Studies of Binary Star Cluster Candidates in the Bar of the LMC. I: SL 353 & SL 349

We present a detailed study of the cluster pair SL 353 & SL 349. This candidate binary cluster is located at the northwestern rim of the LMC bar. Based on photometric data we find that both clusters are coeval with an age of 550 +/- 100 Myr. We use the Ca II triplet in the spectra of individual red giants to derive radial velocities. Both components of the binary cluster candidate show very similar mean velocities (approx. 274 +/- 10 km/sec for SL 349 and approx. 279 +/- 4 km/sec for SL 353) while the field stars show lower velocities (approx. 240 +/- 19 km/sec). These findings suggest a common origin of the two clusters from the same GMC. In this sense the cluster pair may constitute a true binary cluster. We furthermore investigate the stellar densities in and around the star clusters and compare them with isopleths created from artificial, interacting as well as non-interacting star clusters. Gravitational interaction leads to a distortion which can also be found in the observed pair.