Kinematical and ellipsoidal properties of the inner-halo hot subdwarfs observed in Gaia DR3 and LAMOST DR7

Abstract

Here, we report the kinematical parameters of inner-halo hot subdwarfs located within (d≤15kpc) at high Galactic latitudes (bo≥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 (Jz = 4288.66 kpc km s−1), the inner halo program I with 121 points (Teff≥24,000) and their subsections, i.e. inner halo program II (sdB; 79 points) with (40,000≥Teff≥24,000) and inner halo program III (sdO; 42 points) with (80,000≥Teff≥40,000). First, we calculated the spatial velocities (U¯,V¯,W¯;kms−1) along the Galactic coordinates (i.e., 25.73 ± ± 5.07, 28.79 ± 5.37, −14.51 ± 3.81) and their dispersion velocities (σ1,σ2,σ3;kms−1) = (161.94 ± 12.73, 140.31 ± 11.85, 101.57 ± 10.08) and subsequently their subsections sdB and sdO. Second, we calculated the vertex longitudes (l2) and the Solar motion (S⊙=41.246.42kms−1) as well as their subsections. Finally, based on the kinematic relation of the ratio (σ2/σ1) and our previously computed numerical value of the angular rotation rate (|A−B|=26.07±5.10;kms−1kpc−1), we obtained the average Oort's constants as (A&B;kms−1kpc−1) = (9.38 ± 0.33, −16.69 ± 0.25).