演講資訊

摘要：

Dust and gas are concentrated in spiral arms of galaxies, where enhanced gas densities and gravitational instabilities promote star formation. Giant molecular clouds, massive OB stars, OB associations, young open clusters, pre-main sequence stars, and classical Cepheids are key tracers of spiral structures. Because many of these objects are relatively young, they generally remain close to their birthplaces. However, spiral arms may not always form continuous, well-defined structures, and mapping the Milky Way’s spiral morphology is particularly challenging because we observe the Galaxy within its disc. In this talk, I will present the recent study by Ferreira et al. (2026), which used Gaia DR3 to search for open clusters towards the Galactic anticentre, particularly in the direction of the ‘hole’ on Perseus arm. The newly discovered OCs significantly increased the cluster census in Galactic outer region, whereas these clusters may not belong to the Perseus arm and may be associated with Outer Norma arm. These findings suggest that this ‘hole’ in the Perseus arm may reflect low star-formation activity, dust obscuration, or an intrinsically fragmented spiral structure.

期刊：

Ferreira et al. 2026, MNRAS, 548, 2, stag621 “New star clusters discovered towards the Galactic anticentre direction using Gaia DR3 data” (https://doi.org/10.1093/mnras/stag621)