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2MASS Star Counts and Galactic Structure

Published online by Cambridge University Press:  13 May 2016

D. K. Ojha*
Affiliation:
Tata Institute of Fundamental Research, Mumbai, 400 005 India

Abstract

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This paper presents a global analysis of the first 2MASS (Two Micron All Sky Survey) data as observed in seven fields at different Galactic latitudes. These new data lead to strong constraints on the radial structure of the Galactic thin and thick disks. The interpretation of star counts and color distributions of stars in the near-infrared with a synthetic stellar population model provides strong evidence that the Galactic thin disk density scale length, hR, is rather short (2.8±0.3 kpc). The Galactic thick disk population is revisited in the light of new data. We find the thick disk to have a local density of 3.5 ± 2.0% of the thin disk, exponential scale height, hz, of 860±200 pc and exponential scale length, hR, of

Type
Research Article
Copyright
Copyright © Astronomical Society of the Pacific 2001