Photo: Harry Morton

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