Date of Award


Document Type

Open Access

Degree Name

Bachelor of Science


Physics and Astronomy

First Advisor

Rebecca Koopmann




galaxies, gas, star formation, environment


Environmental interactions in groups and clusters of galaxies are thought to alter the evolution of member galaxies. The goal of this research was to analyze gas and star formation properties of galaxies in the NGC 5846 group. A sample of group galaxies was observed at CTIO (Cerro Tololo Inter-American Observatory in Chile) and KPNO (Kitt Peak National Observatory) using broadband red (R) and narrowband hydrogen emission line (Hα) filters. The images were reduced and analyzed to extract star formation rates and distributions. Neutral hydrogen data from the Arecibo Legacy Fast ALFA (ALFALFA) survey were used to measure the cold neutral gas content, which provides the raw material for star formation. The amounts and extents of star formation in the sample galaxies are compared as a function of cold gas content, galaxy type, and position in the group and compared to those of galaxies located in other environments. Of the NGC 5846 galaxies sampled using the wide-field MOSAIC camera at KPNO, 32% had Hα emission detected. The star-forming galaxies in the NGC 5846 group show a range of star formation rates, with a number that have lower mean star formation rates and gas content compared to isolated galaxies, but also a few that show enhanced star formation. Truncated star formation similar to that of galaxies in the Virgo Cluster is seen in several NGC 5846 galaxies. These results indicate the possibility of environmental interactions in this intermediate density group environment.