An HST/NICMOS view of the prototypical giant HII region NGC604 in M33

TL;DR

This study provides high-resolution near-infrared imaging of NGC 604 in M33, revealing new stellar sources, structures, and star-forming regions, and correlating NIR features with radio emissions to understand its stellar content.

Contribution

First high-resolution NIR imaging of NGC 604 with HST NICMOS, uncovering new sources, structures, and star-forming regions, enhancing understanding of its stellar complexity.

Findings

Identification of new NIR point sources and clusters.

Correlation between radio continuum and nebular emission.

Detection of candidate red supergiant stars.

Abstract

We present the first high-spatial resolution near-infrared (NIR) imaging of NGC 604, obtained with the NICMOS camera aboard the Hubble Space Telescope (HST). These NICMOS broadband images reveal new NIR point sources, clusters, and diffuse structures. We found an excellent spatial correlation between the 8.4 GHz radio continuum and the 2.2mu-m nebular emission. Moreover, massive young stellar object candidates appear aligned with these radio peaks, reinforcing the idea that those areas are star-forming regions. Three different scaled OB associations are recognized in the NICMOS images. The brightest NIR sources in our images have properties that suggest that they are red supergiant stars, of which one of them was previously known. This preliminary analysis of the NICMOS images shows the complexity of the stellar content of the NGC 604 nebula.