Star Formation Rate Distribution in the Galaxy NGC 1232

TL;DR

This study provides a detailed catalog of H ii regions in NGC 1232, analyzes their luminosity and size distributions, and investigates the impact of a recent collision on star formation activity.

Contribution

It presents the most complete H ii region catalog for NGC 1232, analyzes its luminosity and size distributions, and links star formation patterns to a recent galactic collision.

Findings

Cataloged 976 H ii regions, doubling previous counts.

Found a shallower luminosity function slope than typical for Sc galaxies.

Observed star formation quenching near intense X-ray emission regions.

Abstract

NGC 1232 is a face-on spiral galaxy and a great laboratory for the study of star-formation due to its proximity. We obtained high spatial resolution H{\alpha} images of this galaxy, with adaptive optics, using the SAM instrument at the SOAR telescope, and used these images to study its H ii regions. These observations allowed us to produce the most complete H ii region catalog for it to date, with a total of 976 sources. This doubles the number of H ii regions previously found for this object. We used these data to construct the H ii luminosity function, and obtained a power-law index lower than the typical values found for Sc galaxies. This shallower slope is related to the presence of a significant number of high-luminosity H ii regions (logL>39 dex). We also constructed the size distribution function, verifying that, as for most galaxies, NGC 1232 follows an exponential law. We also used the H{\alpha} luminosity to calculate the star formation rate. An extremely interesting fact about this galaxy is that X-ray diffuse observations suggest that NGC 1232 recently suffered a collision with a dwarf galaxy. We found an absence of star formation around the region where the X-ray emission is more intense, which we interpret as a star formation quenching due to the collision. Along with that, we found an excess of star-forming regions in the northeast part of the galaxy, where the X-ray emission is less intense.