THE METALLICITY DISTRIBUTION FUNCTIONS OF SEGUE G AND K DWARFS: CONSTRAINTS FOR DISK CHEMICAL EVOLUTION AND FORMATION
- Research School of Astronomy and Astrophysics, Australian National University, Weston, ACT 2611 (Australia)
- Department of Astronomy, The Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States)
- UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
- Tombaugh Fellow, Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)
- Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States)
- Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)
- Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, East Lansing, MI 48824 (United States)
- Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)
- Department of Astronomy and Astrophysics, Penn State University, 408A Davey Laboratory, University Park, PA 16802 (United States)
- Laboratorio Interinstitucional de e-Astronomia (LIneA), Rua Gal. Jose Cristino 77, 20921-400 Rio de Janeiro (Brazil)
- Leibniz-Institut fuer Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)
We present the metallicity distribution function (MDF) for 24,270 G and 16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic plane, based on spectroscopy from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) survey. This stellar sample is significantly larger in both number and volume than previous spectroscopic analyses, which were limited to the solar vicinity, making it ideal for comparison with local volume-limited samples and Galactic models. For the first time, we have corrected the MDF for the various observational biases introduced by the SEGUE target-selection strategy. SEGUE is particularly notable for its sample of K dwarfs, which are too faint to examine spectroscopically far from the solar neighborhood. The MDF of both spectral types becomes more metal-poor with increasing |Z|, which reflects the transition from a sample with small [{alpha}/Fe] values at small heights to one with enhanced [{alpha}/Fe] above 1 kpc. Comparison of our SEGUE distributions to those of two different Milky Way models reveals that both are more metal-rich than our observed distributions at all heights above the plane. Our unbiased observations of G and K dwarfs provide valuable constraints over the |Z|-height range of the Milky Way disk for chemical and dynamical Galaxy evolution models, previously only calibrated to the solar neighborhood, with particular utility for thin- and thick-disk formation models.
- OSTI ID:
- 22139936
- Journal Information:
- Astrophysical Journal, Vol. 761, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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