A Galactic Eclipse: The Small Magellanic Cloud is Forming Stars in Two, Superimposed Systems
Abstract
The structure and dynamics of the star-forming disk of the Small Magellanic Cloud (SMC) have long confounded us. The SMC is widely used as a prototype for galactic physics at low metallicity, and yet we fundamentally lack an understanding of the structure of its interstellar medium (ISM). In this work, we present a new model for the SMC by comparing the kinematics of young, massive stars with the structure of the ISM traced by high-resolution observations of neutral atomic hydrogen (HI) from the Galactic Australian Square Kilometer Array Pathfinder survey (GASKAP-HI). Specifically, we identify thousands of young, massive stars with precise radial velocity constraints from the Gaia and APOGEE surveys and match these stars to the ISM structures in which they likely formed. By comparing the average dust extinction towards these stars, we find evidence that the SMC is composed of two structures with distinct stellar and gaseous chemical compositions. We construct a simple model that successfully reproduces the observations and shows that the ISM of the SMC is arranged into two, superimposed, star-forming systems with similar gas mass separated by ~5 kpc along the line of sight.
Keywords
Cite
@article{arxiv.2312.07750,
title = {A Galactic Eclipse: The Small Magellanic Cloud is Forming Stars in Two, Superimposed Systems},
author = {Claire E. Murray and Sten Hasselquist and Joshua E. G. Peek and Christina Willecke Lindberg and Andres Almeida and Yumi Choi and Jessica E. M. Craig and Helga Denes and John M. Dickey and Enrico M. Di Teodoro and Christoph Federrath and Isabella A. Gerrard and Steven J. Gibson and Denis Leahy and Min-Young Lee and Callum Lynn and Yik Ki Ma and Antoine Marchal and N. M. McClure-Griffiths and David Nidever and Hiep Nguyen and Nickolas M. Pingel and Elizabeth Tarantino and Lucero Uscanga and Jacco Th. van Loon},
journal= {arXiv preprint arXiv:2312.07750},
year = {2023}
}
Comments
ApJ accepted. 20 pages, 18 figures