THE GALACTIC OPEN CLUSTER NGC-7419 AND ITS 5 RED SUPERGIANTS

UBV CCD photometry has been carried out on the heavily reddened (A(V) = 6.7) Cepheus open cluster NGC 7419. An age of 14 +/- 2 million yr an d a distance of 2.3 kpc have been derived using the isochrones of Maed er. The mass function of the cluster satisfies the Salpeter form N(M) is similar to M(-gamma) with gamma = 2.25. The cluster is dynamically relaxed. Radial velocities of the five red supergiants and the six bri ghtest blue stars (mean almost-equal-to -74 km s-1) confirm their memb ership. However, the radial velocity of the nearby carbon star (MZ Cep ) is a factor of 2 too low for it to be a member. There is at most one blue supergiant member; this is much less than the number of red supe rgiants, in contrast with theoretical predictions. The red supergiants range in type from M2Iab to M7.5I, the coolest (MY Cep)-an OH/IR sour ce-being strongly variable in the visible, but not in the IR. The two supergiants cooler than M2 do not fit the theoretical isochrones.