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Local Surface Density of the Galactic Disk from a 3-D Stellar Velocity Sample

V. I. Korchagin·T. M. Girard·T. V. Borkova·D. I. Dinescu·W. F. van Altena
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Abstract

We have re-estimated the surface density of the Galactic disk in the solar neighborhood within $\pm$ 0.4 kpc of the Sun using parallaxes and proper motions of a kinematically and spatially unbiased sample of 1476 old bright red giant stars from the Hipparcos catalog with measured radial velocities from Barbier-Brossat & Figon (2000). We determine the vertical distribution of the red giants as well as the vertical velocity dispersion of the sample, (14.4 $\pm$ 0.26 km/sec), and combine these to derive the surface density of gravitating matter in the Galactic disk as a function of the galactic coordinate $z$. The surface density of the disk increases from 10.5 $\pm$ 0.5 $M_{\odot}$ / pc$^2$ within $\pm$ 50 pc to 42 $\pm$ 6 $M_{\odot}$ / pc$^2$ within $\pm$ 350 pc. The estimated volume density of the galactic disk within $\pm$ 50 pc is about 0.1 $M_{\odot}$ / pc$^3$ which is close to the volume density estimates of the observed baryonic matter in the solar neighborhood.

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V. I. Korchagin, T. M. Girard, T. V. Borkova, D. I. Dinescu, W. F. van Altena. 2003-08-15. Local Surface Density of the Galactic Disk from a 3-D Stellar Velocity Sample. https://doi.org/10.1086/379138

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