A STUDY OF CARINA OB2 ASSOCIATION .2. ANALYSIS AND DISCUSSION OF THE DATA

UBV photometric data and accurate MK spectral types of stars in the region of Carina OB2 association, presented in Paper I, are used to show that Carina OB2 is a genuine stellar association located at a distance of 3.1 kpc from the Sun, and with an age of about 4 x 10(6) yr, in accordance with the bluest star on the main sequence. From the complete sample, a total of 91 O and B stars were retained as members of Carina OB2, while 66 stars were considered probable members. Among the members, there are two early-type supergiant stars, three O-type stars, and 12 giants or subgiant B-type stars. For 37 stars in the field of the association we obtained between 3 and 10 spectrograms per star, and with these data we were able to derive preliminary orbital elements for three spectroscopic binaries and probable periods for two other stars. The ratio of average projected rotational velocity of the cluster members to that of held stars is 0.87 +/- 0.05. The average radial velocity for the group is -23 +/- 2(p.e.) km s(-1). We call attention to several peculiar stars, early-type SB1, and SB2 systems of potential astrophysical interest. Finally, we propose a global picture of the region where Carina OB2 is located and a preliminary analysis of the possible relation between the association and the other clusters present in this wonderful region of the southern sky.