NOEMA Observations of the Center of M33: A Parsec-scale Molecular Filament and an Ordered Gas-Star-Formation Sequence
Abstract
We present NOEMA CO(1-0) observations of the inner ∼500 pc of M33 at a resolution of 0.91''×0.37'' (3.7×1.5 pc), resolving the compact molecular gas structures and revealing their relation to recent massive star formation. The most prominent structure is a southeastern molecular filament (SE filament) that extends 76 pc along its principal axis, is 23 pc wide, and contains three CO-bright knots. Across eight independent transverse cuts, the adjacent Hα ridge is displaced preferentially to one side of the principal CO ridge by a median 10.0+0.9−1.4 pc. Young OB candidates are more closely associated with Hα than with compact CO. The filament shows little velocity change along its length but a resolved gradient across its minor axis. Its elongated morphology, transverse kinematics, and ordered CO-Hα distribution are consistent with locally asymmetric molecular-gas compression and subsequent massive star formation. Across the wider field, 23 well-measured compact clumps have a median radius of 2.67 pc and a median velocity dispersion of 2.15 km s−1. Their linewidth and apparent virial-parameter distributions show no clear difference between the SE filament and the rest of the field. Although the local spiral potential and pattern speed remain unconstrained, the observations provide a resolved view of a compression-compatible molecular-to-ionized-gas sequence in the center of M33.
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BibTeX
@misc{li2026noema,
title = {{NOEMA Observations of the Center of M33: A Parsec-scale Molecular Filament and an Ordered Gas-Star-Formation Sequence}},
author = {Zongnan Li and Zhiyuan Li and Gan Luo and Sheng-Yuan Liu and Sihan Jiao and Fanyi Meng and Zhiyuan Ren and Daisuke Iono and Jiachang Zhang and Di Li and Chao-Wei Tsai and Jongsoo Kim},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.35278},
eprint = {2610.35278},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.35278},
}
RIS
TY - UNPB
TI - NOEMA Observations of the Center of M33: A Parsec-scale Molecular Filament and an Ordered Gas-Star-Formation Sequence
AU - Zongnan Li
AU - Zhiyuan Li
AU - Gan Luo
AU - Sheng-Yuan Liu
AU - Sihan Jiao
AU - Fanyi Meng
AU - Zhiyuan Ren
AU - Daisuke Iono
AU - Jiachang Zhang
AU - Di Li
AU - Chao-Wei Tsai
AU - Jongsoo Kim
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.35278
UR - https://arxiv.org/abs/2610.35278
AB - We present NOEMA CO(1-0) observations of the inner ∼500 pc of M33 at a resolution of 0.91''×0.37'' (3.7×1.5 pc), resolving the compact molecular gas structures and revealing their relation to recent massive star formation. The most prominent structure is a southeastern molecular filament (SE filament) that extends 76 pc along its principal axis, is 23 pc wide, and contains three CO-bright knots. Across eight independent transverse cuts, the adjacent Hα ridge is displaced preferentially to one side of the principal CO ridge by a median 10.0^+0.9_−1.4 pc. Young OB candidates are more closely associated with Hα than with compact CO. The filament shows little velocity change along its length but a resolved gradient across its minor axis. Its elongated morphology, transverse kinematics, and ordered CO-Hα distribution are consistent with locally asymmetric molecular-gas compression and subsequent massive star formation. Across the wider field, 23 well-measured compact clumps have a median radius of 2.67 pc and a median velocity dispersion of 2.15 km s^−1. Their linewidth and apparent virial-parameter distributions show no clear difference between the SE filament and the rest of the field. Although the local spiral potential and pattern speed remain unconstrained, the observations provide a resolved view of a compression-compatible molecular-to-ionized-gas sequence in the center of M33.
ER -