UBVI and H alpha photometry is presented for 17319 stars in vicinity of the young double cluster h and chi Persei. Our photometry extends over a 37' x 1 degrees field centered on the association. We construct reddening contours within the imaged field. We find that the two clusters share a common distance modulus of 11.75 +/- 0.05 and ages of log age(yr) = 7.1 +/- 0.1. From the V-H alpha color, a measure of the H alpha emission strength, we conduct a survey for emission line objects within the association. We detect a sample of 33 Be stars, eight of which are new detections. We present a scenario of evolutionary enhancement of the Be phenomenon to account for the peak in Be fraction toward the top of the main sequence in the population of h and chi Persei and similar young clusters. References: 42
展开▼
