HII Region Metallicity Distribution in the Milky Way Disk

Details HII Region Metallicity Distribution in the Milky Way Disk HII Region Metallicity Distribution in the Milky Way Disk

2011-06-08

arxiv.org/abs/1106.1660v1

Astronomy and Astrophysics

Astrophysics

Galaxy Astrophysics

Accepted for publication in ApJ

Scientific paper

The distribution of metals in the Galaxy provides important information about galaxy formation and evolution. HII regions are the most luminous objects in the Milky Way at mid-infrared to radio wavelengths and can be seen across the entire Galactic disk. We used the NRAO Green Bank Telescope (GBT) to measure radio recombination line and continuum emission in 81 Galactic HII regions. We calculated LTE electron temperatures using these data. In thermal equilibrium metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. Our HII region distribution covers a large range of Galactocentric radius (5 to 22 kpc) and samples the Galactic azimuth range 330 degree to 60 degree. Using our highest quality data (72 objects) we derived an O/H Galactocentric radial gradient of -0.0383 +/- 0.0074 dex/kpc. Combining these data with a similar survey made with the NRAO 140 Foot telescope we get a radial gradient of -0.0446 +/- 0.0049 dex/kpc for this larger sample of 133 nebulae. The data are well fit by a linear model and no discontinuities are detected. Dividing our sample into three Galactic azimuth regions produced significantly different radial gradients that range from -0.03 to -0.07 dex/kpc. These inhomogeneities suggest that metals are not well mixed at a given radius. We stress the importance of homogeneous samples to reduce the confusion of comparing data sets with different systematics. Galactic chemical evolution models typically derive chemical evolution along only the radial dimension with time. Future models should consider azimuthal evolution as well.

Affiliated with

Also associated with

No associations

Rating

HII Region Metallicity Distribution in the Milky Way Disk does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with HII Region Metallicity Distribution in the Milky Way Disk, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HII Region Metallicity Distribution in the Milky Way Disk will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-578452