Volume 584, December 2015
|Number of page(s)||5|
|Section||Stellar structure and evolution|
|Published online||18 November 2015|
Evidence for a metal-poor population in the inner Galactic bulge
1 Laboratoire Lagrange, Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Bvd de l’Observatoire, 06304 Nice, France
2 Observat’orio Nacional, 77 Sao Cristóvao, 20921-400 Rio de Janeiro, Brazil
3 Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
4 NSF Astronomy & Astrophysics Postdoctoral Fellow
5 Instituto de Astrofísica de Canarias, Calle Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
6 Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
7 National Optical Astronomy Observatories, Tucson, AZ 85719, USA
8 Departamento de Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
9 Department of Astronomy, University of Virginia, Charlottesville, 3530 McCormick Road, VA 22904-4325, USA
10 Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
11 Laboratǿrio Interinstitucional de e-Astronomia, – LIneA, Rua Gal. Joseé Cristino 77, 20921-400 Rio de Janeiro, Brazil
12 Apache Point Observatory and New Mexico State University, PO Box 59, Sunspot, NM, 88349-0059, USA
13 Sternberg Astronomical Institute, Moscow State University, 119992 Moscow, Russia
14 University of Texas at Austin, 32 Fowlkes Rd, McDonald Observatory, Tx 79734-3005, USA
Received: 21 July 2015
Accepted: 16 October 2015
The inner Galactic bulge has, until recently, been avoided in chemical evolution studies because of extreme extinction and stellar crowding. Large, near-IR spectroscopic surveys, such as the Apache Point Observatory Galactic Evolution Experiment (APOGEE), for the first time allow the measurement of metallicities in the inner region of our Galaxy. We study metallicities of 33 K/M giants situated in the Galactic center region from observations obtained with the APOGEE survey. We selected K/M giants with reliable stellar parameters from the APOGEE/ASPCAP pipeline. Distances, interstellar extinction values, and radial velocities were checked to confirm that these stars are indeed situated in the inner Galactic bulge. We find a metal-rich population centered at [M/H] = +0.4 dex, in agreement with earlier studies of other bulge regions, but we also discovered a peak at low metallicity around [M/H] = −1.0 dex. This finding suggests the presence of a metal-poor population, which has not previously been detected in the central region. Our results indicate a dominant metal-rich population with a metal-poor component that is enhanced in the α-elements. This metal-poor population may be associated with the classical bulge and a fast formation scenario.
Key words: Galaxy: bulge / stars: fundamental parameters / stars: abundances / Galaxy: stellar content
© ESO, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.