CONTOURS OF CONSTANT DENSITY AND Z-HEIGHT FOR CEPHEIDS

We have constructed the contours of constant surface density and Z hei ght for Cepheids within 3 kpc of the sun. We used the GRAFOR software library of Bayakovskii et al. [GRAFOR: a Graphical Extension of Fortra n [in Russian], Nauka, Moscow (1985)], and the Cepheid distances were taken from Berdnikov [Perem. Zvezd. 22, 505 (1987)]. Several enormous complexes in the Carina-Sagittarius arm are sketched out; these lie ap proximately 1 kpc from one another, with the older complex being above the mean Galactic plane, and the younger ones on either side of it an d slightly below the plane. We have basically confirmed the suggestion made by Alfaro et al. [Astrophys, J. 399, 576 (1992)] that the surfac e profile of the Galactic disk is related to the density of young clus ters. Corrugations are observed throughout the Galactic disk even outs ide the spiral arms, while giant stellar complexes are concentrated wi thin the arms-especially the Car-Sgr arm-probably because it comprises part of the Galaxy-spanning regular spiral structure.