Extinction Distributions in Nearby Star-resolved Galaxies. II. M33

TL;DR

This paper presents a high-resolution extinction map of the galaxy M33, revealing detailed dust distribution and its correlation with interstellar medium components, aiding future stellar and dust studies.

Contribution

It constructs the first detailed, high-resolution extinction map of M33 using multiband photometry of resolved RGB stars, linking dust distribution with gas components.

Findings

Extinction map resolution of approximately 6 arcseconds (~24.4 pc).

Strong spatial correlation between dust and hydrogen gas distributions.

Maximum V-band extinction of 2.5 mag with an average of 1.05 mag.

Abstract

Extinction maps are essential for tracing interstellar dust and enabling accurate stellar population studies in galaxies. Here, a high-resolution extinction distribution of nearby galaxy M33 is constructed by fitting multiband color indexes of the individually resolved red giant branch (RGB) stars from the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) survey. Achieving an angular resolution of approximately 6$^{\prime\prime}$ ($\sim$ 24.4 pc), the extinction map reveals the intricate and heterogeneous distribution of dust throughout the entire disk of M33, with distinct delineation of spiral arms, inter-arm regions, and compact dust clouds. In addition, it exhibits strong spatial correspondence with the distributions of total hydrogen, H I, and CO, underscoring the reliability of the extinction map for tracing both diffuse and dense components of the interstellar medium. The derived $V$-band extinction reaches up to 2.5 mag per pixel, with a mean value of about 1.05 mag. Beyond providing new insights into the dust structure of M33, the extinction map offers a robust foundation for accurate extinction corrections and will support future studies, including upcoming observations with the Chinese Space Station Telescope.