.

Catalogues of stellar sub-groupings are already available for four clusters, and more are being added. A core catalogue has been created for the NGC 2264 region based on HOBYS Herschel data. Analysis of the stellar content of the same region has included the kinematical data for the first time, providing firm evidence for dynamical evolution.

Our work has continued to be published in the refereed literature, with seven papers already published, one more resubmitted after generally supportive referees comments, and a further three in the late stages of preparation. In addition, the final project conference attracted over 80 participants from around the world, and gave them the chance to see both the science being carried out by the project as well as the Quasar software environment in action in a well attended “hands-on” session.

Lastly, we feel we have reached a significant public audience for our work, and would like to highlight in particular the work relating to holograms by both Leeds and Quasar, as well as Quasar’s development for SFM science of their virtual reality system.
We have created new statistical routines that potentially have wider application to point datasets beyond those in astronomy. The method of embedding these tools into server side Docker containers at Quasar SR also has great potential which they plan to exploit in the future. The simulations produced for the project are now essentially complete, and present a suite of which any one would be state of the art but where care is taken to ensure a consistency between the various modelling techniques (eg MHD, N-body+gas, N-body stellar only) that is novel. The project has engaged widely with the broader public, and has preceived press coverage for its outreach developments. The project has also used its platforms to demonstrate that scientific research can work alongside an SME in an effective manner.