Using a complete sample of about 330,000 dwarf stars, well measured by Gaia DR3, limited to the galactic north and south solid angles (Formula presented.) and up to a vertical distance of 2 kpc, we analyze the vertical structure of the Milky Way stellar disks, based on projected tangential velocities. From selected subsamples dominated by their corresponding population, we obtain the thin and thick disk scale heights as (Formula presented.) pc and (Formula presented.) pc, respectively. Then from the simultaneous fitting of the sum of two populations over the whole sample, assuming these scale heights, we estimate the thick-to-thin disk number density ratio at the galactic plane to be (Formula presented.), which is consistent with a previous result by the authors: in the galactic plane there is a significant number of thick disk stars, possibly as many as thin disk ones, which also points to the existence of more thick disk stars than generally thought. The overall fit does not closely follow the data for (Formula presented.) pc and points to the presence of more stars beyond the thin disk that cannot be accounted for by the two-disk model.

Vertical Structure of the Milky Way Disk with Gaia DR3

Carraro G.;
2023

Abstract

Using a complete sample of about 330,000 dwarf stars, well measured by Gaia DR3, limited to the galactic north and south solid angles (Formula presented.) and up to a vertical distance of 2 kpc, we analyze the vertical structure of the Milky Way stellar disks, based on projected tangential velocities. From selected subsamples dominated by their corresponding population, we obtain the thin and thick disk scale heights as (Formula presented.) pc and (Formula presented.) pc, respectively. Then from the simultaneous fitting of the sum of two populations over the whole sample, assuming these scale heights, we estimate the thick-to-thin disk number density ratio at the galactic plane to be (Formula presented.), which is consistent with a previous result by the authors: in the galactic plane there is a significant number of thick disk stars, possibly as many as thin disk ones, which also points to the existence of more thick disk stars than generally thought. The overall fit does not closely follow the data for (Formula presented.) pc and points to the presence of more stars beyond the thin disk that cannot be accounted for by the two-disk model.
2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3492760
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