THE APACHE POINT OBSERVATORY GALACTIC EVOLUTION EXPERIMENT: FIRST DETECTION OF HIGH-VELOCITY MILKY WAY BAR STARS

Journal Article · Mon Aug 20 00:00:00 EDT 2012 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/755/2/L25· OSTI ID:22047599

Nidever, David L; Zasowski, Gail; Majewski, Steven R; Beaton, Rachael L; Wilson, John C; Skrutskie, Michael F; O'Connell, Robert W ^[1]; Bird, Jonathan; Schoenrich, Ralph; Johnson, Jennifer A; Sellgren, Kris ^[2]; Robin, Annie C; Schultheis, Mathias ^[3]; Martinez-Valpuesta, Inma; Gerhard, Ortwin ^[4]; Shetrone, Matthew ^[5]; Schiavon, Ricardo P ^[6]; Weiner, Benjamin ^[7]; Schneider, Donald P ^[8]; others, and

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1. Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)
2. Department of Astronomy and the Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210 (United States)
3. Institut Utinam, CNRS UMR 6213, OSU THETA, Universite de Franche-Comte, 41bis avenue de l'Observatoire, F-25000 Besancon (France)
4. Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstrasse, D-85748 Garching (Germany)
5. McDonald Observatory, University of Texas at Austin, Fort Davis, TX 79734 (United States)
6. Gemini Observatory, 670 North A'Ohoku Place, Hilo, HI 96720 (United States)
7. Steward Observatory, 933 North Cherry Street, University of Arizona, Tucson, AZ 85721 (United States)
8. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

Commissioning observations with the Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of the Sloan Digital Sky Survey III, have produced radial velocities (RVs) for {approx}4700 K/M-giant stars in the Milky Way (MW) bulge. These high-resolution (R {approx} 22, 500), high-S/N (>100 per resolution element), near-infrared (NIR; 1.51-1.70 {mu}m) spectra provide accurate RVs ({epsilon}{sub V} {approx} 0.2 km s{sup -1}) for the sample of stars in 18 Galactic bulge fields spanning -1 Degree-Sign -32 Degree-Sign . This represents the largest NIR high-resolution spectroscopic sample of giant stars ever assembled in this region of the Galaxy. A cold ({sigma}{sub V} {approx} 30 km s{sup -1}), high-velocity peak (V{sub GSR} Almost-Equal-To +200 km s{sup -1}) is found to comprise a significant fraction ({approx}10%) of stars in many of these fields. These high RVs have not been detected in previous MW surveys and are not expected for a simple, circularly rotating disk. Preliminary distance estimates rule out an origin from the background Sagittarius tidal stream or a new stream in the MW disk. Comparison to various Galactic models suggests that these high RVs are best explained by stars in orbits of the Galactic bar potential, although some observational features remain unexplained.

• OSTI ID: 22047599
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 755; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
COMPARATIVE EVALUATIONS
DETECTION
DISTANCE
GALACTIC EVOLUTION
GIANT STARS
MILKY WAY
NEAR INFRARED RADIATION
ORBITS
RADIAL VELOCITY
RESOLUTION