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Estimation of Galactic Model Parameters in High Latitudes with SDSS

Published online by Cambridge University Press:  05 March 2013

S. Bilir*
Affiliation:
Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul, Turkey
A. Cabrera-Lavers
Affiliation:
Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain GTC Project Office, E-38205 La Laguna, Tenerife, Spain
S. Karaali
Affiliation:
Beykent University, Faculty of Science and Letters, Department of Mathematics and Computing, Ayazağa 34396, Istanbul, Turkey
S. Ak
Affiliation:
Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul, Turkey
E. Yaz
Affiliation:
Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul, Turkey
M. López-Corredoira
Affiliation:
Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain
*
E Corresponding author. Email: sbilir@istanbul.edu.tr
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Abstract

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We estimated the Galactic model parameters for a set of 36 high-latitude fields included in the currently available Data Release 5 (DR 5) of the Sloan Digital Sky Survey (SDSS), to explore their possible variation with the Galactic longitude. The thick disc scaleheight moves from ∼550 pc at 120 < l < 150° to ∼720 pc at 250 < l < 290°, while the thin disc scaleheight is as large as ∼195 pc in the anticenter direction and ∼15% lower at |l| < 30°. Finally, the axis ratio (c/a) of the halo changes from a mean value of ∼0.55 in the two first quadrants of the Galaxy to ∼0.70 at 190 < l < 300°. For the halo, the reason for the dependence of the model parameters on the Galactic longitude arises from the well known asymmetric structure of this component. However, the variation of the model parameters of the thin and thick discs with Galactic longitude originates from the gravitational effect of the Galactic long bar. Moreover, the excess of stars in quadrant I (quadrant III) over quadrant IV (quadrant II) is in agreement with this scenario.

Information

Type
Research Article
Copyright
Copyright © Astronomical Society of Australia 2008