Open Clusters in Carina: NGC 3603, Westerlund 2 and Sher 1

ORSATTI, A.M.; VEGA, E.I.; MARTÍNEZ, R.E.

REVISTA MEXICANA DE ASTRONOMíA Y ASTROFíSICA

UNIV NACIONAL AUTONOMA MEXICO

Lugar: México; Año: 2013 vol. 49 p. 285 - 299

0185-1101

Aims. We present polarimetric observations in the UBVRI bands of stars located in the direction of the young open clusters NGC 3603, Westerlund 2 and Sher 1, on the Carina arm and at different distances from the Sun. Our main objectives are to study the characteristics of the dust lying between the Sun and the clusters and to analyze polarimetric evidences on the existence (or not) of abnormal reddening in NGC 3603 and Westerlund 2, two open clusters in close relationship with H II regions. Also, to identify starswith signatures of intrinsic polarization, to compare with the number found in other clusters associated to H II regions (e.g. in NGC 6611)Methods. The observations were carried out using the five-channel photopolarimeter of the Torino Astronomical Observatory attachedto the 2.15m telescope at the Complejo Astron´omico El Leoncito (CASLEO; Argentina).Results. A 40% of observed members inWesterlund 2 presents indications of intrinsic polarization, similar to the number found in the core of NGC 6611 and also in the polarimetric study of IC 2944, another open cluster in close relation with an H II region (RWC62); but in NGC 3603, the percentage is very small. Even with a reduced number of observations, polarimetry is in favor of the existence of abnormal reddening in NGC 3603, while in Westerlund 2 there are only indications, and more observations are needed.