1998/09/27 by R. D. Blum, A. Damineli · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Emission spectrum #Galactic Center #Galaxy #H II region #Infrared #Ionization #Sagittarius #Sagittarius A* #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/306744
23 pages, 12 figures, AASTEX, ApJ accepted
arxiv created 1998/09/27 · openalex publication_date 1999/02/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present 2 μm narrowband images of the core H II region in the Galactic star-forming region Sagittarius D. The emission-line images are centered on 2.17 μm (Brγ) and 2.06 μm (He I). The H II region appears at the edge of a well-defined dark cloud, and the morphology suggests a blister geometry as pointed out in earlier radio continuum work. There is a deficit of stars in general in front of the associated dark cloud indicating the H II region is located in between the Galactic center and the Sun. The lesser spatial extent of the He I line emission relative to Brγ places the effective temperature of the ionizing radiation field below 40,000 K. The He I 2.06 μm to Brγ ratio and Brγ/far-infrared dust emission put T eff at about 36,500-40,000 K as derived from ionization models.