Uncovering the kiloparsec-scale stellar ring of NGC5128

TL;DR

This study provides a detailed near-infrared analysis of the kiloparsec-scale stellar ring in NGC5128, revealing hundreds of point sources and offering insights into its structure and stellar content.

Contribution

It presents the first high-resolution near-infrared imaging of the stellar ring in NGC5128, identifying individual sources and analyzing the structure's shape and stellar population.

Findings

The structure contains hundreds of point-like sources.

Most luminous sources are red supergiants or low-mass star clusters.

The total near-infrared luminosity is approximately M = -21 mag.

Abstract

We reveal the stellar light emerging from the kiloparsec-scale, ring-like structure of the NGC5128 (Centaurus A) galaxy in unprecedented detail. We use arcsecond-scale resolution near infrared images to create a "dust-free" view of the central region of the galaxy, which we then use to quantify the shape of the revealed structure. At the resolution of the data, the structure contains several hundreds of discreet, point-like or slightly elongated sources. Typical extinction corrected surface brightness of the structure is K_S = 16.5 mag/arcsec^2, and we estimate the total near infrared luminosity of the structure to be M = -21 mag. We use diffraction limited (FWHM resolution of ~ 0.1", or 1.6 pc) near infrared data taken with the NACO instrument on VLT to show that the structure decomposes into thousands of separate, mostly point-like sources. According to the tentative photometry, the most luminous sources have M_K = -12 mag, naming them red supergiants or relatively low-mass star clusters. We also discuss the large-scale geometry implied by the reddening signatures of dust in our near infrared images.