Lifting the Veil of Dust from NGC 0959: The Importance of a Pixel-Based 2D Extinction Correction

TL;DR

This study demonstrates that applying pixel-based dust extinction correction to NGC 0959 significantly enhances the ability to analyze its stellar populations and structures, revealing features like a hidden bar.

Contribution

It introduces and applies a pixel-based 2D dust extinction correction method to galaxy imaging data, improving the analysis of stellar populations and galaxy structures.

Findings

Pixel-based extinction correction reveals spatial stellar population variations.

Corrected pixel color diagrams distinguish different stellar populations.

A previously unrecognized galactic bar is identified after correction.

Abstract

We present the results of a study of the late-type spiral galaxy NGC 0959, before and after application of the pixel-based dust extinction correction described in Tamura et al. 2009 (Paper I). Galaxy Evolution Explorer (GALEX) far-UV (FUV) and near-UV (NUV), ground-based Vatican Advanced Technology Telescope (VATT) UBVR, and Spitzer/Infrared Array Camera (IRAC) 3.6, 4.5, 5.8, and 8.0 micron images are studied through pixel Color-Magnitude Diagrams (pCMDs) and pixel Color-Color Diagrams (pCCDs). We define groups of pixels based on their distribution in a pCCD of (B - 3.6 micron) versus (FUV - U) colors after extinction correction. In the same pCCD, we trace their locations before the extinction correction was applied. This shows that selecting pixel groups is not meaningful when using colors uncorrected for dust. We also trace the distribution of the pixel groups on a pixel coordinate map of the galaxy. We find that the pixel-based (two-dimensional) extinction correction is crucial to reveal the spatial variations in the dominant stellar population, averaged over each resolution element. Different types and mixtures of stellar populations, and galaxy structures such as a previously unrecognized bar, become readily discernible in the extinction-corrected pCCD and as coherent spatial structures in the pixel coordinate map.