Kinematical and Ellipsoidal Properties of the Inner-Halo Hot Subdwarfs Observed in Gaia DR3 and LAMOST DR7

TL;DR

This study analyzes the kinematic and ellipsoidal properties of inner-halo hot subdwarfs within 15 kpc using Gaia DR3 and LAMOST DR7 data, revealing their velocities, angular momentum, and Galactic motion characteristics.

Contribution

It provides the first detailed kinematic analysis of inner-halo hot subdwarfs, including their velocities, angular momentum, and Oort's constant, based on Gaia and LAMOST data.

Findings

Calculated spatial velocities for inner-halo hot subdwarfs.

Determined the Solar motion and vertex longitudes.

Estimated the average Oort's constant for the sample.

Abstract

Here, we report the kinematical parameters of inner-halo hot subdwarfs located within (d lower than or equal 15 kpc) at high Galactic latitudes (b^o greater than or equal 20). The study included three program stars for one of the extreme He-rich groups (eHe-1) with eccentricity (e=0.65) and the z-component of the angular momentum (J_z=4288.66 kpc km s-1), the inner halo program I with 121 points (T_eff greater than or equal 24,000) and their subsections, i.e. inner halo program II (sdB; 79 points) with (40,000 greater than or equal T_eff greater than or equal 24,000) and inner halo program III (sdO; 42 points) with (80,000 greater than or equal T_eff greater than or equal 40,000). First, we calculated the spatial velocities (U_avg, V_avg, W_avg; km s-1) along the Galactic coordinates and subsequently their subsections sdB and sdO. Second, we calculated the vertex longitudes (l_2) and the Solar motion (S_sun=41.24 +/- 6.42 km s-1) as well as their subsections. Finally, based on the kinematic relation of the ratio (s_2/s_1) and our previously computed numerical value of the angular rotation rate (|A-B|=26.07 +/- 5.10; km s-1 kpc-1), we obtained the average Oort's constant.