The First Detection of Blue Straggler Stars in the Milky Way Bulge

Abstract

We report the first detections of Blue Straggler Stars (BSS) in the bulge of the Milky Way galaxy. Proper motions from extensive space-based observations along a single sight-line allow us to separate a sufficiently clean and well-characterized bulge sample that we are able to detect a small population of bulge objects in the region of the color-magnitude diagram commonly occupied young objects and blue strgglers. However, variability measurements of these objects clearly establish that a fraction of them are blue stragglers. Out of the 42 objects found in this region of the color-magnitude diagram, we estimate that at least 18 are genuine BSS. We normalize the BSS population by our estimate of the number of horizontal branch stars in the bulge in order to compare the bulge to other stellar systems. The BSS fraction is clearly discrepant from that found in stellar clusters. The blue straggler population of dwarf spheroidals remains a subject of debate; some authors claim an anticorrelation between the normalised blue straggler fraction and integrated light. If this trend is real, then the bulge may extend it by three orders of magnitude in mass. Conversely, we find that the genuinely young (~5Gy or younger) population in the bulge, must be at most 3.4% under the most conservative scenario for the BSS population.

ApJ in press; 25 pages, 6 figures, 2 tables

References in corpus (13)

• Two Red Clumps and the X-Shaped Milky Way Bulge
• The Split Red Clump of the Galactic Bulge from OGLE-III
• Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry
• Transiting extrasolar planetary candidates in the Galactic bulge
• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process
• Formation & evolution of the Galactic bulge: constraints from stellar abundances
• OGLE-III Detection of the Anomalous Galactic Bulge Red Giant Branch Bump: Evidence of Enhanced Helium Enrichment
• Primordial Binary Evolution and Blue Stragglers
• Blue straggler stars in dwarf spheroidal galaxies
• The surprising external upturn of the Blue Straggler radial distribution in M55
• Search and analysis of blue straggler stars in open clusters
• A Galactic Center Origin for HE 0437-5439, the Hypervelocity Star near the Large Magellanic Cloud
• Photometric Oscillations of Low Luminosity Red Giant Stars

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