Imaging of I Zw 18 by JWST. I. Detecting Dusty Stellar Populations
Journal article, 2024
We present a JWST imaging survey of I Zw 18, the archetypal extremely metal-poor, star-forming (SF), blue compact dwarf galaxy. With an oxygen abundance of only similar to 3% Z circle dot, it is among the lowest-metallicity systems known in the local Universe, and is, therefore, an excellent accessible analog for the galactic building blocks which existed at early epochs of ionization and star formation. These JWST data provide a comprehensive infrared (IR) view of I Zw 18 with eight filters utilizing both Near Infrared Camera (F115W, F200W, F356W, and F444W) and Mid-Infrared Instrument (F770W, F1000W, F1500W, and F1800W) photometry, which we have used to identify key stellar populations that are bright in the near- and mid-IR. These data allow for a better understanding of the origins of dust and dust-production mechanisms in metal-poor environments by characterizing the population of massive, evolved stars in the red supergiant (RSG) and asymptotic giant branch (AGB) phases. In addition, it enables the identification of the brightest dust-enshrouded young stellar objects (YSOs), which provide insight into the formation of massive stars at extremely low metallicities typical of the very early Universe. This paper provides an overview of the observational strategy and data processing, and presents first science results, including identifications of dusty AGB, RSG, and bright YSO candidates. These first results assess the scientific quality of JWST data and provide a guide for obtaining and interpreting future observations of the dusty and evolved stars inhabiting compact dwarf SF galaxies in the local Universe.
Author
Alec S. Hirschauer
Space Telescope Science Institute (STScI)
Nicolas Crouzet
Leiden University
Nolan Habel
California Institute of Technology (Caltech)
Laura Lenkic
California Institute of Technology (Caltech)
NASA Ames Res Ctr, Stratospher Observ Infrared Astron, Mail Stop 204-14
Conor Nally
University of Edinburgh
Olivia C. Jones
UK Astron Technol Ctr
Giacomo Bortolini
Stockholm University
Martha L. Boyer
Space Telescope Science Institute (STScI)
Kay Justtanont
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Margaret Meixner
California Institute of Technology (Caltech)
Goran Ostlin
Stockholm University
Gillian S. Wright
UK Astron Technol Ctr
Ruyman Azzollini
University College London (UCL)
Joris A. D. L. Blommaert
Vrije Universiteit Brussel (VUB)
Bernhard Brandl
Leiden University
Leen Decin
Katholieke Univ Leuven
Omnarayani Nayak
NASA Goddard Space Flight Center
Space Telescope Science Institute (STScI)
Pierre Royer
Katholieke Univ Leuven
B. A. Sargent
Space Telescope Science Institute (STScI)
Johns Hopkins University
Paul van der Werf
Leiden University
Astronomical Journal
0004-6256 (ISSN) 1538-3881 (eISSN)
Vol. 168 1 23Subject Categories
Astronomy, Astrophysics and Cosmology
Computer Vision and Robotics (Autonomous Systems)
DOI
10.3847/1538-3881/ad4967