Young Star Clusters
The aim of this program is to derive (i) deep and accurate UBVRcIc photometry and (ii) high resolution spectra of cluster members for a well chosen sample of galactic young open clusters. About 15 high resolution spectra are being obtained over a period of 10 years for each cluster member in order to investigate (a) the internal kinematics, (b) the energetics and the parameters of the binary, and (c) the cluster Galactic motion.
Our selection of young open clusters (YOCs) spans a range in total mass, number of member stars, age and total energy. jewelboxcenter In this way we expect to track the evolutionary steps of mass and binary stars segregation, energy equipartition and relaxation. The targets have been chosen among those with already published high quality astrometry. The multicolor CCD photometric allows to derive distance, reddening, age and main sequence morphology. The internal kinematics of YOCs are particularly challenging, as the small velocity dispersion in such stellar groups (few km/sec) imposes an extremely high accuracy on the derived RVs. Our high resolution spectroscopy is obtained with an Echelle spectrograph mounted at the 1.82m telescope operated by INAF OAPd on top of Mt. Ekar in Asiago. Matched with cross-correlation techniques, it provides RVs for early-type stars with single measure precision around 0.5 km/sec. The high dispersion spectra are also useful to derive the projected rotational velocities, the chemical composition and the evolutionary status of the member stars as well as to study the interstellar medium inside and towards these stellar aggregates. The ambitious final goals are to get observationally proved grand-relations governing the dynamical evolution of YOCs which can be compared with the predictions of N-body simulations, and to provide a reliable input for numerical experiments and theoretical models. This is a long term project. The effectiveness and originality of this program depend also on interpreting a statistical relevant sample of data. Up till now data acquisition and/or spectra reduction has been completed for six YOCs and one trapezium system. Observations are still being done for a dozen of other young stellar groups.
People: L. Tomasella, U. Munari
Collaboration: A. Henden (USNO), G. Carraro, R. Barbon (Padova Univ.), C. Boeche (Postdam)
Publications: Munari & Tomasella (1999) A&A 343,806; Boeche et al. (2004) A&A 415,145; Carraro & Munari (2004) MNRAS 347,625