Talk

Does the environment matter? Investigating the spin rates of low mass stars in the young Cygnus OB2 association

Julia M T Roquette, University of Exeter

In recent decades, observational studies targeting clusters and associations at a variety of ages helped to constrain our understanding of the rotational evolution of low mass stars during the early pre-main sequence. During the first 10 Myrs, a significant fraction of the low mass stars still holds a circumstellar disk. While it is generally accepted that the star-disk interaction dominates their rotational evolution, very few studies take into consideration how the cluster environmental conditions can impact the disk-evolution and therefore change the early rotational evolution of the lower mass stars. Does the environment matter? We tackled this question by investigating the rotational properties of low mass stars in the young massive association Cygnus OB2 (3-7 Myrs, 1.45 kpc). Cygnus OB2 harbors a very rich high mass population of about 160 OB stars, which are responsible for producing intense ultraviolet fields that can make some regions within the association hostile for the disk-evolution. We present partial results of two observational campaigns dedicated to investigating the impact of those OB stars on the rotational properties of the coeval low mass star in the association. We used near-infrared light curves obtained with WFCAM/UKIRT and WIRCAM/CFHT to derive spin rates for approximately a thousand association members. We present a comparison between the results supporting a disk-rotation connection for sub-groups of stars in regions of the association with high and low UV incidence.