The Extended Emission of Ultracompact HII Regions: An Overview and New Observations

Ultracompact (UC) HII regions with Extended Emission (EE) are classical UC HII regions associated with much larger ( > 1') structures of ionized gas. The efforts to investigate, detect, and understand if the EE is physically related with the UC emission are few. If they are related, our understanding of UC HII regions may be affected (e.g., in the estimation of ionizing UV photons). Here we present a brief overview of UC HII regions with EE (UC HII+EE) including our most recent effort aimed at searching for UC HII regions associated with extended emission.