Young Star Clusters and Associations
(Barentsen, Drew, Lucas, Riaz, Thompson, Wright)
The great majority of stars are born in star clusters. At the same time a high proportion of clusters do not survive beyond the embedded phase, in which the enshrouding dust acts to significantly dim the appearance of clusters at visible wavelengths. The study of young star clusters is therefore a natural topic to pursue at red, near-infrared and longer wavelengths - and it is important precisely because they are the sites within which stars were recently formed and may continue to form (through a range of dynamic processes).
At Hertfordshire we occupy the leading role in a range of Galactic Plane photometric surveys, and have involvement with the the Gaia-ESO survey - a VLT/FLAMES spectroscopy survey that subsumes a major programme focusing on the analysis of star clusters, ahead of the precise distance measurements that the Gaia mission will provide. Our photometric surveys provide the wide-field data critical to unbiased searches and analyses of star clusters aimed at understanding how they evolve and nurture continuing star formation. We are conducting searches for clusters via the UKIDSS/GPS survey, and use IPHAS and VPHAS+, along with data from other wavelengths, for whole-cluster studies of e.g. Cyg OB2 and IC1396 (figure below).
IC 1396, a young star cluster still experiencing star formation, located in the northern Galactic Plane (Barentsen et al 2011, MNRAS, 415, 103). H-alpha narrowband and Sloan r, i data from the IPHAS survey are merged in this image spanning a sky region of roughly 3 x 3 square degrees.
We are studying the evolution of star formation across molecular cloud complexes as traced by clusters and other indicators such as methanol masers. With VVV, IPHAS, VPHAS, UKIDSS/GPS and Spitzer/GLIMPSE360 we are also tracing the more dispersed pre-main sequence population via variability, Halpha emission and infrared excess.