Investigating star formation scenarios in the Milky Way using YSO distributions -- A pilot study

TL;DR

This study examines young stellar object distributions in nine star-forming regions of the Milky Way to explore star formation mechanisms and regional differences, revealing evidence of triggered and spontaneous star formation influenced by galactic location.

Contribution

It provides new insights into the spatial distribution of YSOs and their relation to star formation scenarios across different galactic regions, highlighting regional variations.

Findings

Sh2-22 and Sh2-19 show signs of triggered star formation.

Outer Galaxy regions have fewer older stars and more Class I YSOs.

Inner Galaxy regions have higher Transition Disk percentages.

Abstract

We investigated the distributions of classified young stellar object (YSO) in nine star-forming regions associated with Hii regions, namely Sh2-22, Sh2-19, Sh2-17, M16, M8, IC5070, Sh2-252, NGC2467 and M42, as a means of exploring the star formation scenarios (triggered or spontaneous) in the various regions. The YSO distributions of nine regions along the galactic longitudes and across different spiral arms were explored. It is noted that Sh2-22 and Sh2-19 may have evidence of localized triggered star formation, whereas Sh2-17 may be a spontaneous star forming region. The results showed that the location within the Milky Way may influence localized triggered star formation within individual regions. There is strong evidence that there are fewer older stars (Transition Disks) within the Outer regions of the Galaxy (2.91 +- 1.74%), accompanied by a higher number of Class I (32.49 +- 10.77%). This is different from the Inner Galactic regions where the Transition Disks are higher (32.93 +- 13.78%) as compared to low Class I sources (11.01 +- 4.81%). The number of Class II stars is relatively high and increases from the Inner regions (52.64 +- 10.07%) to Outer regions (64.54 +- 11.09%). These nine star-forming regions are not an accurate representation of locations throughout the Galaxy and the results may be biased.