Moreover, Allington-Smith et al. 1993 showed that the BO effect is not present in groups of galaxies, and Tomita et al. 1996 argue that it is not even enhanced at the interface regions between subclusters. Evidently, environment plays a complex but integral role in the BO effect. The ability of optical spectroscopy and imaging to probe these issues has been limited. At the high redshifts of the BO clusters, the Ha line lands in a region of the spectrum near 1 micron where sensitive detectors are only now being developed.
Optical images are biased to emission from hot, young stars and are beset by extinction effects.
To study the nature of the star-formation in BO clusters, we must turn to infrared diagnostics. We request five nights to complete our imaging goals. Since the IR images reveal the distribution of the dominant long-lived stellar population in these galaxies, we can be confident that gravitational interactions are at least partly responsible for the activity in the BO blue galaxies. Using similar diagnostics, Stanford et al. While the quality of the data we collected in September 1994 was good, we were able to improve it significantly by increasing our exposure times in March and November.