Star Formation, Structure and Evolution of Group Galaxies: The Environmental Connection
Session 61 -- Properties and Evolution of Clusters of Galaxies
Display presentation, Thursday, 2, 1994, 9:20-6:30

## [61.14] Star Formation, Structure and Evolution of Group Galaxies: The Environmental Connection

P.M. Marcum, J.S. Gallagher (U. Wisconsin), P.N. Appleton (Iowa State U.)

Despite the numerous theories developed over the last few decades, the fundamental question of why some galaxies are dominated by a spheroidal component while others exist largely as rotationally-supported disk systems remains unresolved. Is the difference a consequence of initial conditions, galaxy interactions, or internal evolution ? The complete answer is undoubtedly a complicated mixture of all three mechanisms. In this poster, we access the importance of environmentally-related processes. Broadband R and near infrared images to are used to determine the variation in bulge-to-disk ratios for galaxies which are members of groups displaying a range in galaxy number density and richness. These data thus allow us to determine if correlations exist between the local present-day environments and basic galactic structures. Using H$\alpha$ imaging, the ongoing star forming properties of the group members are compared. Finally, we take advantage of the 1-degree field of view of the H$\alpha$ images to investigate the line-emitting dwarf galaxy population within the different group environments to see if the nature of the group members is correlated with the presence or absence of dwarfs.