# Kinematics and Velocity Ellipsoid of Halo Red Giants

## TL;DR

This study analyzes the kinematic properties of halo red giants using a large dataset to determine velocity ellipsoids and Oort constants, revealing insights into the Galaxy's rotational dynamics.

## Contribution

It provides new measurements of Oort constants and velocity ellipsoids for halo red giants, based on extensive survey data and subsample analysis.

## Key findings

- Oort constants A = 15.6 ± 1.6 km/s/kpc, B = -13.9 ± 1.8 km/s/kpc
- Galactic rotational velocity approximately 221 km/s
- Velocity ellipsoid parameters for halo red giants

## Abstract

In the present paper, we aim to determine the kinematical properties, velocity ellipsoid, and Oort constants using a sample of halo red giants. The study is based mainly on the space and radial velocities of about 1583 red giant stars collected from the SEGUE-1 and SEGUE-2 surveys. We divided the sample into three subsamples, the inner halo, the outer halo and the stars near the galactic plane. The fitting of the radial velocity equation gives a the mean of Oort constants, A = 15.6 +- 1.6 km s-1 kpc-1 and B= -13.9 +- 1.8 km s-1 kpc-1, the angular velocity |A-B|= 29.5 +- 0.2 km s-1 kpc-1 implying a rotational velocity of 221.25 +- 26.66 km s-1 if we take the distance to the Galactic center as 7.5 kpc.

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Source: https://tomesphere.com/paper/1905.07614