The Abundance Gradient of NGC 2403 and Comparisons to M33

by Stanley Paul Sagan

Under the supervision of Professor Evan D. Skillman

ABSTRACT

High Signal-to-Noise observations are presentd of 11 H II regions in the Scd spiral galaxy NGC 2403. Abundances are determined by both an empirical method and by a direct method using 8 detections of the temperature sensitive [OIII] 4363 line.
Abundance gradients for oxygen and nitrogen are found to be -0.094±0.004 dex/kpc and -0.104 ±0.004 dec/kpc respectively. Mass distribution data for the disk are collected from literature, and the "simple, closed box" chemical evolution model is tested. It is found that oxygen is underabundant and nitrogen fits well. Comparisons are made to M33, another Scd galaxy, and evolutionary characteristics are shown to be similar. Radial oxygen abundance gradients are found to be equal.