Properties of the Compact HII Region Complex G-0.02-0.07

TL;DR

This study provides detailed extinction maps and high-resolution images of the G-0.02-0.07 HII region complex near the Galactic center, revealing insights into its structure, star formation activity, and relative positioning within the molecular cloud.

Contribution

The paper offers new high-resolution Paschen alpha images and extinction measurements of G-0.02-0.07, enhancing understanding of its structure and star formation status.

Findings

Regions A, B, and C have similar foreground extinctions, indicating they are on the near side of the molecular cloud.

Region D exhibits higher extinction, suggesting it is younger and embedded within a dense core.

The extinction measurements imply the regions are part of recent star formation episodes near the Galactic center.

Abstract

We present new extinction maps and high-resolution Paschen alpha images of G-0.02-0.07, a complex of compact HII regions located adjacent to the M-0.02-0.07 giant molecular cloud, 6 parsecs in projection from the center of the Galaxy. These HII regions, which lie in projection just outside the boundary of the Sgr A East supernova remnant, represent one of the most recent episodes of star formation in the central parsecs of the Galaxy. The 1.87 micron extinctions of regions A, B and C are almost identical, approximately 1.5 magnitudes. Region D, in contrast, has a peak 1.87 micron extinction of 2.3 magnitudes. Adopting the Nishiyama et al. (2008) extinction law, we find these extinctions correspond to visual extinctions of A_V = 44.5 and A_V = 70, respectively. The similar and uniform extinctions of regions A, B and C are consistent with that expected for foreground extinction in the direction of the Galactic center, suggesting that they lie at the front side of the M-0.02-0.07 molecular cloud. Region D is more compact, has a higher extinction and is thus suspected to be younger and embedded in a dense core in a compressed ridge on the western edge of this cloud.