HII Region Discover Survey

The HII Region Discovery Survey (HRDS) is a Green Bank Telescope survey of recombination line and continuum emission at X-band (9 GHz, 3 cm). It extends from 343 deg < l < 67 deg, |b| < 1 deg. The 448 detected regions have doubled the number of HII regions known in this part of the Galaxy and are the most distant Galactic HII regions detected to date.

Below are data from HRDS. Left: GBT HRDS RRL spectra for four new HII regions. Shown are the average spectra for seven RRL transitions, H87alpha to H93alpha, smoothed to 1.86 km/s resolution. Kinematic distances to these nebulae were resolved using the RRL velocity and HI maps to study HI absorption of the HII region's continuum emission. The brightest HII regions show He and C recombination lines. Right: Spitzer 24 micron MIPSGAL infrared images for the same sources, together with contours of VGPS 20 cm continuum emission (1 arcmin resolution). Contours are drawn at 80%, 60%, and 40% of the peak emission. All images are 5 arcmin squares; each scale bar is 5 pc long. The GBT 82 arcsec (HPBW) beam is shown as a hatched circle. (See Anderson et al. 2011.)

The HRDS team members are Loren Anderson (West Virginia University), Thomas Bania (Boston University), Dana Balser (NRAO), and Bob Rood (University of Virginia).

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