A Puzzle Involving Galactic Bulge Microlensing Events

Abstract

We study a sample of 16 microlensed Galactic bulge main sequence turnoff region stars for which high dispersion spectra have been obtained with detailed abundance analyses. We demonstrate that there is a very strong and highly statistically significant correlation between the maximum magnification of the microlensed bulge star and the value of the [Fe/H] deduced from the high resolution spectrum of each object. Physics demands that this correlation, assuming it to be real, be the result of some sample bias. We suggest several possible explanations, but are forced to reject them all,and are left puzzled. To obtain a reliable metallicity distribution in the Galactic bulge based on microlensed dwarf stars it will be necessary to resolve this issue through the course of additional observations.

Submitted to ApJL, table 2 (quite long) will only appear in the on-line version of ApJL

References in corpus (9)

• Discovery of a Jupiter/Saturn Analog with Gravitational Microlensing
• Microlens OGLE-2005-BLG-169 Implies Cool Neptune-Like Planets are Common
• The First Detailed Abundances for M giants in the inner Bulge from Infrared Spectroscopy
• Chemical Composition of Faint (I~21 mag) Microlensed Bulge Dwarf OGLE-2007-BLG-514S
• Clues to the Metallicity Distribution in the Galactic Bulge: Abundances in OGLE-2007_BLG-349S
• A High-Resolution Spectrum of the Highly Magnified Bulge G-Dwarf MOA-2006-BLG-099S
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. Detailed abundance analysis of OGLE-2008-BLG-209S
• Clues to the Metallicity Distribution in the Galactic Bulge: Abundances in MOA-2008-BLG310 and MOA-2008-BLG311
• OGLE-2009-BLG-076S - The most metal-poor dwarf star in the Galactic bulge

Cited by in corpus (11)

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• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. IV. Two bulge populations
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky Way
• Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. II. Ages, metallicities, detailed elemental abundances, and connections to the Galactic thick disc
• The Terzan 5 puzzle: discovery of a third, metal-poor component
• The Ages of Galactic Bulge Stars with Realistic Uncertainties
• The Controversial Star-Formation History and Helium Enrichment of the Milky Way Bulge
• Planetary mass function and planetary systems
• Chemically-dissected rotation curves of the Galactic Bulge from Main Sequence proper motions
• Simulating the Role of Stellar Rotation in the Spectroscopic Effects of Differential Limb Magnification