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Title: MAPPING THE X-SHAPED MILKY WAY BULGE

Abstract

We analyzed the distribution of the red clump (RC) stars throughout the Galactic bulge using Two Micron All Sky Survey data. We mapped the position of the RC in 1 deg{sup 2} fields within the area |l| {<=} 8.{sup 0}5 and 3.{sup 0}5 {<=} |b| {<=} 8.{sup 0}5, for a total of 170 deg{sup 2}. The single RC seen in the central area splits into two components at high Galactic longitudes in both hemispheres, produced by two structures at different distances along the same line of sight. The X-shape is clearly visible in the Z-X plane for longitudes close to the l = 0{sup 0} axis. Crude measurements of the space densities of RC stars in the bright and faint RC populations are consistent with the adopted RC distances, providing further supporting evidence that the X-structure is real, and that there is approximate front-back symmetry in our bulge fields. We conclude that the Milky Way bulge has an X-shaped structure within |l| {approx}< 2{sup 0}, seen almost edge-on with respect to the line of sight. Additional deep near-infrared photometry extending into the innermost bulge regions combined with spectroscopic data is needed in order to discriminate among the different possibilities thatmore » can cause the observed X-shaped structure.« less

Authors:
; ;  [1];  [2];  [3];  [4]
  1. Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago 22 (Chile)
  2. Observatories of the Carnegie Institute of Washington, Pasadena, CA 91101-1292 (United States)
  3. European Southern Observatory, D-85748 Garching (Germany)
  4. Universite de Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, B.P. 4229, 06304 Nice Cedex 4 (France)
Publication Date:
OSTI Identifier:
21582950
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (New York, N.Y. Online)
Additional Journal Information:
Journal Volume: 142; Journal Issue: 3; Other Information: DOI: 10.1088/0004-6256/142/3/76; Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; DISTANCE; MAPPING; MILKY WAY; PHOTOMETRY; STARS; SYMMETRY; CALCULATION METHODS; GALAXIES

Citation Formats

Saito, R. K., Zoccali, M., Minniti, D., McWilliam, A., Gonzalez, O. A., and Hill, V., E-mail: rsaito@astro.puc.cl, E-mail: mzoccali@astro.puc.cl, E-mail: dante@astro.puc.cl, E-mail: andy@obs.carnegiescience.edu, E-mail: ogonzale@eso.org, E-mail: vanessa.hill@oca.eu. MAPPING THE X-SHAPED MILKY WAY BULGE. United States: N. p., 2011. Web. doi:10.1088/0004-6256/142/3/76.
Saito, R. K., Zoccali, M., Minniti, D., McWilliam, A., Gonzalez, O. A., & Hill, V., E-mail: rsaito@astro.puc.cl, E-mail: mzoccali@astro.puc.cl, E-mail: dante@astro.puc.cl, E-mail: andy@obs.carnegiescience.edu, E-mail: ogonzale@eso.org, E-mail: vanessa.hill@oca.eu. MAPPING THE X-SHAPED MILKY WAY BULGE. United States. doi:10.1088/0004-6256/142/3/76.
Saito, R. K., Zoccali, M., Minniti, D., McWilliam, A., Gonzalez, O. A., and Hill, V., E-mail: rsaito@astro.puc.cl, E-mail: mzoccali@astro.puc.cl, E-mail: dante@astro.puc.cl, E-mail: andy@obs.carnegiescience.edu, E-mail: ogonzale@eso.org, E-mail: vanessa.hill@oca.eu. Thu . "MAPPING THE X-SHAPED MILKY WAY BULGE". United States. doi:10.1088/0004-6256/142/3/76.
@article{osti_21582950,
title = {MAPPING THE X-SHAPED MILKY WAY BULGE},
author = {Saito, R. K. and Zoccali, M. and Minniti, D. and McWilliam, A. and Gonzalez, O. A. and Hill, V., E-mail: rsaito@astro.puc.cl, E-mail: mzoccali@astro.puc.cl, E-mail: dante@astro.puc.cl, E-mail: andy@obs.carnegiescience.edu, E-mail: ogonzale@eso.org, E-mail: vanessa.hill@oca.eu},
abstractNote = {We analyzed the distribution of the red clump (RC) stars throughout the Galactic bulge using Two Micron All Sky Survey data. We mapped the position of the RC in 1 deg{sup 2} fields within the area |l| {<=} 8.{sup 0}5 and 3.{sup 0}5 {<=} |b| {<=} 8.{sup 0}5, for a total of 170 deg{sup 2}. The single RC seen in the central area splits into two components at high Galactic longitudes in both hemispheres, produced by two structures at different distances along the same line of sight. The X-shape is clearly visible in the Z-X plane for longitudes close to the l = 0{sup 0} axis. Crude measurements of the space densities of RC stars in the bright and faint RC populations are consistent with the adopted RC distances, providing further supporting evidence that the X-structure is real, and that there is approximate front-back symmetry in our bulge fields. We conclude that the Milky Way bulge has an X-shaped structure within |l| {approx}< 2{sup 0}, seen almost edge-on with respect to the line of sight. Additional deep near-infrared photometry extending into the innermost bulge regions combined with spectroscopic data is needed in order to discriminate among the different possibilities that can cause the observed X-shaped structure.},
doi = {10.1088/0004-6256/142/3/76},
journal = {Astronomical Journal (New York, N.Y. Online)},
issn = {1538-3881},
number = 3,
volume = 142,
place = {United States},
year = {2011},
month = {9}
}