Spectroscopy and Abundances of 88 K Giants in Baade's Window
Abstract
Spectroscopy and photometry is presented for 112 stars in Baade's window (l = 1°, b = -4°) and for 63 galactic disk and globular cluster comparison K giants. Adopting a galactocentric distance of 7.5 kpc, the Baade's window bulge population lies ≈500 pc below the plane. This paper reports line strengths for 34 features measured from 5-Å-resolution spectra. In the strongest-lined bulge giants, strong Fe, Mg, and Na lines are enhanced in lockstep relative to the solar-neighborhood metal-rich giants. Clumps of weak iron lines on the linear portion of the curve of growth are as enhanced as the strong lines. Other physical characteristics of the bulge giants are found to be approximately normal. Abundances for 88 bulge K giants are derived. The resulting abundance distribution runs from -1 to nearly +1 dex, and 37 of the 88 stars exceed twice the solar abundance. The mean abundance is 1.96 times the solar value, with quartiles at 0.6 and 2.7 times the solar abundance. Of the 88 stars with derived abundances, approximately 20% exceed the abundance of the most metal-rich local K giants; 50% exceed the solar abundance, and 10% are metal poor (< -0.6 dex). The author concludes that the strong-lined giants in the nuclear bulge are enhanced in metals relative to the metal-rich solar-neighborhood giants. He asserts that similar enhancements seen in "super metal-rich" stars and old galaxy populations are also due to genuinely high metal abundance.
- Publication:
-
The Astronomical Journal
- Pub Date:
- March 1988
- DOI:
- 10.1086/114681
- Bibcode:
- 1988AJ.....95..828R
- Keywords:
-
- Astronomical Models;
- Disk Galaxies;
- Giant Stars;
- Globular Clusters;
- K Stars;
- Stellar Spectra;
- Color-Magnitude Diagram;
- Dwarf Stars;
- Galactic Bulge;
- Metallic Stars;
- Solar Neighborhood;
- Spectral Resolution;
- Astrophysics;
- STARS: ABUNDANCES;
- STARS: SPECTRAL CLASSIFICATION