Photometry and structure of the young open cluster NGC 7380.

An extensive investigation of NGC 7380 has been made using photographic UBV photometry. The program contains all stars for which V < 16m.35 within a circle of 31' diameter surrounding NGC 7380. A distance of (3.6 + 0.7 max error) kpc and an age of 2.106 years were derived. Extinction of early-type members and projected star density counts indicate that NGC 7380 is surrounded by two dust shells at central radius r = 6'.5 and r = 10:4 with a possible third one at r > 13'. The dust mass of the innermost shell is large ( 50 o) compared to the H n mass (2000 : Schwartz, 1970 - here revised with new distance) and the stellar mass (440 : lower limit). A deficit of faint stars in the central region (r <3') is observed. This may be due to mass-dependent intermption of star formation by H Ir. A connection of the deficit and the dust shells with the association Cep OB 1 is not established. Key words: open cluster - NGC 7380 - dust shells - star density counts