Young Stars at the Edge: Stellar Clustering in the Outer Regions of the M33 Disk

Abstract

We investigate the distribution of bright main sequence stars near the northern edge of the M33 disk. Clustering on sub-kpc scales is seen among stars with ages near 10 Myr, and two large star-forming complexes are identified. Similar large-scale grouping is not evident among stars with ages 100 Myr. These stars are also distributed over a much larger area than those with younger ages, and it is argued that random stellar motions alone, as opposed to orderly motions of the type spurred by large scale secular effects, can re-distribute stars out to distances of at least 2 kpc (i.e. one disk scale length) from their birth places on 100 Myr timescales. Such random motions may thus play a significant role in populating the outer regions of the M33 disk. Finally, it is suggested that - to the extent that the ambient properties of the outer disk mirror those in the main body of the disk - stars in this part of M33 may have formed in star clusters with masses 50 - 250 solar, which is substantially lower than the peak of the solar neighborhood initial cluster mass function.

ApJ (Letters), accepted for publication

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Cited by in corpus (8)

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• Dynamical signatures of a LCDM-halo and the distribution of the baryons in M33
• PHANGS-HST: Star Cluster Spectral Energy Distribution Fitting with CIGALE
• The population of Young Stellar Clusters throughout the disk of M33
• The Young Open Clusters King 12, NGC 7788, and NGC 7790: Pre-Main Sequence Stars and Extended Stellar Halos
• Star Cluster Populations in the Outer Disks of Nearby Galaxies
• Seeing Red in M32: Constraints on the Stellar Content from Near- and Mid-Infrared Observations and Applications for Studies of More Distant Galaxies
• The Stellar Archeology of the M33 Disk: Recent Star-Forming History and Constraints on the Timing of an Interaction with M31