Volume 571, November 2014
|Number of page(s)||5|
|Section||Galactic structure, stellar clusters and populations|
|Published online||14 November 2014|
Milky Way demographics with the VVV survey⋆
III. Evidence for a great dark lane in the 157 million star bulge color–magnitude diagram
Departamento de Ciencias FísicasUniversidad Andrés Bello,
República 220, 837-0134
2 Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Casilla 306, Santiago 22, Chile
3 Millennium Institute of Astrophysics, Av. Vicuña Mackenna 4860, 782-0436 Macul Santiago, Chile
4 Vatican Observatory, 00120 Vatican City State, Italy
5 Universidade Federal de Sergipe, Departamento de Física, Av. Marechal Rondon s/n, 49100-000 São Cristóvão, SE, Brazil
6 European Southern Observatory, 19001 Casilla Santiago 19, Chile
7 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
8 Department of Physics, University of Wisconsin, Whitewater, WI 53190, USA
9 Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
10 Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
11 Université de Nice-Sophia-Antipolis, CNRS, Observatoire de Côte d’Azur, Laboratoire Lagrange, 06304 Nice Cedex 4, France
Received: 24 April 2014
Accepted: 17 September 2014
The new generation of IR surveys are revealing and quantifying Galactic features that provide an improved 3D interpretation of our own Galaxy. We present an analysis of the global distribution of dust clouds in the bulge using the near-IR photometry of 157 million stars from the VVV survey. We investigate the color−magnitude diagram of the Milky Way bulge, which shows a red giant clump of core He burning stars that is split into two color components, with a mean color difference of (Z − Ks) = 0.55 mag that is equivalent to AV = 2.0 mag. We conclude that there is an optically thick dust lane at intermediate latitudes above and below the plane that stretches across several square degrees from l = −10° to l = +10°. We call this feature the great dark lane. Although its exact distance is uncertain, it is located in front of the bulge. The evidence for a large-scale great dark lane within the Galactic bulge is important for constraining models of the barred Milky Way bulge and for comparing our galaxy with external barred galaxies in which these types of features are prominent. We discuss two other potential implications of the great dark lane for microlensing and bulge stellar populations studies.
Key words: Galaxy: center / Galaxy: structure / stars: late-type / dust, extinction / surveys
© ESO, 2014
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