EDP Sciences
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Volume 433, Number 1, April I 2005
Page(s) 173 - 183
Section Galactic structure, stellar clusters and populations
DOI http://dx.doi.org/10.1051/0004-6361:20041255

A&A 433, 173-183 (2005)
DOI: 10.1051/0004-6361:20041255

The thick disc component of the Galaxy from near infrared colour-magnitude diagrams

A. Cabrera-Lavers1, F. Garzón1, 2 and P. L. Hammersley1

1  Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
    e-mail: acabrera@ll.iac.es
2  Departamento de Astrofísica, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain

(Received 7 May 2004 / Accepted 8 December 2004)

The vertical distribution of K giants stars is analyzed using 2MASS data and a semiempirical method of extracting stellar densities from the K/J-K colour-magnitude diagrams. The vertical density distribution of red clump giant stars can be described by a double exponential, with scaleheights of 268.81 $\pm$ 12.65 pc and 1061.9 $\pm$ 52.16 pc. These values are in agreement with the expected values for the thin and thick disc components of the Milky Way. For the thick disc, the radial scalelength is also obtained, with a value of hR = 3.04 $\pm$ 0.11 kpc.

Key words: Galaxy: general -- Galaxy: stellar content -- Galaxy: structure -- infrared: stars -- Galaxy: disk

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