Probing Metallicity across the Galactic Disk with the GBTDana S. Balser (NRAO)
L.D. Anderson (WVU), T.M. Bania (BU), & T.V. Wenger (BU)
Photo: Harry Morton
HII Region Electron Temperature and Metallicity
Shaver+ (1983)
1.15e
C
L T TT
RRL and free-free continuum emissionin LTE at 3 cm.
HII Region Sample
GBT+ 140 Foot
Quireza+ (2006); Balser+ (2011)
Sun
GC 18 HRDS
Electron Temperature Radial Gradient
K) 200 )(T K; 889 (rms
R)36359()3795222(T
e
gale
Electron Temperature Azimuthal Structure
K 480 :IntervalK 124806240 :Range
:Contours
GBT Sample
O/H Radial Gradient
013.0058.0
0039.00339.0
0063.00602.0
Slope (dex/kpc)
013.0080.0
Summary
• HRDS Probes Metallicity Across the Galaxy• Azimuthal Structure• O/H radial gradients: -0.03 to -0.08 dex/kpc
Questions
Extra Slides
GBT/140 Foot Cross Calibration
Balser+ (2011)
Open Cluster Data
Balser+ (2011)
O/H Radial Gradient - GBT