EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 428/3 Article
Free access article

Issue A&A
Volume 428, Number 3, December IV 2004
Page(s) 891 - 903
Section Galactic structure, stellar clusters and populations
DOI http://dx.doi.org/10.1051/0004-6361:20041218



A&A 428, 891-903 (2004)
DOI: 10.1051/0004-6361:20041218

3D outer bulge structure from near infrared star counts

S. Picaud1, 2 and A. C. Robin1

1  CNRS UMR6091, Observatoire de Besançon, BP 1615, 25010 Besançon Cedex, France
    e-mail: [picaud;annie.robin]@obs-besancon.fr
2  Astronomisches Rechen-Institut, Mönchhofstraße 12-14, 69120 Heidelberg, Germany
    e-mail: picaud@ari.uni-heidelberg.de

(Received 3 May 2004 / Accepted 13 June 2004 )

Abstract
We attempt to study the characteristics of the different stellar populations present in the Galactic central region. A Monte Carlo method is used to simultaneously fit 11 thin disc and triaxial outer bulge density parameters on ( $K_{\rm s}$, $J-K_{\rm s}$) star count data in almost 100 windows from the DENIS near infrared large scale survey at -8°  < l  < 12° and | b |  < 4°. Various bulge density profiles and luminosity functions were tested using a population synthesis scheme. The best models, selected by a maximum likelihood test, give the following description: the outer bulge is boxy, prolate, and oriented 10.6°  $\pm$ 3° with respect to the Sun-center direction. It seems that the main bulge population is not older than 10 Gyr, but this preliminary result needs further work to be confirmed. A significant central hole is found in the middle of the thin disc. We discuss these results in regard to previous findings and the scenario of bulge formation.


Key words: Galaxy: structure -- Galaxy: stellar content -- Galaxy: bulge -- Galaxy: disk

SIMBAD Objects



© ESO 2004


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.